EV Z3

More Exposure

2011-11-28T17:43:00.001-08:00

A few weeks ago I took the car to a couple of different events, and I'm finally getting the opportunity to share it. The optimal word here is "different" as the experiences couldn't have been more different from one another. The first, was a car show.

People who've been following this blog for a while may remember that last year I was invited to bring the car to General Dynamics for their employee car show. It's worth noting that I don't work for General Dynamics, but I know someone that does, so really I'm not qualified to be there. Last year he suggested to the organizers of the event that I come. They were quite happy to have me there and I was available so I went. The car was a big hit, and when I was driving out of the parking lot, they told me they'd like me back next year. I agreed.

Well, mid-October rolled around and they did indeed contact me asking if I would bring the Z3 back for display. So the first week of November, I drove down to their offices ready to answer all the questions I knew were coming. Apparently I didn't warrant being placed with the "Premium cars" like last year. They just lined me up in some random spot on the grid. If they'd had some foresight, they would have put me next to the Nissan Leaf that showed up, but they didn't.

It turns out, it really didn't matter where I was lined up. Eventually, just like last time, there was a crowd around the car. It's really the perfect venue to show the car. This is a company full of technically oriented people, many of them engineers. Each was curious to see the project and how it was done. Several stepped forward to ask questions, many of them quite good, all picking my brain for details. There was one guy who was telling me about the car he has and the conversion he's had planned for it for some time. Hopefully, getting the chance to see a conversion first hand will inspire him to move the process along.

This was the first chance I've had to show the car with all the new safety systems in place. Of course by safety systems I mean sheets of Lexan strapped to the top of the batteries. Still, like I'd said before, you could throw a bucket of wrenches in the engine compartment and there's no way for them to short on anything. But best of all, there's no way for anyone to get their fingers on anything that could harm them. They might cut them selves on something if they stick their hand somewhere too tight, but certainly no chance to electrocution. It was very satisfying knowing that no one could hurt themselves by mistakenly touching something they shouldn't.

All in all it was a very successful event. I believe several people walked away with a more positive view of EVs.

The next day I was at an event sponsored by a local group called Gang Plank. This was set up by another local EV enthusiast who also attended EVCCON in September, Kevin Larsen. Gang Plank is what I would describe as a co-op for business start ups. They have work space and meeting spaces available to people who are interested in starting a business but don't have office space available to them. Once a week they have a brown bag session for a topic the administrators there think might interest their clients. Kevin worked with them to arrange a brown bag session concerned with converting a car to an EV. Understandably, Kevin thought it might be a good idea if I came along and gave a short presentation, show the car and answer some questions.

I thought our presentation was informative if not particularly polished. What surprised me was how supremely uninterested the group seemed to be. There were perhaps 6 people (out of 35 or so) who bothered to gather in front of the dais we used and most seemed only casually engaged in what we were saying; occasionally someone would look up. Apparently to see if we were still there. When the question and answer session came up, there were a few good ones, but I found myself answering questions more about EVs in a broader sense rather than the merits or particulars of converting a car. For instance someone asked me about the true carbon off set of an EV versus a gasoline powered car. I did my best to answer these questions, but I'm no authority on such matters. But more than anything the questions betrayed the fact that what we were presenting to them was really a few steps ahead of where they were as a group. Just the wrong audience for our material.

After the presentation, a few people and I wandered back to where the Z3 was so that they could look it over. It seemed more like something to pass their time rather than something that really interested them. The whole time I found myself hoping that the entire endeavor wasn't simply a waste of time. Everyone was very nice but no one seemed particularly interested. There was an owner of a Leaf there who was quite engaged, and we chatted for a while, but he's one of the initiated (so to speak). The whole day stood in such stark contrast to the events at the car show the day before. I took solace in the fact that if nothing else these people saw a REAL EV that's being used on a daily basis by a REAL person. Hopefully that will stick with them.

It's An Imperfect World, Screws Fall Out

2011-11-04T09:06:00.000-07:00

One of the frustrating things that occurred during this summer's work on the car was that stuff seems to have broken all on it's own. Through no intervention on my part, at least two items on the car stopped working. Trust me when I tell you I've been responsible for breaking a number of things related to the car, but I think I'm innocent here.

After I hooked the batteries back up and turned on the new TBS Link-Pro meter, I had to run through a series of menus to set it up properly. When it came to the prescaler menu, I selected the 1/10 prescaler because that's what I was using for the older Xantrex Link-10. To my surprise the meter read that my pack voltage was 68.9 volts. Well that's a bit off as my pack voltage is 160V. I double checked the meter looking through all the settings and found everything was correct. Eventually I pulled the meter out and measured the leads coming from the prescaler itself only to find that the leads which should have read 16V, instead read 6.89V. Well that put the blame solidly on the prescaler, the meter itself is fine.

I checked and the prescaler was hooked up correctly, after all I hadn't changed any of that. But there was no doubt about it, the prescaler was spitting out the wrong voltage. I have no idea why it broke, how it broke or when it broke. All I know is that when I unhooked the batteries in May, it worked, and when I put them back together in September it didn't.

Not being an expert in electronic circuits, I have no idea how to fix the prescaler. As far as I'm concerned, I put 160V on two wires that lead to a little box in which some magic happens, and then on the two wires coming out the other side, there's 16V. Besides, the unit is sealed. I was left with one option and that is to replace it.

I got the replacement 1/10 prescaler and thought I'd measure it before I disassembled the dashboard to put it in. I carefully hooked it up to the positive and negative leads to the 160V system, and to my amazement the other end read 48.3V. What the hell!? Now I had two different prescalers, each of which should be working fine, but both spit out completely different and incorrect voltages. I sent the new one back at which point they evaluated it and said it was fine. What!?

I'd ordered the part from Evolve Electrics and was working with Justin Dunn. It turned out that both of us learned something about this prescaler and the TBS meters. Both the 1/5 and the 1/10 prescalers will read 48V when hooked up to the pack. It's only after you hook it to the meter does it somehow adjust the voltage and display it properly. Like I said before, magic. Neither of us expected that. By the way, Justin was great to work with. I feel quite comfortable recommending Evolve Electrics.

The second thing that seems to have broken while the car was sitting still was the tachometer. I drove the car around for a couple days after putting it back on the road, and all was well. But one evening I left my destination to head home, turned on the lights and found that the tachometer's dial didn't light up. A few moments later I realized it wasn't working at all! It had been working when I arrived earlier when the lights weren't on. When I came to a stop light, I turned off the lights and revved the motor. Sure enough the tach sprang to life and worked perfectly. It was hovering at about 2000 RPM and I turned the lights back on and the needle froze where it was.

I have no idea what would cause such strange behavior, but I do know that I didn't touch any of those systems or their wires when I was performing the work this summer. But then it just got worse. A couple weeks ago I was accelerating from a light in second gear. At about 35 MPH I went to shift to fourth and I noticed that the tach read 5000 RPM. I thought that was odd because 35 MPH in second gear is about 4000 RPM. I dropped it into fourth and watched the needle come down to about 3000 RPM, which I know is too high for that speed. Suddenly the needle jerked up to 5000 RPM, then 6500 RPM. By the time I finished my trip, the tach's needle had moved well beyond the 8000 RPM top of the dial, and was approaching a full lap coming around to 0 again. Now the tach just jumps around all over the place providing no useful data. It's just become a distraction. I believe I'll be unhooking it.

So what the heck happened to these two pieces of equipment while they were sitting still and not being powered over the summer? I really wish I knew. The tach I can live without. I'll probably replace it at some point, but for now, it stays. Justin sent the prescaler back to me and I popped it in yesterday. It works just fine and the meter is behaving like I expected. If you ever end up with the TBS meter and prescaler combo, don't bother taking a voltage measurement from the prescaler itself, it won't be what you expect it should be. It has to be hooked up to the meter.

Safety Issues

2011-10-31T10:07:00.000-07:00

While at EVCCON, I spent a good deal of time looking at and admiring all the conversion, and trying to get ideas for how I might improve the Z3. Among the things that made an impression on me was the fact that the constructors of virtually all the EVs had made a great deal of effort to make the car's motor bays "touch safe." The Illuminati team mentioned that during the X-Prize contest, they were required to shows that all the compartments that held batteries and electronics were also "wrench safe." Meaning that you could throw a wrench into any compartment or area in the car and there was no danger of a short or explosion.

It became clear to me that I'd fallen short in this area. I never really considered putting much effort into making the z3 "touch safe" or "wrench safe" figuring I was the only one in that area, and I know what's safe and what isn't so why does it matter? But as I watched all these people milling around my car, I found myself with an unusually high level of anxiety worrying about someone hurting them self. Several times people leaned over the motor and battery compartment to get a close look at something, only to have their EVCCON lanyard drag across the top of the cells. In fact a local boy came in to look at the neat cars. I explained to him not to touch anything for safety reasons, but then watched him like a hawk to be sure he was safe.

I realized at that time that not only would making the whole motor compartment touch safe be a good idea, it was essential. Here's the thing... I never anticipated that the car would draw as much attention as it does. I never envisioned that I'd be taking it to car shows and there would be strange people so interested in it and getting so close to it to inspect it. Imagine what the news media (especially Fox News) would say if some hapless person were accidentally injured, or worse, by an electric car at some car show. In one fell swoop, I'd be responsible for not only injuring or perhaps killing some poor soul, but the EV movement as well!

At the public car show the last day of the conference, one of the attendees, David Hrivnak, made a point of pulling me aside and asking me what I intended to do about the safety issues. Not "are you thinking about doing something?", but "what are you going to do?" David clearly recognized the risks I was exposed to and the implications, and had the courage to bring it to me. By that time I had already got it. I was absolutely on the same page as David. I understood what was at stake and the imperative to resolve the safety concerns he, and by that time, I had. Thanks again David, I'm very grateful.

I had been looking at the other cars to see which ideas of theirs I could steal. What I saw was basically two ways of covering the batteries, terminal and high voltage connections, if they were in an area where they were exposed. Either they were sealed in a custom built box, or they were simply covered with plastic. For anyone who's seen the Z3 or the pictures of it, you know there is no room to redo things in order to incorporate battery boxes. That meant I was going to need to figure out how to simply cover the terminals of the batteries. In addition, I needed to figure out how to cover the electrics bay where the controller and contactor are. That bay is the only placed where the positive terminal is exposed that has full pack voltage.

After a little research I learned that the best material was probably Lexan, so I purchased some from the local hardware store and started measuring and cutting. Cutting Lexan is not too difficult. There are special blades available to cut it, or you can cut it with a thin blade, fine toothed saw. When you cut it with a blade, you simply score the same line 15 or 20 times and then bend the plastic to kind of tear it through the rest of the way.

I knew the front batteries were going to be the most difficult to cover. It looks easy enough, but the clearance between the front corner of the batteries and the hood is as little as 1/2". So to place a piece of Lexan on top of the terminals and run it straight to the edge of the batteries would certainly be hit by the hood once it was shut. It would require careful cutting and measuring to make it fit. Since you can't actually see the space once the hood is closed, I used Play Dough to figure out the clearances. I simply shaped a chunk of it to the size I needed and laid it on the area where I thought the battery cover and the hood touch. Then I shut and opened the hood and inspected the Play Dough. You can easily see where it's been crushed too thin, or even pierced. That's where I needed to trim and do some more fitting.

Ultimately I found I needed to bend the front edges of the cover to clear the hood. I found a piece of scrap Lexan, and sicked my heat gun on it. I used the low setting thinking that I didn't want to heat it too fast and potentially over melt or set the piece on fire. It worked pretty well but I found that when I tried to bend a longer edge, the plastic started to show bubbles inside by the time it finally started to wilt. I tried the higher temperature and that turned out to work much better. First, it was faster, but second since the plastic was exposed to the heat for a much shorter period of time, so there was no time for those bubbles to appear. So, higher heat yielded a much cleaner looking bend.

In the detail shot you can see what I mean about the plastic bubbling under the heat gun. Structurally, it seems fine, but cosmetically it's kind of ugly. You can also see the slots that I cut into the plastic and the clips I'm using to hold the piece in place. These clips are an assembly of two channel clips used to hold a mirror up to a wall. This works fine, but admittedly it's ugly. I'd love to have come up with a better way to hold this cover down, but this was the best thing I could think of. I also drilled little 3/32" holes in the Lexan next to each of the positive terminals. This way I can stick the probe of my multi-meter through the plastic to measure any one or group of batteries I want.

On the larger set of batteries I used D-hooks mounted to the aluminum frame and Velcro straps to hold the piece down in place. Again, not the best looking solution. You can see that the plastic follows the curve of the batteries nicely. In the detail shot, you can see that I was able to shape the plastic to accommodate the 2/0 cable coming off the pack, and turn the corner down just a bit to make it less lethal. I used high heat to make these bends; notice the difference in the plastic from the first bends I made. It looks much better.

The cover over the electrics bay took a lot more fiddling and cutting to get it just right. It rests nicely in the grove just below the cushy part of the rubber that seals the area from the elements when the hood is closed. I made a template out of cardboard and then trimmed the plastic to shape. As it happened, I'd run out of Lexan and the only sheets at the store were either too small or way too big (and expensive). So I used an acrylic sheet instead. I can see why people said that Lexan is better. Acrylic is much more prone to snapping, cracking and chipping. I was able to get it done, but it would have been way easier with Lexan.

There is still one more safety concern I need to address, and that's an emergency cut off switch. You may remember that I had the big red slap switch under the hood, but there were two problems with that. One, I had no way of actually slapping it in the event of an emergency, that is if I were in the car driving it, and two, it melted. At some point, enough current went through it that one of the internal contact points melted. You can see pictures of that from a couple posts ago if you wish. To replace it, I got this unit:

This needs to be mounted either in the cabin so that the driver can reach it while moving, or I need to rig up some way of actuating it from in the cabin. I'm thinking that a push/pull cable mounted to the handle should work well. The questions remaining are, where do I mount the switch and where and how do I mount the cable? As of now, I have no idea about either.

EVCCON 2011

2011-09-28T09:12:00.000-07:00

I've finally arrived back in Arizona after having attended the first EVCCON (EV Conversion Conference) in Missouri. I rented a car hauler from U-Haul, borrowed my sister's truck, loaded up the Z3 and then my father and I towed the car 1500 miles to Cape Girardeau. For those of you unfamiliar with the convention, it was put on by the EVTV crew, Jack Rickard and Brian Noto. The idea was to have the people that have adopted the use of, or are interested in EVs with LiFePo4 batteries, come together.

To be honest, I simply had no idea what to expect. My biggest hope was that there would be time to meet with the other attendees and exchange ideas and then see some of the cars up close. The schedule that was printed up was pretty full and I was concerned there wouldn't be much of a chance for that. The convention was scheduled to officially start around 10:00 AM Wednesday. As it turned out, quite a people showed up on Tuesday and began descending on the EVTV shop. We arrived at the hotel Tuesday around 4:00 PM and immediately ran into Mark Emon, one of the finalists for the EVTV $20,000 EV component give away contest. Mark was getting ready to run down to the shop and said that we should come along and drop the car off. We decided we'd follow along and do just that.

When we arrived, there were already 30 or so people gathered around looking at the E-Cobra that Jack and Brian have been working on. Everyone encouraged me to unload the Z3 and then proceeded help. I pulled the truck into the shop (a tight fit) and used one of the ramps inside to facilitate getting it off the trailer nice, quick and painless. Once it was off the trailer, I opened it up so everyone could have a look. There were certainly lots of favorable comments and questions, and it was fun answering them all. Jack explained to me that people started showing up well before the appointed time (some as early as Monday morning) and took over his shop. Though that clearly wasn't the plan, I think he was quite happy to have everyone there. Around dinner time, someone showed up with several pizza's and we all sat around talking about EVs and sharing pizza and beer. I don't know that it gets much better than that. Before I left I asked Jack where he wanted me to put my car and he told me to just park it next to a couple of the others.

The Z3 has never been in better company, nor so thoroughly out classed.

Wednesday we arrived at the shop around 10:00 AM and found that it was already teaming with activity. The previous day, they'd put the final pieces together in the E-Cobra and tried to drive it, but found it would not move under it's own power. Motor spun, but in spite of the fact that the clutch was firmly engaged the car wouldn't move. Six to eight guys were working on it and pulling the transmission to see if they could determine the problem with the clutch. As the day went on, more and more cars arrived, each impressive and a joy to look over. Sebastian Bourgeois' 911, Fred Behning's 1960 Austin Healey Sprite, Charlie and Tamera Rickman's 1973 Opel GT and Daniel Yohannes' Porsche Cayenne just to name a few.

Fred Behning's Austin Healey Bugeye Sprite. One of my favorites.

The back end of Sebastian Bourgeois' 911. Yes, there are two motors in that space, one on top of the other.

Eric Kriss' 356 Porsche replica. An astonishingly beautiful build.

A peek into the back end of Duane Ball's Porsche 904 replica. Another gorgeous conversion.

I can't express what a joy it was to talk to each and everyone of these great people. Instead of the first two questions out of everyone's mouth being "How far will it go?" and "How long to charge it?", they were asking great questions like "How did you solve this problem?" or "Why did you choose that design?" Starting off with a pool of people that already "get it" set the stage for some very substantial, entertaining and valuable conversations. This was truly a fantastic day.

The next two days took place at Jack's hanger out at the Cape Girardeau airport and were comprised mostly of various speakers and eating (man, there was a lot of food). The speakers lined up ranged from individuals that own and run conversion shops, suppliers of EV components (both sellers and manufacturers), industry analysts, with a couple of speakers on technical issues thrown in for good measure. I had no expectations for most of the speakers and very high expectations for others. As it turned out, each speaker was quite good. A few stood out, having put together truly informative and interesting talks, but also delivering them quite well. George Hamstra from Netgain motors gave two talks, both packed with information about where we, as a global community, are going in regards to oil usage. Eric Kriss delivered a terrific analysis of why EVs make sense now and why and how that's come to pass. Ryan Bohm of EVSource delivered a great talk about a variety of topics related to EVs including details of the new WarP-Drive controllers and safety concerns regarding EVs. The latter made a big impression on everyone. It was well stated and impassioned.

Thursday evening, Chris Paine, director of "Who Killed the Electric Car" and "Revenge of the Electric Car" gave a talk. It was an interesting talk, but largely about the concerns and issues surrounding making movies. He is, however, clearly passionate about EVs. After speaking for an hour or so, and madly texting and emailing his producer to get permission to show us "Revenge of the Electric Car" he had still not received the OK. Ultimately he took the decision into his own hands and rolled the film. It's set to come out October/November in different cities, so it was a great opportunity to see it early.

The film was basically an overview of four different groups, or in one case a person, working to bring an EV to the market. It featured, Bob Lutz and his efforts at shepherding the Volt into production at Chevy, Elon Musk and Tesla's saga, Carlos Ghosn and Nissan's preemptive dive into the EV world, and finally Rev. Gadget and his attempts to put together a 120 mile range Porsche 356 replica conversion that he can market. It was basically a documentary on the difficulties, setbacks and successes of each. It was well worth seeing and very entertaining. When it comes to your city, I think it's worth your time.

Later in the day on Friday, we all went out to the runways behind the hanger for some festivities with the cars, including weighing each, a drag race, and an auto cross set up by the local SCCA. The Z3 came in at 3285 lbs, which is rather portly compared to several others, being that so many of the cars there were built from light weight sports cars, or replicas. (A side note, and I don't remember the source, but the stock Z3 actually weighed more than a standard 2 door E36, BMW 3 series chassis.) What I thought was odd was the weight was dead on identical to when I had it weighed after it hit the road a year and a half ago, but the weight distribution went from 52% / 48% front to rear weight bias, to 50% / 50%. Can't explain that.

I've never participated in any sort of drag race. Not the official sort on a track, or the race off the line at the local street light. It's just not my thing. But I have to admit, it was great to find out just how well the Z3 would perform in an official, measured way. As it turned out, my car was the first weighed and the first at the line to run the 1/4 mile. It took some time for the next car to get weighed and staged. When we were all set, the lights on the tree (that's drag racing talk for a pole with lights on it) gave us the green to go. I started in 2nd gear and screeched the tires like mad, much to the crowd's approval, but I knew that meant I'd lost time. At the end of the run, I left it in 4th, which meant my torque was dying off, and I lifted just before the end. Like I said, I've never done this. But I realized right away I could do better. So the first run was 19.2 seconds at 61.8 MPH.

I lined up to try again. This time I started in 3rd and hit the power with a bit more care to be sure not to spin the tires. When 4th was losing torque I went to 5th, and I could feel a bit more torque kick in. That run was better at 18.9 seconds, 66.4 MPH. All in all, in a field of 22 cars, the Z3 came in a respectable 9th. Aside from Ron Adamowicz's purpose built Camaro drag racer (which was awesome) the top runner was Dave Hrivnak's Tesla Roadster that ran it in 13.1 at 88.2 MPH. Later, Dave gave me a ride in the Tesla, for which I will remain eternally grateful. He took me down the 1/4 mile run. I don't think I've ever experienced anything so blisteringly fast. I'm not even sure the magnetically launched roller coasters I've ridden accelerate that fast. It was simply astonishing.

Having run what I thought was likely the best 1/4 mile I could, I went over to the auto cross. I picked out a helmet and was given an instructor. He explained to me how to read the course and how to attack various corners. We set off on the first lap and I did fairly well finishing in the mid 50 second range. But the instructor said "This car has a lot more to give, so I know you can do better." I knew he was right since I hadn't caused the tires to squeal once. Within a couple more laps I was down in the upper 40's. I ran several more times trimming off a little more each time. The car performed great! I was throwing it into corners and driving it like it was meant to be driven. The last big corner you hit at pretty good speed and I was nearly drifting around it, the back end just barely hanging on. When it was all said and done, it got down to 44.7 seconds. Not the best time, but in the top of the pack. It would likely come as no surprise, but the Tesla set the best time in the mid 41's.

Ultimately I had to stop because I was running low on charge. That was the most fun I've ever had in a car, and that includes a few memorable nights in high school and college ;)

Saturday, we wrapped up at the hanger and then all of the cars drove down to a park in the middle of town for an EV car show. Each of the cars was on display and each builder was available to answer all the normal questions posed by people just seeing EVs for the first time. It was a great crowd and there were a number of people from the media there to film and photograph the cars as well as interview the drivers. We left the park in a police escorted parade around Cape Girardeau. Here is a fantastic video put together by one of the participants. He highlights each car and puts some information up about each (though he did get a few facts wrong on mine, it has an 11 inch motor!).

At the end of the parade, all the cars were gathered in the parking lot of the hotel, parked and arranged ever so carefully for some photos. First the cars by themselves, and then all the owners went and stood by the cars. Sadly, I did not have may camera. I'm hoping that one of the kind people that has a copy will send one to me.

It's difficult to put into words, but that was a profound and powerful moment. I think everyone felt it and knew it was important. There was something palpable in the air. The sense that this was the beginning, the beginning of something big. Sure manufacturers are going to begin producing EVs for the public. But I, and I think everyone there feels that a big part of the future of EVs will be conversions. We were there to bare witness to the beginning of a movement that will change the world.

Cool Air

2011-09-14T19:48:00.000-07:00

I took the Z3 down to the shop today to have the A/C lines evacuated and charged. I had to explain to the technician that was going to drive the car into the service bay how to operate the car. I wanted to make sure he was comfortable. There really is no trick to starting and driving it, but the lack of noise can throw people off.

After an hour and a half or so, the service rep came out to ask me if the oil that ships in the compressor has any dye in it. "Why, are you seeing dye?" They weren't, but he explained that the system was not holding a vacuum and they couldn't pin point the location of the leak. So they were thinking of putting some refrigerant in system to see if they could see the leak when it spit out colored stuff. The thing is, it's the oil in the systems they use that contain the dye when they want to track a leak, but we can't contaminate the MasterFlux system with standard oil for A/C units because it uses a special type of oil.

I asked them to do what they could to find the leak and moped back to my seat dreading having to take the system apart again. About 45 minutes later, the tech that drove the car into the service bay came back and asked me how much refrigerant they should put in the system. He explained that they'd put just under 2 lbs. in and it wasn't quite as cold as they like to see. Uh, what? I thought it wasn't sealing properly? He explained that it didn't under vacuum, but once they put refrigerant in the system, it seemed to be holding pressure just fine.

No one seemed to really know why this would be the case, or how something like this might happen. But the service rep hazarded a guess. He was thinking that the seals in the system may simply have been allowing air into the system when they were drawing the vacuum down because they'd dried out from the system being empty for so long, but once they turned the compressor on and the oil started flowing around the innards of the system, it may have lubricated the O-rings and helped them seat. Since no one had a better idea than that, we decided that must be it.

They put a thermometer in the vent and let the system run for several minutes to get a temperature reading of the out put. It read 60 °F. That is on the high end of normal. He noted that the high pressure side of the system had lower pressure than they're used to seeing. While I don't know this to be the case, my suspicion is that this system, which is designed to run between 120 and 420 VDC is operating at the low end of the scale in my car at only 160 V. So my guess is that it simply doesn't have the voltage behind it to drive it hard enough to get higher pressures.

In any event, the drive home was very pleasant. The compressor is pretty quiet. Standing over it while it's running, you hear a tick-tick-tick-tick sound, but its not particularly harsh or disturbing. Inside the car, I can feel it more than I can hear it. Well I can't really hear it from in the car, but I can feel it in my feet. Without it being mounted on those rubber bushings, I'm sure it would be very shaky indeed. All in all, I'm pleased. I would have liked another 10 °F temperature drop, but this is so much better than no A/C, I'm not complaining. I will be keeping an eye on it over the next few days, weeks, months to see if the output changes. I'm not convinced there's no leak just yet.

I also had them align the front end so that it has 0° toe-in. Normally cars are aligned with a slight 1 to 2° toe-in for tracking purposes. Without that, cars will tend to wander about the road, potentially following cracks or grooves in the pavement. Not a desirable trait really, but neither is an EV that uses more energy that in needs by scrubbing it off with the tires. As it turns out, they didn't have to adjust it much, and like I said yesterday, I really don't know if it's had an impact yet. On that note, I did receive the new 1/10 pre-scalar today, which will allow me to measure energy in and out again. Now I get to begin the long, arduous task of disassembling the passenger side dashboard.

On the Road Again

2011-09-13T20:57:00.000-07:00

All Willie Nelson references aside, the Z3 is back on the road. There's a lot to tell, and I'm sorry I haven't posted more as I was working, but as most of you know, I have a deadline that I had to make. This made for some very long days and nights in the garage. I'll touch on some of the highlights, good and bad.

The controller for the MasterFlux compressor comes as a circuit board with an aluminum heat sink anchored to one side and all the components open to the world on the other side. You don't have to be a computer expert to know that probably ought to be protected from the elements. I started looking for a project box big enough to put it in and would fit in the space I had picked out for it, but found none. It wasn't long before I realized I was going to have to build my own. Well, I figured that would be fun. My material of choice would be thin sheets of aluminum, but I don't have a press break, or access to one. There was no way I was going to be able to build a nice box out of metal with neat edges.

OK, that meant plastic was the material of choice. I found someone on eBay selling sheets of PVC plastic, so I ordered a 2'x4' sheet. I was able to cut it quite easily with a utility knife and a metal straight edge. It was clearly formed with a PVC foam-like material rather than the type used to cast PVC joints for plumbing. But on thing was certain, it would glue the same. I very carefully cut sheets the proper size, planning on two sheets per side, sandwiched together, with staggered edges so I would have more surface area to make sturdier lap joints at the corners.

My plan to build a box around the controller was going well. But then my dad had a great suggestion. He noticed that the heat sink is a bit larger with the edges sticking out beyond the edges of the circuit board, so he suggested making that one side of the box and simply enclose the circuit board. Brilliant! I was able to do just that and build a secure mounting system and put it exactly where I had hoped I would be able to. This had the added benefit of leaving the heat sink open to the outside air for cooling

Notice the fins of the heat sink facing the front of the car between the two battery packs. Right next to that, to the left, is a little project box that holds a large diode and two relays. The diode is to prevent current from the capacitors on the controller board from flowing back into the car's traction system should the voltage in traction system drop below the voltage stored in those capacitors. Apparently this was a common problem with the MasterFlux units that they've decided to overcome by recommending you buy an extra $25 part. The relays work like this: the on/off switch on the car's dashboard for the A/C system triggers one relay, which provides power to the fan mounted on the condenser at the front of the car, and to the second relay. That second relay simply makes a contact that will allow the 5V signal back to the controller turning it on.

(By the way, notice the nice new braided connectors between the batteries. Nice huh? )

All of this should work flawlessly. In theory. You see, I tested what I could before hooking everything up, but there was no way to test all of it as one system after it was hooked up, until all the batteries were in. Plus, I have no idea if it's even safe to run the compressor before the system has been evacuated of air and charged. In fact, I've been trying to reach Revolt Electric (the resellers of MasterFlux products) to ask them about this and a few other things but they have been, how shall I say, less than diligent about returning emails or phone calls. Part of being a reseller is living up to the responsibility of offering end user support, and they're falling short at the moment.

Tomorrow morning, I'm taking the car into a local BMW shop to have them evacuate the system and charge it. First, they'll put a vacuum on the hoses and pump all the air out. They'll leave it like that for a couple hours to be sure it holds the vacuum. If it does it's good to charge. At this point I have no idea if it will. I can't express how much I hope it does, but there's no telling. Since one of the new joints in the system had a brazed fitting, I think that one will be fine. The other one was still an accursed compression fitting. I give it a 50% chance of holding a vacuum.

If it holds up they'll charge it and I get to turn it on for the first time. I'm not worried about incorrect wiring and/or damage to the system, but there is the distinct possibility that it simply won't work for some reason which I can't conceive of at the moment. I'm about 90% sure that will go well. Whether I drive out of the shop with A/C tomorrow, only time will tell.

They are also going to align the front end to take out all the toe-in. I never had it re-aligned, so it will be interesting to see how much of an impact this has on energy consumption. Sadly I won't know right away because the new meter I put in isn't working.

Actually, the meter is not the problem, it's the original pre-scalar I was using with the Link-10 meter. When I put power to the system yesterday, I turned on the meter and started running through the various menu setting to set it up for the car. When it was done, it read that the system voltage was 68.8V. Wha... I double checked that I'd selected the 1/10 pre-scalar knowing full well that I'd never seen a 1/4.3 setting that would be necessary to see 68.8 Volts. Eventually I pulled the meter out of the console and actually measured the voltage on the wires coming from the pre-scalar. I found that it read 6.88 volts. Well how about that. Apparently while the car sat doing nothing over the past 4 months, the pre-scalar developed some sort of problem that renders it useless. I have no idea how, or why, but a replacement unit is $54. *Sigh* A new one is on the way.

Astute readers will have noticed in the picture of the motor bay that the big red slap switch I had in the prior builds is gone. "Where did it go" you ask? Well after I pulled it out to start the work in the area, I noticed something peculiar about one of the contacts on the positive terminal side. Take a look:

You can see in the top right side what the contact pads should look like. They are little silver pads soldered on the copper bar. However in the bottom frames, you can see that one of them has completely melted away. The bottom left picture is the bottom bar in the contact, and the bottom right picture is it's mate above. At some point, there was some serious arcing in there that, for all intents and purposes, destroyed this switch. Well there was no way I was going to put it back like that, and I see no reason in replacing it with a like one as there will now be the possibility of sending even more current through it. Nope, I need to find some other safety disconnect. But, that will have to wait for later.

I finally added an expansion tank for the coolant used to keep the Zilla cool. Finding a location for it was a challenge. The fact is, it's on the opposite side of the car from where the pump is. As a result, there are coolant hoses running all over the place. The underside of the car is, quite frankly, a bit embarrassing now. It's just too crowded with stuff and it all looks a bit thrown together. Such is life. The cooling system does seem to work great though.

Yesterday after putting everything back in and together, I was working near one of the batteries while touching the chassis of the car, and I grazed a battery and felt an unmistakable shock. What the! My mind raced. I got out my meter to check and sure enough, there was continuity between the chassis and the battery pack. I stood there cursing, wondering how the hell that had happened. I disconnected the positive most terminal and started looking to see what had happened. Eventually I isolated the problem to the motor. My first though was that as I'd lowered the battery pack on top of the motor, I must have crushed one of the lugs and it shorted out to the motor's housing.

There was no way around it, that pack was going to have to come out. Mind you, this is coming less than an hour after I'd put the final bolt in holding everything together. What a bitter pill that was. Rather than take the pack out as a whole, I decided the best thing would be to dis-assemble the first row of batteries and remove them so that I could see the terminals which are under them and if I'd crushed a lug.

What I found was no crushed lugs, but one was clearly wedged in there and under pressure. I as able to get to it and get it out. I found that the plastic boot on the terminal had what amounts to a pressure wound on top of it and was actually pierced, ever so slightly. The heat shrink tube underneath it looked intact, but I cut if off and could clearly see a hole you could fit a pencil lead through when I held it up to the light. There it was, that was what had been touching the chassis. I found a less risky path for that wire and bolted all the wires back in place. I checked and there was no continuity. Problem fixed. Whew!

This morning, I re-assembled the rest of the system, put power to the system, dropped the car to the ground and carefully drove out of the garage. I took off down the road cautiously and found that the car was driving perfectly. Furthermore, the wobble that was in the drive line before it went up on blocks was now completely gone. The Warp 11 motor was perfect again. Finally, on the road again.

Tomorrow is my appointment with the shop, which I'll report on. The rest of the week will be spent replacing that pre-scalar, and getting ready to trailer the car and tow it to Missouri for EVCCON. I am genuinely looking forward to that.

The A/C Lines Are Installed

2011-08-30T17:37:00.000-07:00

I confess, I expected that getting the A/C lines made to hook up to this compressor was going to be a challenge. You could even say I was pessimistic about the whole affair. I just couldn't envision how these lines could be made to fit in place, tie seamlessly into the car's existing system and hold pressure. For a while it looked as if my doubts were justified.

When I got the hoses back toward the end of last week, the technician handed them to me and began to explain how I should hook them up. He said I should hook both ends up first, and then tighten the compression fitting in the middle. I felt a wave of panic when he said "compression fitting." You see, I hate compression fittings. Despise them. If there's a hell, it's occupied by the man that invented them and everyone else who is there is forever forced to try and make them work. It's been my experience that compression fittings work absolutely fine, until you try to put anything in the hose they are on under pressure. Then they proceed to leak everywhere, and nothing you do can makes them work.

I hooked up the long, low pressure line that runs from the evaporator to the compressor, and began carefully tightening the compression fittings. For those of you unfamiliar with how to tighten them, you are supposed to tighten them hand tight and then give the nut another 1/2 turn or so. If you under tighten it, it leaks. If you over tighten it, it leaks and you've ruined the ferrule inside and must replace it or the whole thing. With that in mind, I followed the rules: hand tight, but then I did about a 1/4 turn. I did a pressure test and it leaked like mad. OK, 1/4 more of a turn and another pressure test. More leaking. *Sigh* 1/4 more of a turn and it's leaking worse than ever. Undo the whole thing, check for dirt, debris or any other problems. It all seems fine, so try it again.

This went on for 3 hours or so. It began to become difficult working through the tears of anger and frustration. Eventually I had to resign myself to the fact that it simply wasn't going to work. Oddly, the second hose, the high pressure side, seemed to work just fine. Now I say that having not had the system charged. I fully expect that when I take it down to have the shop draw a vacuum on it, and then charge it up, they're going to tell me it leaks from that joint. I sure hope not, but if one of them is going to leak, that's the one that I can deal with. I can reach it and remove it without dis-assembling the car. The low pressure side requires I remove the larger battery rack under the hood to access it.

I took it back to the shop today and explained my problem. One of the guys, who's clearly been in this game for a while, looked at it and said, "Yeah, that will never seal. It needs to be brazed." That was music to my ears. He said give us a few minutes and we'll take care of it. They brazed a nut fitting on the aluminum tube and crimped it's male counter part on the existing hose. I was a little irritated that I'd spent all that time on a fitting that clearly the expert felt was the wrong part for the job. But I was so happy that it now had the right joint, I wasn't about to complain.

I took the parts back home and began hooking them up. It took a couple hours and I got the new dryer/receiver in place, both new hoses, the compressor mounted and the new lines attached to the compressor. It looks terrific, but I have no way of pressure testing it apart from adding coolant to the system, which I'm not going to do until I know it won't leak. Once the rest of the car is assembled, I'll drive it down to a local shop and they'll do all that for me.

I put together another quick (and very rough) video of what was accomplished today. Take a look...

Another component to this is the controls for the A/C system. They consist of an On/Off switch and a potentiometer that acts as the thermostat. MasterFlux sells a little black box that incorporates both of those items, but I can't imagine using that in the car because it's simply hideous. They say it's mostly for testing, and I can believe that. I picked one up in case I needed it, but I don't think I will, so it's going back. Instead, MasterFlux publish the specs on the device complete with part numbers and how to wire it. I found the very same potentiometer online and bought it. The great thing was they also had a variety of knobs to choose from to mount on the potentiometer's shaft, as well as the molex connector needed to plug all the wires into the controller board. For the On/Off switch I'll be using the original A/C On/Off switch that came with the car. Here's how the whole thing came out.

Down low on the center console, just the right of the gear shift is the little silver knob that will be the temperature control for the system. I really could think of no way to incorporate that functionality into the car's original thermostat dial above. You see that dial just moves different baffles to control the direction of air flow, either over the A/C system's evaporator, or over the heating core. There's no way to hook any electrical component up it. At least no way I was willing to try. I think that little knob will do just fine. The On/Off switch is the top button in that two button module directly to the right of the new Link-Pro meter.

Lastly, you may recall that I was having problems keeping the Zilla controller cool in the desert heat. I think part of the problem was the fact that I was using a radiator that was only 4"x8" in size. Well in the video above, you saw that the new radiator is about 3 times that size. Hopefully it will keep things a bit cooler. But it also has a nice big fan to help suck air through it. Well, I didn't see any point to having that fan run all the time. After all, when I'm sitting idle in traffic, there's no heat generated in the Zilla, or when I'm cruising down the road at 40 MPH drawing only 60 amps, the air moving through the radiator is more than adequate to cool the controller.

What I need is some way to monitor the temperature of the controller and turn the fan on when it starts to get too warm. I started looking and found what I think would work. It's a switch that will close a contact when it hits 122 °F. It opens up again at around 115°. That is well below the point the Zilla begins to complain about heat, but high enough that the fan won't run unnecessarily. The switch itself is just a little button style switch that has to be in contact with the item you're monitoring. The place I've noticed seems to get hottest on the Zilla is the top, right in the center. It may get hotter else where, but I don't have access to where ever that might be. So the question became, how do I mount a small dime-sized switch to the top of the Zilla without it moving around or looking too hideous. Here's what I came up with, you be the judge...

That piece of aluminum is pressed and held down tight to the top of the controller. The switch is held down tight to the aluminum strip. I used some thermal paste left over from my last CPU purchase to help heat conduct into the switch. The switch drives the relay you see at the bottom of the screen, which will then turn the fan for the radiator on. OK, it might not be the sexiest of solutions, but I thought it was pretty clever and should do the trick nicely.

Mounting the Compressor

2011-08-17T17:29:00.000-07:00

The last two weeks have been exceedingly busy and it's only been these last two days that I've actually had the opportunity to begin working on the car again. Very frustrating! But I've made some progress, and I thought I'd share what's been done.

I finished building and installing the motor mount, which meant that I could finish making all the connections to the transmission; drive shaft, clutch slave cylinder, gear shift linkage, and reverse light connection. Incidentally, I was able to find the proper Bosch female connector to go with the male connector used for the reverse light switch mounted to the transmission. That was not an easy item to locate. To make it worse, apparently Bosch only manufactures them in lots once every so often because they were unavailable at every place that carried them for months, and then in a weeks time everyone had them.

At any rate, the drive line is complete, and the motor is safely tied down. It is resting on and held down to a solid piece of hard rubber designed for motor mounts. The original cross members that prevent the motor from spinning while under torque are still there, but I've added some rubber cushioning that will absorb shocks from upward travel as well. So to recap, I have hard rubber pads set to absorb any vertical bumps or vibration, and braces to keep the motor from spinning. It's not going anywhere, and it should be nicely isolated from any sharp bumps the chassis receives.

The last couple days I finished building the tray and the supports that will hold the MasterFlux A/C compressor. It's a tricky fit, just like everything else in the car. It will be suspended from the front battery tray as mentioned in previous posts, but it can't be directly under, or there would be no room to hook the pressurized coolant lines up. So it has to hang below and slightly behind the rack. Maybe a video will demonstrate it a bit better. Take a look.

I'm not sure that the shaky camera and rambling dialogue help clear things up, but hopefully you get an idea of what's involved. Afterward, I took some careful measurements of where the new hoses needed to run, and disconnected the existing hoses. I took them down to a local shop and explained what I need. I was worried that they'd want to finish the hoses on the first visit, and I'd run into problems when tying to put them in the car. Not only do the hoses need to be the correct length, but the new fittings that I need for the new compressor have to be crimped on at the proper angle so there's no twist in the lines. Apparently this is not an uncommon problem.

What they intend to do is cut the old hoses off the fitting end that I need to keep and crimp new hoses on that are a bit longer than I need. Then they'll call me in and hand me the half completed hoses and the new fittings. I can then bring the whole lot home and mount it up, cut the hose to length and mark the proper angle to crimp the new fittings on and return it to them for the final crimp. Of course I still need to find a place to mount the compressor's controller and all the supporting electronics. Truthfully, that has me worried. I have an idea of where it might go, but I won't know for certain if it will fit in that space until both battery racks are mounted back in the car.

With the addition of the new meter, and it's larger shunt, I thought I'd take this opportunity to hook things up in a cleaner way. The old set up had all of the negative lines from the high voltage side running to one side of the shunt. There was the 2/0 cable from the controller, the 6 AWG from the charger, a 10 AWG from the heater core, a 12 AWG for the DC to DC converter and a small 18 AWG for the negative lead to the meter. That's a lot so squeeze onto one terminal. So instead, I'm adding a bus bar. The bus bar I got has 4 leads, three of which will hold all those cables and wires mentioned above, and the last remaining one will be reserved for a new cable that will run to the new shunt.

The only problem is that the bus is only rated for 400 amps. As we all know, I'm looking to put 1000 amps through it. Well the reason it's rated at 400 is that there is only one 1/8" thick piece of copper tying all the connectors together. To over come this, I've made 3 new strips of copper totaling 3/16" to stack on top of the existing one, for a total of 5/16" of copper. That is more than enough for 1000 amps. That's nearly twice the thickness of the battery straps.

Speaking of battery straps, I'm taking out the original copper straps that came with the Sky Energy (CALB) cells and replacing them with the braided copper straps from EV Works. While I'm at it, I've gotten rid of all the old washers and split ring washers in favor of Nord-Lock washers. These changes will allow for two things. First, as the chassis moves around and the batteries jostle about, those braided connections will flex the tiny amount needed and not put any strain on the connection point at each battery. This will help to ensure that there is always a good connection at each terminal. To further ensure a good connection, I'm using the Nord-Lock washers. Once you've tightened down a bolt with one of those washers on it, it does not back off. Vibration or the usual expansion and contraction due to temperature changes simply won't affect them. Consequently, no loose connections, no fires.

The A/C System Has Arrived

2011-08-01T22:31:00.000-07:00

Last week, the Masterflux A/C system arrived from Revolt Electric, a full 3 weeks ahead of the initial 6 week wait they said I was in for. Fantastic news and time to get cracking on mounting it. I opted for the Sierra Model 06-0982Y3, and the 025F0140-03 controller. The controller can be driven with anything from 120V to 420V DC, and the compressor is capable of putting out over 15,000 BTU. Of course, that's when it operates at over 300 V DC. Since my pack voltage is 160, it will be putting out roughly 10,000 BTU. Should be plenty adequate for a two-seater car that has slightly more cabin space than the inside of a microwave. At full power, it will draw about 6 amps, just shy of 1 kW.

First things first. In order to mount the A/C compressor, I need to know how much room I have to work with. It's going to fit right behind the condenser for the A/C system and the new radiator I'm installing for the Zilla. But before I could measure how much space I needed to build the frame that will hold radiator and then mount it in place. Here's a shot of the radiator in it's frame:

Essentially what I built is a frame made from various angle aluminum stock. The radiator doesn't have any screws or brackets that you can use to mount it to anything. All it has is three pegs meant to hold rubber bushings that would then be pushed into some mounting bracket. Try as I might, I could not find any bushings that would fit the posts. What I did find where rubber stoppers at the local hardware store. I bought three of them and drilled a hole through each. Then I constructed the frame, drilling holes to accept the "bushings" I made and then fastened the whole thing together. It turned out pretty well. The radiator is suspended in that frame via those bushings which provide a little shock absorption for the assembly. It will be suspended from the front battery rack by those two tabs you see sticking out of the top of the rack.

Once that was complete, I put the assembly in place and just clamped it so that I could start figuring out how to position the compressor. I was very worried that I'd have little to know extra room, but as it turns out, I have loads of space. I think there may be as much as a full inch in either direction for me to play with. That may not sound like much, but trust me, that is huge. I've had a difficult time fitting very nearly every component since I started the build, running short by 1/16th of an inch here or there was way to common. Very frustrating.

The A/C compressor will rest in a tray I've made, that will then be suspended from the front battery rack as well. Here is a shot of the tray I made today:

Notice the three large holes in the middle. They are for the rubber feet that hold the compressor, which cushion vibration while it's running. The tray is 1/8" aluminum plate surrounded by 1x1 inch aluminum angle stock. It is light yet remarkably stiff. The compressor weighs about 20 lbs, so it needs to be sturdy.

At this point, I'm very glad I made that rack out of steel. It will end up supporting 12 batteries, the power steering pump, the Zilla's radiator and the A/C compressor. Fortunately it's more than sturdy enough to support all that weight, as are the brackets it mounts to in the car.

My recent experience working with steel and aluminum for all the different support structures that I'm adding is not too dissimilar than my past experience. I've found that building an EV is an endeavor that requires a great deal of care and attention to detail. You decide how and where you're going to mount something, and measure the space. You measure even more carefully, and even build cardboard models. Then you begin cutting the metal you need. Once everything is cut, you start drilling and bolting and/or welding it into it's final shape. You then go back to fit it in the car, and discover that it won't work for some completely unexpected reason. So you scrap the whole thing and start over. Maybe it's just me, but this seems to be an ongoing theme.

Next I get to build the structure that this tray will be suspended from.

On a final note, I did finish installing the new Link-Pro meter in the car. It fit perfectly, replacing the Link-10 effortlessly. I still need to find a new place for that shunt, but I'm not too worried about that.

Now That's a Shunt!

2011-07-14T12:30:00.000-07:00

There hasn't been a lot to report over the past few weeks. I've been dealing with acquiring the hardware necessary for the Air Conditioning system.

You may recall I'd ordered a Masterflux compressor and controller off a user on eBay for a bargain $200. The unit was reported to be new but old stock. In addition it required a 48 Volt DC supply. I'd been looking for how I was going to supply the necessary current to the controller at the proper voltage. Well the good news is that I've solved that problem, sort of. It turns out the compressor was not new, old stock. It was in fact used and not in good condition. The compressor had been crammed into the box along with two poorly protected controllers. Both had sustained damage while in shipment. Why the shipped two controllers, I have no idea.

Ultimately, I didn't trust either controller to work properly, and simply because of the circumstances, perhaps due to guilt by association, I didn't trust the compressor either. Everything went back.

Instead I have on order a brand new system that is designed to work directly off of my 160 volt DC system with no modifications required. The upside is obvious; the downside is it was $1200 more than the other system. Still, I'd rather spend the money and have a system that works. I don't want to mess with it once it's up and running.

In the mean time, I've been working on the revised motor mount. I cut and formed some steel and started dry fitting everything. Sadly I ran into another road block on this front. The problem I face is of course one of space. I need to get adequate shock absorption material under the motor. without any, it simply lays on the front steering rack with about 1/2" gap between the motor and the sub-frame right behind the steering rack. I need to support the motor so it's at least 1/4" off the rack so that it doesn't hit it during any vibration. More space would be better. The problem is that if I push the motor up too far, I begin to ruin the alignment of the drive line.

So, I need to find a way to support the motor in the proper position, with the proper attitude, provide shock absorption and tie it to the frame securely. I could go back with the previous solution I had, but I'd really like to add more shock absorbing material. The short story is that the pretty solution I drew up in the previous post simply won't work. Back to the drawing board.

I also started working on a minor part of the A/C system, and that was how to turn it on and off. The Z3 has a neat little button in the console with a picture of a snow flake on it. When you depress the button, it glows orange and turns on the A/C. I tried it out to make sure that it still sends a 12volt signal to the line that previously went to the compressor to turn it on, and no luck. I don't know if the ECU needed other connections from the wiring harness that are no longer there, but there was no way I could get that to power up.

Instead, I took the switch out, and started reverse engineering it. That switch also has the button to turn on/off air recirculation within the cabin. It has 8 points of connection. In short order I figured out which blade had power to it when all the right conditions were met; the A/C button was depressed, and the HVAC system fan was on. I simply spliced a new wire into that line so that I can draw 12V off it to power a new relay. That relay will turn on power to a fuse box that will provide power to the Masterflux controller and the AC condenser fan and a cooling fan for the controller itself.

I'm also taking this opportunity to swap out the Xantrex Link-10 meter I've been using, for a Xantrex Link-Pro. OK, it's actually the e-Xpert Pro; same thing. Why the change? You can chalk this up to a rookie mistake. In the beginning, when I was ordering all the parts for the car, I simply didn't understand how all of the component's specs needed to match up. I ordered a Zilla capable of putting out 1000 amps, and the Link-10 capable of reading only 500 amps. As long as I left the Zilla set to a 500 amp output or lower, then the Link-10 meter could measure the current accurately. If I set the Zilla higher, it didn't hurt the meter, but it simply didn't read the current, which meant the usage it reflected in terms of the battery's state of charge would be wrong.

Part of the package is a much bigger shunt, one that can handle 1000 amps vs. the 500 amp shunt for the old meter. Check it out...

It reminds me of Crocodile Dundee, "that's not a knife..." That thing is huge! Which raises a concern as to where I'm going to put it. I think I'll be able to fit it where the old one was. I hope. Fortunately, the meter is exactly the same size and the leads I need to power it and provide data to it are identical, so it's a straight swap as far as that goes. I did opt for one other thing when I bought the meter, and that is a temperature sensor that I'll be running to one of the batteries. I'm going to pick one somewhere in the middle of the pack, one that is likely to get the warmest. In this way I can keep an eye on the temperature of the pack during the summer heat.

One other thing I've done was to remove the gaps between the batteries I have in the box under the trunk. I'd put gaps between them so that I could force air between them if necessary. I had installed a thermal switch that would turn on and force air over the batteries if they reached 125 °F. It never came on. Plus with the temperature monitoring I will now have on the meter, it's not really necessary. But the biggest reason is that I intend to replace all the copper straps that connected the batteries with braided ones. In order to do so, I need the batteries pushed together.

So, I pushed all the batteries together and then carefully measured and cut some wood to push into the space created. Mind you, this isn't to compress the cells, but merely to keep them from moving around.

You can see it there over on the left hand side. As I'd mentioned before, and as several people have discovered, the cells do not expand unless you over charge or over drain the, rendering clamping them together unnecessary.

Motor Drama

2011-06-21T10:48:00.000-07:00

I have refrained from posting about this for a variety of reasons, but mostly because I wanted to write it up in one story once I knew the whole story. While there's no "happily ever after" quite yet, but I'm optimistic that there will be.

Sometime this last February I noticed a disturbing, but familiar feeling in the car's drive line; vibration. It started small, and I kept telling myself it was my imagination. But two weeks or so later, there was no denying it, the wobble that forced me to pull the motor a year ago was back. I was, and remain absolutely perplexed as to how this happened. I took the cooling shroud off the front and, sure enough, the balancing putty fell out the front.

I contacted George Hamstra and Netgain and told him what had happened. He was more shocked than I was. He explained that only one other motor had ever had the balancing putty come off, and that was because the owner had spun the motor up North of 9000 RPM. He went on to say that they had never seen it happen twice! Well, my motor has never seen anything over 5000 rpm, so that wasn't it. I also have cooling air forced into it constantly, so heat shouldn't have been a factor.

George talked with the folks at Warfield electric, brainstorming on what the possible cause might be. They were able to rule out the RPM and temperature possibility right away. The wondered if perhaps they had a bad batch of putty, but reasoned if that were the case, then they would be seeing failures on multiple motors since a single batch will be used on several motors. Well that wasn't happening. They speculated that perhaps it had been applied poorly. Who's to say, but it seems unlikely that it was applied poorly twice on the same motor.

George joked that "It's just you Tim!" Truthfully, I don't know that he's wrong. I explained how I had the motor mounted up in as much detail as I could. The motor was tied down to the sub-frame of the chassis with a rubber pad under it to absorb shock as it moves down relative to the car. He commented that what I described to him should be absolutely adequate. In fact he's seen installs where the motor is tied directly to the chassis with no dampening material at all, so the motor feels every shock the chassis does to no ill effect.

We were all left scratching our heads. I'm perfectly willing to accept the fact that it was something stupid that I did in the mount design or build, but I don't know what. I'm also willing to believe that the putty just wasn't applied properly, but I have no evidence that's the case. Presented with no clear cause to the problem, George stepped up and did what I think few manufacturers would do these days; he offered to fix it and cover the costs. He and his crew arranged to have the motor picked up, shipped to Warfield Electric, fixed and shipped back at their expense. I assure you this is not an inexpensive endeavor.

But then he went a full step further saying that if this doesn't fix the problem, he just wants to replace the motor. I'm speechless really. It's so reassuring to know that ultimately, I'm going to have a good motor. On the other hand, I desperately don't want it to come to that. At this point I'm certain that George has lost money on my motor, having to shipped and repaired it twice. He'd be better off never having heard of me. This is a painful prospect to me. The one way we have as consumers to vote for products we favor in the market and to support companies we believe in is to hand them our cash. I don't know of too many causes, companies or products that I support more than EVs, Netgain, and the WarP motors. So the fact that my "vote" has been nullified because of this pains me. My hope is that this is the last time the motor is out of the car for repairs. My hope is that the only time George hears from me again is when I tell him I'm buying another motor for another project. Time will tell.

So, Netgain and Warfield have done their part to try and put a reliable motor in my hands. The question now is what am I going to do? As I mentioned before, I don't know if the way I had the motor secured to the car was the cause of my problems or not. George may look at the car at the EV Converters Convention (EVCCON) in Missouri in September and say "Wait, you mounted it like this?! You fool!!" and punch me in the face. I don't believe there was a problem with the mount at this point, but I've decided there is an area where it could be improved. Take a look at this crude drawing...

This is not too different from the old support with the exception that there is now some new rubber above the angle iron supporting the motor. That additional rubber should offer additional cushion to the motor from movement. In the previous mount, which does not have that upper rubber piece, if the chassis dropped down suddenly, the motor would be forced down, incurring a bit of a shock while it followed the chassis downward. However, the new design will allow a little cushion to that shock providing some buffer to the motor when it moves both up and down. What isn't represented there is the strap that goes around the motor to hold it down to the mount, and the bars mounted from the motor to the chassis for anti-torque support.
Will this be sufficient to protect the motor? I certainly hope so. I've sent the design to George as well, looking for his input.

At any rate, the motor arrived back from it's repairs yesterday and looks as beautiful as ever. They even gave it a fresh coat of paint. I'll be mounting it to the transmission over the next couple days and dropping it back in the car. Once it's in place, I can start fabricating the new mount so it holds the motor in the right place. I'm going to be building a whole new one from stronger materials rather than adapting the old one. I think it will be easier to incorporate the change on a newer build.

Some Over Due Updates

2011-05-24T16:44:00.000-07:00

I mentioned a couple weeks back that I had some changes planned for the EV-Z3, and the time has come. I'm not going to spell them all out now. Rather I'll write about each as I tackle them, and go into detail as to why I decided the change was necessary.

Air Conditioning:

It doesn't take someone on a full ride scholarship to MIT to see why I'd want air conditioning in a car in Arizona. Last summer, I thought I'd tough it out and put up with what I remembered to be "minor discomfort" when driving cars with no AC in my youth. But I must be getting old, soft, or both because after a couple trips I'd had enough and the car started to see action only in the evenings when the temperature dropped to around 100 °F, or on rare occasions into the 90's.

You may remember that I had managed to install the original compressor into the car and planned to run it off a pulley mounted to the tail shaft of the motor. I didn't have it hooked up because the compressor was in a different place in the engine bay, and the hoses didn't reach. Well I'd just thought I'd have them remade once I was up and running. With space being as tight as it is, there was no way to do that work without taking out the batteries. It became clear I was going to have to remove the batteries in order to get AC. So, into the garage the car went and up on jack-stands.

There's an inherent problem running the AC off the tail shaft. When the motor isn't spinning, you can't compress the refrigerant in the system. I could sit with the clutch in and idle the motor, but I don't want to do that. I want a car that works normally, and not one where I hand the keys to someone and have to give them a talk about how to make the AC work properly. That meant I need to run the compressor off a secondary motor. I had bought a little 2.5 HP DC motor, originally used on a tread mill, back when I started the project, specifically for this purpose. The problem is there simply isn't enough space to put that motor, the compressor, and the metal assembly needed to hold them together into the car.

Most people into EVs have heard of or seen the small DC powered compressors made by Masterflux. Great product, and a perfect solution for me. They are small enough they will fit in the space I have. The only problem is the compressor and the controller needed to power it come in at over $1200. In the scheme of things, that's not too much, but I'd rather avoid that expense if I can. As it happens, someone is selling a number of older, new stock of these compressors on eBay at the moment. The good news is that they are asking $200 for the compressor and controller. The bad news is they require 48 volts input and can draw up to 18 amps. So, I bought one.

Now, I have no way of delivering 48 volts to the system. Especially at that level of current. A friend of mine, who is quite savvy with electronics has offered to help me build a power supply for the compressor. I know what you're thinking, and I can't really say your wrong. I'm an idiot. But I figured, the worse case scenario is that I can't build the power supply, and I simply re-list it on eBay. But if I can get it to work, I've got a great little AC unit, at 1/5 th the cost after I figure in the cost of parts for the power supply. I haven't convinced you have I? I don't blame you, I'm not convinced yet myself.

Controller Cooling:

A second big issue I need to solve is better cooling for the Zilla. The radiator I'd originally installed to cool the Zilla is 4x8 inches, or 32 square inches of area. I installed two 120mm DC fans that continuously pull air through the radiator in an attempt to keep things cool. It did just great 9 months out of the year! I had enough room for a bigger radiator, and I found one that uses just about all that space. Here it is right next to the old one.

It's 8x14 inches for a total of 112 square inches. That's 3.5 times more surface area than the smaller one. And the fan that came with it moves 331 cubic feet of air per minute, while drawing less than 5 amps. The old set up had the fans running all the time. During most of the year, and certainly when the cars moving through the air, this is a waste of energy. What I intend to do with this set up is run the fan off a thermostatic switch. I have a switch that will turn on at 122 °F, and turns off at 104. The only thing is that it's a surface mount switch. That means I'd have to find a way to physically press it and hold it to the Zilla, and preferably the area on the Zilla that gets the warmest. That happens to be dead center on the top. Hmmm... Not sure how I'm going to accomplish that without venturing into the steam-punk genre of EVs.

What I'd really like is an inline thermostat I can splice somewhere in a hose. The only problem is that all the ones I've found are for ICE cars so they come on at over 200 °F. Not suitable for my needs.

Removing some junk from the trunk:

You may recall that to monitor the batteries, I'd originally installed some test lines which I ran to terminals in the trunk and in the front of the car. The idea was that it would make it easier to test the batteries to find if they were different voltages to each other. Well, I've found that's unnecessary. Since bottom balancing the pack, I've learned which cells hit the top first when charging; and by top I mean 3.45 volts. Of course the real top end of the batteries is 3.6 volts, but the difference in the actual energy stored in a battery that's 3.45 vs one that is 3.6 is so small that it's simply crazy to try to push that extra little into the cell. Especially considering the crazy fast rate the voltage will rise above 3.6 at the end of the charge and the damage that can be done if it goes higher.

To safeguard those few batteries, and in turn all the rest of them, I have the charger shut itself off when those few cells get to 3.45 volts. If I want readings off of other cells I just take them. Having those extra wires in the car was not only ugly, but a fire hazard. So out the came.

I had installed some relays in the trunk in an ill fated attempt to turn off the DC to DC converters when the car is not in use. The problem is that those Iota converters have a large bank of capacitors in them that store energy quite nicely. So when I would turn the car back on, there was a fair amount of arching inside those poor relays, and they welded themselves shut in 3 or 4 cycles. The only reason I wanted the controllers off was that in the summer, the ambient air temperature is warm enough that their fans run constantly. Slowly, but constantly. I may address that at some point, but for now those relays and all that extra wiring was not needed. So out it came.

I also decided that I would eliminated the spaces in between all the cells in the battery box in the trunk. You are supposed to clamp all LiFePo4 batteries together between something that can keep them from swelling. Apparently they have a tendency to bulge in the middle a bit after multiple charges. Well, I'm not so sure about that. I took off all the connecting straps that I'd made so that I could leave an 1/8" between each battery, removed all the hardware anchoring them down and shoved them together. They nested up snugly, one to another just like when they were new. Keep in mind that this is after one year's worth of driving and 287 charging cycles!

Giving some thought to this, I've come to believe one of two things is going on. Either I simply haven't cycled the batteries enough to see this expansion they speak of, or my practice of not charging the cells to 100% full capacity has removed this danger. While I have no conclusive proof, I'm leaning toward the second option. Knowing what kinds of nasty things these cells can do above 3.6 V and how it affects them, it stands to reason that charging them to 3.6 V every time you charge them has got to put strain on them. Regardless, I'm removing the gaps and re-securing them in the space.

Anyway, look how much cleaner the trunk looks without all those extra wires and components.

Many more enhancements to talk about, and of course I have to document the conclusion of each of these items.

Earth Day and Some Coming Changes

2011-04-26T21:07:00.000-07:00

This last Tuesday, the Arizona Army/Air National Guard post celebrated Earth Day. They invited a number of people to exhibit everything from composting technologies to solar panels. The also contacted me and asked me if I'd bring the EV Z3 down to show at the event. I let the members of the Arizona Chapter of the Electric Vehicle Automobile Association know about it as well, hoping there might be more than just the Z3 on display.

But of course, the event was held Tuesday during most peoples work hours, so it ended up being me and Gene Cosmano with his late 70's VW truck. Gene has installed a 600 Watt solar array on top of the truck which managed to fully charge his batteries while we were sitting on the field. He's put over 200,000 miles on the vehicle since it was converted in 93. It seemed the Z3 drew a bit more attention than Gene's truck, probably because it's a bit sexier, but I have to tell you, that truck is great piece of work. I was kicking myself that I didn't bring a camera to snap some pictures.

Anyway, the day went well, with lots of people stopping by and asking lots of questions. People are always surprised to find that I use the car as my daily driver. There wasn't anyone telling me I was an idiot for ruining such a nice car, but I did hear one guy telling Gene that he should hook up some generators to his wheels so he could charge the car while he drove. Apparently the first law of thermodynamics is really only a suggestion to this chap.

On to the next topic: Changes.

For some time now, I've been planning on doing some changes and performing some upgrades to the car. Some of these are pretty extensive, so this week I'm pulling the car into the garage, putting it up on blocks and starting the work. I've put this off for some time now for a few reasons. One, the weather has been beautiful and it's been so enjoyable driving with the top down, I simply couldn't bring myself to put the car in the dry dock. But second, since it is my only means of transportation (unless I take my other car back from my teenage daughter, and no one want's that) I have no vehicle. Well, yesterday I solved the last problem by buying an older Toyota Rav4 that I can use for a few months before selling it on. The coming of summer in Arizona has taken care of the first reason; it's starting to get hot enough that driving without AC is no fun. Which brings me nicely to one of the primary objectives.

Air Conditioning! I simply can't go through another summer in Phoenix without it. I have the original compressor and a small 120 VDC treadmill motor that I'm going to try to use to power the compressor. The problem is space. There's space under the front battery pack, and I'm hoping I can fit everything in there. If not, I may be buying one of the Masterflux AC units. But at $1200 for the compressor and the controller, I'm really going to try hard to get the motor/compressor combo to fit. I also need to solve the problem with the Zilla controller over heating and going into thermal cut back. The tiny radiator I'm using to cool it is simply not up to the task, so I'll be putting a much larger one in it's place.

One of the other things I need to do is build a proper motor mount for the WarP11. As I've thought about it over time, I've realized what I'd devised and put into place really isn't adequate. But there's one problem with that. Before I had the engine pulled, I failed to get one critical measurement. Remember this for when you do a conversion. Measure the distance from the from the top of the transmission to some fixed point on the car so that you'll know exactly where it should be placed, how high to elevate it when you're constructing the motor mounts to hold up the motor. This may not be an issue on some cars, but it was on the Z3. I failed to do this, so I was left to work it out based on making sure the drive shaft fit flush to the transmission output flange. Not the best solution.

So what's a guy to do when he needs that measurement and there's no way to get it from his car? I kept an eye out on Craig's list, and when someone advertised a version of the car identical to mine, I called and asked if I could measure it. The kind person that answer that call was Frank Froncillo, owner of a company called Critical Cut here in Phoenix. My request must have sounded very strange to Frank, but he was a good sport and told me to come on down and get my measurement. He also showed my the machines at his business, which were some of the coolest CNC machines I've ever seen. They use a super thin wire charged with several thousand volts to cut through any metal stock you need with astounding precision. He handed me two pieces of metal about 2 inches thick that had been cut to fit together like a puzzle piece with absolutely no play between them. One of the coolest things I've ever seen. I found myself trying to think of how I could incorporate something he'd cut into the car. Maybe Frank could make a motor mount... Anyway, if you ever read this, thanks a bunch Frank!

In addition to those changes, I've also purchased the newest version of the Xantrex Link 10 battery monitor called the Link Pro. The Link 10 is a great instrument. It fits beautifully in the dash and measures every variable I need (though I rarely take it off the "amp hours consumed" setting). The problem is that it can only read up to a 500 amp pull on the batteries. I could buy a 1000 amp 50 mv shunt and simply multiply most of the readings by two, but that would be a pretty rinky-dink thing to do in such a nice car. The new meter will measure an honest 1000 amps and allow me to turn the controller up so I can enjoy it's full potential.

One of the things the new meter will allow me to monitor is the temperature of the batteries. Well, one battery. I'll just bolt it to a terminal on a battery in the center of the pack and I can watch them to make sure they don't get too hot in the summer. So with a solid AC system, a bigger radiator for the controller and at least some temperature monitoring on the batteries, I should be able to drive on most summer days with no problems at all. At least that's the plan.

I have a few more things planned for the down time, but I'll bring those up as I tackle them. Stay tuned, it should be fun, and hopefully we'll all learn a thing or two.

EV Car Show

2011-03-21T14:21:00.000-07:00

The Phoenix chapter of the Electric Automobile Association participated in an event this last weekend, and they asked me to bring along the Z3 for display. The event is held every year and is principally a swap meet for auto parts and car enthusiasts. But the local EV group have space reserved year to year in order to display the local member's EVs.

It was Saturday and Sunday, 6 hours long each day, and very well attended. Granted most of the people walking by didn't come to see EVs. Instead they were there to try and find the matching hub cap for their 57 Ford or something like that. Even still, a surprising number of people stopped and looked over each car and asked questions. The great thing was that a lot of these people are of the sort that have at least one car project going at all times. When they saw the home built/conversion EVs and it sparked some interest. At least 3 guys told me they were considering an EV build after seeing the cars on display. There was one guy that thought I was an idiot for having "ruined" such a great car. I should say there was one guy who openly said as much. There were probably others that thought it. But, to each his own. I hope he remembers my little EV next time he's pumping gas at $3.60/gallon.

There were a total of 3 Nissan Leafs that made it out. The owner of one of the Leafs also brought out his Chevy Volt, which he'd picked up in California just a few weeks ago. That was my first look at a Volt. Nice car, but since I didn't get to drive it, I can't comment on anything about it. There were 3 Pius's also in attendance that had been modified to have approximately a 40 mile range on battery power alone. Here's a smattering of some of the other cars that made it.

This is Sam's Chevy S-10. He's got 200ah GBS lithium batteries under the bed, for a range of over 100 miles.

Jim's Fiero has flooded nickle-metal-hydride batteries. Jim had two vehicles there, the other being a Chevy S-10 that was purpose built as an EV by Solectra.

Abe and his Dodge Neon. Abe also owns the Ford EV Probe that I'd shown back in November from the SRP Party For the Planet event we both attended.

Rick's EV Saturn. Right now it has flooded lead acid Trojan batteries in it which Rick says have all but died. He's got plans to upgrade to Lithium soon which will really add some distance to the range the car has. He's also taking delivery of a Leaf in April.

I didn't get the chance to snap pictures of all the cars, but it was really rather impressive. What surprised me were the number of people that had, or will soon have, more than one EV. Six, by my count! That helps to strengthen the my argument that we should get an EV for our teenage daughter :) She only drives 8 miles a day, maximum, so an EV would be perfect.

Driving the car clear out to Glendale (a 32 mile trip) was completely worth it. I had a great time, got to show off he Z3 and meet some other genuine EV enthusiasts.

The Z3's One Year Anniversary

2011-03-02T00:01:00.000-08:00

It was one year ago today that the Z3 rolled out of the garage for the first time as an EV. Since that day a lot has transpired. Some of what I've learned you may find interesting or perhaps even useful in your own EV adventures. With that in mind it seems only appropriate that I take some time here to recap what the first year of driving the EV Z3 has been like and discuss what I've learned as a result. So grab a refreshing beverage, perhaps a light snack, kick back and enjoy the read.

Technical Issues, good and bad:

From the first tests of the car, I found that the car was much slower than expected. Zero to 40 was 20 seconds or more, and 60 mph was a distant dream. It just didn't make any sense. After all I had a 1000 amp controller and a WarP 11 motor! I had set the controller to limit the current to only 500 amps at first, but I could see on the Link 10 meter that it never seemed to draw more than 250 amps. I gathered data from the Zilla's output and ultimately forwarded it off to the experts, only to find I'd made a relatively common mistake. I'd set the low voltage battery indicator (LVBI) parameter too high.

Interested in protecting the batteries from being discharged too far, I'd set that parameter to 140 Volts, which is just under 3.0 Volts per cell. I had no idea that the battery pack's voltage would sag below that under the first real load. The whole thing would happen so fast. I'd press on the accelerator, the voltage would drop, the Zilla would cut back, all within a second or two, so I never even experienced what full throttle felt like. The Link 10 didn't even have the time to display the low voltage before the Zilla would cut the current back and the voltage would recover, so it remained a mystery to me.

Once I was set straight and advised to set the LBVI closer to 110 volts, the car behaved more like I would have expected. But not quite. Zero to 40 is now somewhere around 5 seconds with the car hitting 60 mph in 11.5 seconds. That's not as fast as I would have liked but absolutely tolerable. I still wasn't sure why that was the case, but I discovered why in due time. Being new to this entire endeavor, I had no idea how to size a battery pack, nor how a batterie's "C" ratings can affect you in the real world. As it turns out these CALB cells can sustain a 3C output. I have 120 amp/hour cells, which means that they can only put out 480 amps sustained. That means the Zilla never really puts out the 1000 amps it's capable of. Ok, it might for a second or less, enough time to spin the tires for a moment, but no more, I assure you.

If I had the chance to do it all over again, I'd choose the 200 amp/hour cells and figure out someway of fitting them in the car. That would get me a sustained output of 800 amps, a much more attractive number. However, until such time as I receive a hefty windfall of cash, I'll be keeping the 120s.

After all that was sorted out, I had roughly 1.5 months of trouble free driving. But toward the end of April, I noticed a vibration in the drive line. On April 29th I had to put the car back in the garage and remove the motor and transmission. I ended up finding that the motor had come out of balance in what was described by George Hamstra of Netgain motors, as a very unusual situation. The balancing putty had come off the armature. Like a hero to the rescue, George had me ship the motor back and they fixed it up as good as new in record time. I decided to take the opportunity to redo the battery layout in the front. That extended the down time to two months, so the car was not back on the road until June 30, the middle of summer.

As you might have guessed, the middle of summer is pretty hot here in Arizona. Hot enough that driving a car without AC is down right unpleasant. I still hadn't hooked up the AC compressor, so that meant no cold air. Taking the top down isn't really an option because then it's still hot and the sun is hitting you. But the bigger issue was that the Zilla controller began complaining that it was getting too hot. The ambient temperature was close to 120 °F, and the Zilla's first thermal cutback is 131 °F. As you might expect, it took almost no time at all for the Zilla to reach that. It only cut the output to 75% at that temperature, but I was surprised how much of a difference that made. But the larger issue is the potential for damage over time. The cooler electrical components are, the longer their life, and the last thing I want to do is compromise the Zilla's health. A larger radiator might help dissipate heat better, but realistically, I don't think I can hope to keep the controller under 131 °F in the middle of summer.

I'm afraid that isn't the only heat issue. I've taken a few temperature readings of the batteries, starting when they'd been sitting over night and were at ambient temperature, and then reading them again after a 12 mile drive. I did this a couple times this winter when we had some unusually cold weather, temperatures in the low 20's. I was concerned the low temperature might affect the batteries performance, but I was pleased to find it didn't at all. The car performed no differently than when it's 80°s outside. What I did find, however, was that the batteries rose between 15° and 20°s over the course of the trip. Well, that could be a problem.

Imagine, if you will, that the weather report says it's 115 °F out. I can tell you from experience that when they say it's 115° at the airport, it's over 120° on any given surface street around town. That means in a relatively short period of time, the batteries are going to be at or above 120° just from having the air blow over them. Couple that with the potential 20° rise in temperature from use, and they are now between 135 and 140°. Well, 140° is the magic number for these batteries where the organic solvent used as an electrolyte starts to decompose. Bad news if I'm trying to preserve the longevity of the batteries. Now imagine that I've hooked up the AC compressor, and the excess heat thrown off from the condenser is flowing right over the batteries just behind it. You may be recognizing the predicament I face.

It looks like normal daytime driving during the hottest days in the summer is perilous at best, with temperature risks to both the batteries and the controller. Throw the AC system into the mix, adding more heat to the equation, and it becomes downright irresponsible. Sadly, I think this all means that I'll have to eliminate driving during the hottest parts of the day in the summer. Hopefully I can get away with some driving at night. But of course that means that there really is no point in hooking up the AC compressor either.

Once summer was over I started driving the car on a daily basis. It has been completely trouble free. I start it (or turn it one, would be a more accurate phrase) and then drive it. No worries, and no troubles. It's wonderful!

In an effort to be straight with you, I've shared all the difficulties I've had and the ones I'm still facing. The problem is that last paragraph, the one tiny one about how great the car is to drive, seems almost lost in comparison with the less than ideal information before it. It's difficult for me to give that last paragraph the weight or emphasis it deserves. The problems I've had pale in comparison to the joy I experience driving the car day to day. The strong torque at start up, the smooth quiet acceleration, driving straight past gas stations, all these things add up to an experience that is hard to convey with words. It's sublime, and it needs to be experienced to be fully appreciated.

Community Engagement:

I've had the opportunity to take the car to two car shows, and it was well received at both. There must have been around 100 people between the 2 shows that approached me to ask about it. I've had about 8 visitors come by the house to look at it; 2 local people and 6 others that had come from out of town. I've had a few people ask me about the car while I was driving in the neighborhood, or in local parking lots. You may have read just last week that I took the car to ASU to show some engineering students. The reactions are always the same; people love the car. The questions are always the same, how far does it go, how long to charge it. Everyone seems amazed to find that it is my daily driver. The best thing about showing the car to people is that they start to see the possibility that an EV is a viable option. You can always tell the ones that are the most skeptical of the technology. To them I explain what I've always felt, and that is if a family or person has two cars, then the odds are that one of them could be electric and they would suffer no inconvenience in their lives.

Battery Report:

Here we are, one year after the car rolled out of the garage without a BMS and the batteries are fine and the car works just as it should. I had people warn me that I needed to put a BMS on the batteries or they'd be ruined in no time at all. Clearly not the case.

I did have the one scare back in September where I monkeyed with the charger and over charged a couple cells by a bit. They may have been damaged, but so far they've shown no signs of damage. I expect that years from now when the pack has 150,000 miles on it. they might be the first to show signs of decreased capacity. But that incident was entirely self inflicted! I recovered in short order, and learned a lot in the process.

Last month I bottom balanced the pack. I checked the battery's voltages every time I charged them for the first couple weeks. I found that the charger is cutting off when the highest battery in the pack is at 3.47 volts. Well below the 3.6 volt ceiling that CALB recommends. Even with that very cautious and conservative charging regime, the batteries are still holding 119.5 amp/hours. I'm playing it safe, charging carefully and not over discharging the batteries and they are fine. End of story.

Statistics and other Damned lies:

Our illustrious leaders often use statistics in questionable ways, slanting them as support for their agenda. I'm going to see if I can avoid that. I don't really have an agenda after all.

I keep a spreadsheet of every aspect of the car that you can imagine. I'm not normally so obsessive about such things, but I figured if I was going to understand how cost effective, or in-effective this whole endeavor is, I needed accurate data. So every time I charge the car, I make a note of the miles I've driven, and the amount of power I used. It's yielded some very interesting information. I've also kept data on each individual battery in the pack. That has yielded absolutely nothing interesting. Well to be fair, the fact that it contains nothing alarming is interesting, but it is the only interesting thing about that data.

Lets get to it.
4233 - Total miles I've driven.
1648 - Total kWh's I've used.
389 - Average number of Watts/hours per mile consumed.
192 - Total gallons of gas I didn't use.
$506 - Total amount of money I've saved using electricity vs. gas.
$0.03 - Mean average cost per mile.
20.4 - Mean average number of mile traveled per charge.
39.1% - Mean average depth of discharge.
39.6% - Median average depth of discharge (for all you statistics nerds).
46.3 - Mode average depth of discharge (for all you hopeless statistics nerds).
212 - Number of charging cycles.

Here's a chart I put together which is just plot points showing every time I've discharged the batteries and to what depth of discharge (DOD) I took them. Note that there is no declared value to the X axis on the chart, though it is actually date related with the far left being the first charge. Also note the one point higher than 100%; that was when I took the pack down to near depleted so I could bottom balance the pack (it gave up 127.5 amp/hours or 105% of it's stated capacity).

I'm sure you'll notice a grouping around the 55% DOD level. Those would be my drive to work. Some notes on the data. In the formula I've used to figure out the cost the electricity I've used, I'm factoring in 10% loss in the systems due to the normal inefficiencies of converting current. That may be a bit heavy handed, but I'd rather err on the conservative side. When I drove out of the garage last year, gas was at $2.75/gallon for premium (that's what the car required before the conversion). Yesterday I drove by the Costco near my house to find out how much it is now: $3.49. The funny thing is I had to walk up and ask because they don't have it posted on a sign. I'm not buying gas very often these days. The average Watt/hours per mile of 390 might seem kind of high, but that's because a good portion of the miles I've put on the car were done on the highway at 65 mph when the car averages about 410 Watt/hours per mile. If I drive at 45 mph, the car gets closer to 320 Watts/hours per mile.

Oddly enough I got a very interesting and timely piece of mail today. It was from my power company detailing my power consumption over the past year, comparing it to my power consumption the previous year. Like I said, timely. But as we're not talking about a controlled experiment, the numbers are only interesting, not indicative of a trend associated with the car coming online. As it turns out, we used more electricity in 2009 than in 2010 during the period when the car was operating; 5 kilowatt/hours more to be precise. But I had switched to a Time of Use plan when I started driving the car so I could take advantage of off peak power rates. As a result, we saved over $72 this past year on our power bill compared to the previous year. Interesting, but ultimately not really related to the car. It is noteworthy though because one of the arguments people use to dispute the advantages of EVs is they say your power bill will go up by a lot. Hmm... that doesn't seem to be foregone conclusion does it?

Let's go for a ride:

I thought it might be nice to take the car for a short drive and film it so people can get a feeling for what the car's like. Take a look.

The video quality is pretty poor, but at least you get an idea of what it's like to drive the car.

Conclusion:

So the question is "Has it been worth it?" From a project point of view, yes. It was a terrific project and I enjoyed nearly every moment working on it (I did crush my finger badly and that wasn't much fun). While I intended to build it in such a way that I wouldn't have to tinker with it after I was done, I find myself tinkering with it anyway because I enjoy working on it. It's become an enjoyable hobby.

Has it provided me with reliable transportation? Yes. Like I said before, I turn it one and drive it, it's that simple. Has range been an issue? Three times in the last year while traveling in the city I've needed to go further than the car would take me, so I had to use my gasoline powered car. The other three hundred plus trips I've made I used the EV. So, has the 60 mile range been an issue? Yes, less than 1% of the time, range has been an issue. Not bad odds.

Do I experience range anxiety? I did for the first couple months, but slowly realized that it just wasn't an issue. It simply requires one more step before you leave the front door. You get your wallet, phone, keys, sunglasses, do a quick sum of the distance you need to go if it's someplace you haven't already been, and then walk out the door satisfied that all is in order. I used to watch the amp meter like a hawk. Now I just tend to look at it when I pull in the garage so I know how much power I used so that I can record it in my spreadsheet.

Did it make sense financially? Not really. Or perhaps I should say, not entirely. If I were to go buy a Nissan Leaf, I'd pay roughly what I paid for this car. I'd have a car with all the environmentals that one would want in a desert, plus a warranty! But let's face it the Z3 is prettier. I could have kept the ICE in the car and not spent the $23K to convert it. You can buy a lot of gas for $23K. However, slowly and surely, the car will save me money; $506 this year, and likely more this coming year judging from the rising prices of gas. Will it pay for itself? Will I make the money from the conversion back in gas savings? I sure will. If gas rises to $4.50 a gallon, I'll make the conversion cost back somewhere around the point I've put 135K miles on the car. When you take into account the decrease in maintenance costs that comes down a bit, but you get my point. You don't convert a car because it's going to save you money. At least you don't convert a Z3 for that reason.

Everyone who's ridden in the car exclaims how much they love it. Everyone who's driven the car, at some point and to some level, express how they now get it. They understand why people who drive electric cars like them. They leave thinking of the possibility of owning one themselves. Will electric cars take the world by storm? I'd like to think so, but I don't think they will. It will be a slow, steady adoption. But I'm certain that the people that go EV, will likely not go back.

Pat yourself on the back for making it through the longest post I've ever written. I hope it was informative and interesting to read. Thanks to all who've read the blog over the past couple of years and to those who've posted comments, questions and advice. I'm glad to be a part of this community.

A Visit to Some Student Engineers

2011-02-25T08:23:00.000-08:00

A couple weeks ago I was contacted by an engineering student at Arizona State University. He told me that he and his fellow students had been working on a Geo Metro, trying to turn it into an electric dragster. An unusual choice I thought, but they'd bought the car after someone else had already converted it to electric drive, and they were simply going to modify it and improve it.

He asked if I'd be willing to bring the Z3 down and let them look at it, and perhaps give a short presentation on the car. I wondered what I could possibly share with engineering students that they didn't already know, but I said I'd go.

When I arrived, I pulled the car around to a spot outside their work shop and opened it up. As a crowd started gathering around, they started asking questions about the car. Soon an older gentleman joined them, clearly not a student. His name was Jim, and he explained that he was the head of the program. Once all the members of the team showed up, I started running through the various systems, explaining how each worked and why I built them the way I did. I tried to be as honest and informative as I could be, showing the things I thought turned out well, and detailing the mistakes I'd made along the way.

The group was clearly interested and began asking more questions. There were the normal question, "How long to charge it?", but also more technical questions like "How do you keep the motor from going over it's RPM limit? Do you have a sensor on the motor?" Occasionally Jim would prod them, "See how he did that?", or "Look at that." All the while, he took careful notes. A couple of times, the group would say, almost in unison "Ohhh" leading me to believe that they'd seen the answer to a problem or question they'd had. In general, it seemed to be worth their time to look it over.

After I'd shown them everything I could on the car, they offered to let me see their project. The car had come with a Netgain 9" Impulse motor, powered by a Zilla 1K controller and a bank of AGM (absorbed glass mat) batteries; a type of flooded lead acid battery. I don't know what the original configuration of the batteries was, but I gathered they were going to re-do the layout with all the cells in the cabin on racks along the floor of the car. It was now going to be a single seater; after all, you don't need a passenger when you race. They've got everything out of the car and their cleaning it, prep-ing it for paint and to receive all the components again.

After wards, Jim offered to give me a tour of their facility. That's when I found out these students weren't part of any average engineering program. ASU has put together an Automotive Engineering program designed to address all aspects of the automotive trade. Jim is a retired GM employee who had worked at GM proving grounds on the Corvette team. He took me through the building showing me the CNC machines, their full machine shop, automation and electronics room, materials lab, welding shop and casting shop. Yes, a casting shop where they cast parts in sand molds with molten metals. How cool is that!? I walked through the building with an increased sense of wonder and jealousy of all the students there. Jim's been hired to build out the program and part of that is building and supplying the facility with all the tools the students will need to learn what goes on in the industry and how to fit right in to it.

All in all, it was a great visit. I was very grateful for the opportunity to see the facility and what they do. I hope the students learned a thing or two looking at the Z3 that might help them with their project. They promised to invite me back when it hits the road. I sure hope they do.

Balancing Act

2011-02-09T15:42:00.000-08:00

For the past 4 months, I've been waiting for a break in the action so I could do a proper bottom balance on the battery pack. Well, the opportunity presented it's self this last week with some time off work and fewer than normal tasks that required my attention. But as fate is fickle, and sometimes cruel, I came down with a case of the flu which added a whole new level of unpleasantness to what was one of the most dull and tedious experiences I've had in recent memory.

A word on balancing; why do it? Strictly speaking, I supposed it's not necessary. However, it does provide you with a reference point about your battery's state which can be quite useful. All BMSs balance the batteries at the top of the charge. This, in an effort to make sure they are all fully charged and you get the most out of your batteries. But this is not without it's dangers. The alternative would be to balance the batteries at the bottom of the charge curve.

Try as you might to get a pack of batteries that are all identical, that's not going to happen. There will be variations in their capacity, however slight. What this means in practical terms is one of the batteries will either be charged to 100% before the rest, or discharged 100% before the rest. Without balancing, you can see both events could occur during one charge/discharge cycle even if one is careful. Since the real danger to these batteries is over charging or over discharging them, you've got danger at both ends of the spectrum. If you balance them to one end, you can make sure they all reach full at the same time, or they all reach 100% discharge at the same time, you've eliminated the danger on one side equation.

So now it becomes a question of where you want to balance the cells, top or bottom. Pick your poison as they both have their perils. The down side to top balancing is that you run the risk of having one or more cells hit rock bottom first during a discharge. If you aren't aware of it, and don't do anything about it, you'll drive the cell into reversal and kill it, followed by the next low cell. Generally considered bad. But in addition to that, you also have to trust that the BMS isn't going to malfunction at the top of the charge and let one or more cells run too high. Also bad, and there are multiple incidents of this occurring resulting in fires, wholesale destruction of the car and anything near it.

Bottom balancing means you make sure all the cells hit bottom at the same time. The advantage is you're not going to kill one or more cells due to imbalance at the bottom. The disadvantage is that you must set your charging algorithm up to accommodate the imbalance at the top. This, as we'll see, is easy and only has to be done once. So, we have a choice fraught with danger during every charge and every discharge, or one that needs care in setting up and then no down side. The choice seems obvious to me.

The goal was to take every cell down below 2.74 volts. The CALB batteries are considered dead at 2.0 volts, but the difference between 2.0 and 2.74, in terms of the amount of power stored in the cell, is trivial. In addition, 2.74 is over the knee on the discharge curve and a hop away from dead. Once at 2.74, I intended to charge them back up to 2.750 volts. Once they were all even, charge them. Seems simple right? In concept, it is. Executing the plan proved to be a bit more challenging.

Let's take a look at the tools of the trade:

At the bottom of the picture is the DVM, or digital volt meter. No surprise there, any self respecting person should own one of these. This one is accurate to 1/1000th of a volt. Well, it displays to 1/1000th of a volt, but I have no idea how accurate it is. I do, however, believe that it is consistent. So even if it's off in it's readings just a bit, it's off the same amount on every reading, so that will do. Just above that and to either side of the photo are two very sophisticated pieces of equipment used to draw power out of the batteries, otherwise known as automotive lamps. Others may use a more elaborate and expensive piece of equipment, and they are probably very useful, but I don't have anything like that, so lamps it is. Above those and at the top of the picture is what's commonly called a bench power supply. This little device can put out any voltage between 0 and 18 volts and any current between 0 and 3 amps. I'll use that to charge individual cells.

I had gone for a particularly long drive and I'd used about 98 of the 120 amp/hours the batteries hold. I decided to take a few laps around the neighborhood, and once I'd drawn out a total of 115 amp/hours, I pulled into the garage. I then measured every battery and found the 4 lowest cells. They were each just over 3.0 volts. I turned the car on, turned the heater on, got my DVM ready and started measuring. I kept my eye on all the cells, but paid particular attention to the 4 lowest ones. It became clear in a short period of time which one was dropping first so I focused my attention on that one. By the time it got to 2.74 volts, there were still several other cells right near 3.0 volts. I decided to add some current to that one cell and get it up to 2.9 volts. It took about 10 to 12 minutes, with the bench power supply set at 3 volts and 3 amps. That worked out pretty well, so I turned the heater back on to bring them all down.

By the time that cell reached 2.70 volts, a few others were just below 2.75 with the rest in the 2.8's and 2.9's. I would need to draw the power out of those individually. But when it was all said and done, the 120 amp/hour CALB cells had given up 127.5 amp/hours of current. Not bad, not bad at all. I threw the big red switch isolating the battery pack from the car and began working.

I went through all the batteries again, recording the voltage on each. At that point, I began identifying which needed some extra power pulled out and how much I'd need to pull out. Starting with the first battery in the pack, I clipped the lights to the terminals and watched with the DVM. The lights issued a nice warm glow as they ate up the power. When the DVM read 2.65 volts, I unplugged the lights. The meter immediately began to rise and within 5 minutes it was over 2.75. Ok, so 2.65 wouldn't do, how about 2.60? That showed more promise, and I proceeded through about 5 batteries in this manner.

It was very slow going as it took anywhere from 15 to 30 minutes to drain each battery. But then I realized that I could do more than one at a time if they were adjacent to each other in the series. At that point, I started working in groups of 2, 3 or 4 batteries at a time. The more batteries I hooked up to the lamps, the brighter they glowed. Worked perfect.

What didn't work perfectly, or I should say, what I didn't expect was how much the batteries would recover after I got them down to the 2.74 mark. It took me two days work, to get through all the batteries. When I'd finally got the last one down, just below 2.74, I went back and started measuring the cells at the front of the pack, only to find that they'd recovered and were now all hovering around 2.76 to 2.82 volts. Ok, this was going to require another pass through the whole pack taking them down perhaps a tad further. But before I did that, I decided to run a quick test. I worked with the first 4 batteries, and recorded the voltage of each. I decided that I would leave the lamps on the battery for 10 seconds, plus 5 seconds for every 1/1000th of a volt over the target. Once I was done drawing off the power I left them over night and came back to measure them in the morning.

The next day, with the flu in full swing now, I dragged myself out to the garage and took measurements on those cells. Each was between 2.74 and 2.75. That did it!! Next I simply had to work my way through the rest of the pack. That took a few hours, but as I'd learned, I had to let them rest for a while before I could get an accurate reading off them. Since I felt horrible and was in danger of covering every battery with plegm, I decided to call it a day and start fresh in the morning.

Next morning they all looked perfect. Now came time to carefully charge each up to the 2.750 target I was looking for. The short story here is that I got the first 18 or so to that target voltage, and went in for the night. I basically charged them up to 2.83 volts each and watch them settle back to 2.750. However the next day when I came out to continue with the remaining 30 cells, I'd found that all the batteries that had been at 2.750 had crept up and were all over the place. The lowest was at 2.758, the highest at 2.810. What the...

This is when the notes I'd been taking became very useful. I found that the ones that had crept the highest were the ones that were on the charger the longest. Even though a particular cell might have settled to 2.750, if it took more energy to get it there, while resting over night the voltage climbed higher than one that had needed less energy to get it to the target.

So what was the magic formula? I can't really tell you because as I worked I got more in tune with the batteries and what they needed. It really was a very touchy-feely operation. But I can tell you with conviction that what brought me success was recording everything I did and how the batteries reacted to them. I could start recognizing patterns and figure out how they would react to any given charge or discharge. Plus, you simply must give the batteries time to settle once you've worked with them; 6 hours is good, 12 is better.

What I also found was that getting the cells to 2.750 volts at 11:30 at night when it's cold means that they will rise to 2.756 or so when the day warms up. I can also tell you that getting them all to the same 1/1000th of a volt proved more of a challenge that I was willing to endure. I settled for a spread across 2 1/1000th's of a volt. I'd say that's acceptable in anyone's book. So yesterday morning, I took measurements of all the cells and found, after they'd rested all night, that every cell was 2.752 or 2.753 volts. The entire pack measured 132.1 volts. Time to charge.

I was particularly interested to see how much current they'd accept at this point. I threw the big red switch connecting the pack to the car and the charger, plugged in and ramped up the current. I set the charger for the highest setting it can muster and it was putting out 29.0 amps. That went on for three hours, when the voltage got high enough that the charger said "we're done" and shut off. Well, I knew we weren't done and I expected that. Those who've read my experiences from last September and the lessons I learned from Ohm's law will remember. I hadn't touched the voltage potentiometer on the charger, so it was reading a higher voltage than the normal shutoff voltage I've selected since I'd set it for more of a lower 15 amp charge. Increase the amps to the batteries, resistance goes up, consequently voltage to push that current goes up and the charger reads that as a full pack and shuts off early.

This was all fine and anticipated. I turned the charger back on and turned the current down to 20 amps. About 2.5 hours later the charger started to tell me it was near done. I measure each of the batteries and found that they were anywhere from 3.390 and 3.43 volts. I wrote down the four cells that were highest with the intentions of watching them carefully until the end of the charge.

I turned the charger off, turned the current knob down and started it back up again. This time I turned it to 15 amps, which would be a full charge on the batteries before I'd done the balancing. I wasn't sure how much time was going to pass before they were done, but I needed to stay with them, measuring the whole time to be sure no cells went over. As the batteries approached their normal cutoff voltage of 164.7 I'd set the charger for I was measuring every cell in the pack, starting at the front, working my way through them and starting over. What I found was that the 4 I'd originally ID'd as showing a bit higher voltage remained slightly higher of the others the whole way. That is until just right before the charger reached it's cutoff when one cell stuck it's head up and hit 3.45 volts before any other. Five minutes later, the charger indicated that it was going into constant voltage mode and started to ramp down the current.

No cell went over 3.46 volts, well shy of the 3.6 CALB states is the top end. In fact the highest cell went to 3.48 volts. That leaves me plenty of wiggle room between the charger's cutoff and the top of the batteries. When all was said and done, the batteries had accepted 119 amp/hours. That's 1 amp/hour shy of their reported capacity and a full 8.5 shy of their demonstrated capacity. But I'm fine with that because that means I can plug the car in, walk away, and remain confident that batteries will charge up to near their full capacity and not burn down my car or house. That said, I don't intend to do that for a few cycles. Not until I'm sure I'm seeing consistent behavior from all the cells.

There you have it. I hope it wasn't as tedious to read as it was to experience, and I hope it offers some information to others planning the same thing. In a few months, I'll run the batteries down again and see how well they've done staying in balance relative to each other. Should be interesting.

A Trip to the Local BMW Dealership

2011-01-19T11:50:00.000-08:00

Last week, I was out running some errands, and enjoying the beautiful top down weather we've been having here in Arizona, when I found myself near one of our local BMW dealerships. I've mentioned before that a number of people have encouraged me to take the car to BMW thinking they would be very interested in seeing it. I thought about it for a moment, realized I had a half hour to spare, and decided to stop.

I figured the best way to break the ice, so to speak, would be to ask if they had any information about their EV program. There's been plenty of things mentioned on the web about the Megacity, and the potential of putting an electric BMW 1 series into production, so you can imagine I was a bit surprised when the salesman said they knew nothing of any EV programs within BMW. "Huh, you don't say?" I didn't see any reason in informing him of the programs they are working on.

I told him that I was interested in an electric BMW, so much so that I built my own. He seemed a bit surprised and mildly interested. He asked if the engine kicked in after the batteries were depleted, and I explained it no longer had an engine. That surprised him, and he said he'd like to see the car.

We walked out into the parking lot and I showed him the car. I pointed out how it was impossible to tell the car had been altered from outward appearances. After looking at it for a moment, he exclaimed that he had to go get others to see it. In all, about 7 different guys came out to look at the car. A few asked the usual questions, but only 2 really seemed interested in it. Within 5 minutes most had waked away, but the gentleman I'd met when I walked in stayed and continued to ask questions. He asked if I'd be willing to bring it back by when one of their traveling technicians was in town. He felt certain this technician would like to see it, so I told him I would.

Over all, it was a pleasant experience, but pretty much what I expected. No enthusiastic commitments to pass the information up to corporate, or anything like that. Nor were they completely uninterested in the project. It just struck them as an interesting peculiarity brought to them out of the blue. I made it clear that the car worked fine in day to day traffic and that it was my daily driver. I hope it impressed upon him the reality that EVs do have the potential to be a successful, useful addition to any garage, but who knows. What I do know is I'm looking forward to whatever BMW does come out with for the EV market. But then I'm also interested in the Tesla Model S, Audi's E-tron cars, and VW's electric Golf among others. My hope is that inside of a couple years, there are going to be a number of great EVs to choose from.

What I've Learned This Year

2010-12-31T12:09:00.000-08:00

You may have noticed that I haven't posted anything in a while. That's largely due to the fact that nothing interesting has happened in a while. I'm pleased to report the Z3 continues to zip along trouble free and in relative quiet (still can't find that pesky rattle). People occasionally ask me about the car, but I haven't had any interactions that are worth mentioning lately. I've had a number of people tell me I should drive it down to the BMW dealership nearby and show it to them. I'm kind of torn on this, I can see it going one of two ways. One, they are interested and a few people come out to look at it. Or two, they don't give a damn and are irritated that I'm taking up their time and not there to buy a new car from them. I'm just not sure it's worth my time.

The batteries have been a complete non-issue. Meaning that I charge them, I discharge them, and they do nothing out of the ordinary or unexpected. I still need to bottom balance the pack, but I simply haven't had the time, what with the holidays and all. However, I have had time to think about it and draw my own conclusions on the topic.

As I see it, bottom balancing means I'm not going to run the risk of ruining one or more cells by driving them to reversal if I draw the pack down too far. So that's one argument for the case. I may not be able to charge all the cells all the way up if they have slightly different capacity, but that difference is so minimal, it has almost no impact on range; less than a mile, probably 1/2 a mile at worst. I may have to tinker with the charger to make sure it cuts off at the 3.45 volts I've been using, but so be it. Having to set the charger for the proper cut-off is necessary regardless where you balance the pack, top or bottom, or even if it's not balanced at all. So that is not a factor. If we tally that up, we have one positive and two non-issues.

If I top balance the pack, I can be sure all the batteries are fully charged at the end of a charging cycle, which gets me nothing really. I may be able to squeeze out that extra 1/2 mile I mentioned before, but there is always the ever present danger of reversing a cell or two if I discharge too far because some hit bottom first. Setting the charger for the proper cutoff still has to be done, so that's not any different from bottom balancing. So, that's one strike against top balancing, and two non-issues. If you weigh it up, you see where the balance falls (no pun intended).

I learned something about Ohm's law in September. I had no idea why turning down the current I was charging at would push the batteries to too high a voltage. To be clear, I had no idea it would happen, and after it did, no idea why! I tinkered around with the charger settings for a month before I understood what was happening, but still had no idea why. Jack Rickard was kind enough to explain it to me and mentioned that even he'd fallen victim to it. I suggested to him that if we both had been bitten, others might as well, and that he may want to mention it on one of his weekly shows. Boy did he! Fully half of one of his shows was dedicated to showing how I messed up and explaining why it happened. To me, this may be one of the best shows he's published. If we can point out the land mines involved with these batteries, hopefully people won't step on them. They really are the best solution for enthusiast, home built EVs at this time. Fortunately, the batteries are robust enough to withstand even my clumsiness. Dr. Jay Whitacre pointed out that as long as the cells are not charged above 4.3 volts, they are more or less unaffected. Mine never came close to that kind of voltage.

From the time the car rolled out of the garage until roughly two months ago, I watched the Link-10 meter like a hawk, and range anxiety was a real issue for me. I suppose that watching the meter over that time was necessary for learning purposes. But eventually what I learned is that there really isn't much reason to watch it at all. I know how far the car will go, I know how far my trips are, so range anxiety is really not part of my reality anymore. This year I've come across only a handful of instances where I needed to use my ICE car instead of the Z3. Most of those times it was because I needed to carry more than one person. One of those was because I needed to carry some 2x4's home from the hardware store (tough to do in a Z3). I can recall only one occasion where I needed the ICE because I needed to drive across town and range was an issue.

Summer was tough. It was too hot to drive the car because there was no AC. The Zilla kept flashing at me warning that it was getting too hot. I'd back off the throttle, or coast,a bit and the Zilla would stop complaining. I can fix the AC problem, but it will involve removing the batteries up front and hiring someone to come out and fabricate hoses for me. I could throw a bigger radiator at the Zilla to dissipate heat better, but I'm not too sure that would be very effective when the air is 120 °F or hotter on the street. I may try, but it may be a mute point as I'm about to explain.

My real concern is the batteries. They typically warm up to between 15° to 25° over the ambient air temperature, and that's the temperature taken at the terminals, internally it's bound to be warmer. I have no idea how much warmer, but it's probably on a few degrees. They all have plenty of airflow around them, but there is only so much cooling 120° air can do. The problem is the electrolyte in the cells starts to degrade between 135° and 140 °F. It's easy to see how that temperature can be achieved in the Arizona summer if the batteries run 25° hotter than the ambient air. Keep in mind that when you hear that it's 110° in Phoenix, that's at the airport. If you actually measure the temperature of the air over any surface street in the valley, it's going to be North of 118 °F. Heat is the second biggest threat to these batteries, and unfortunately summertime in Phoenix has that in spades. I may very well end up using the car only 9 months out of the year, which is too bad.

There you have it; the good and the bad, the ups and the downs. Nothing really earth shattering on either side of the spectrum, and I suppose that's good. I was shooting for a car that I could just charge and drive, relatively worry free, and that's pretty much what I got, now that everything has settled down from the motor problems in May and the charging problems in September. I've put over 3150 miles on the car. It has become my daily driver. It's rare that I have to drive my ICE car. I've said this many, many times before and I think that manufacturers need to use this logic when selling EVs, If you have more than one car, the chances are very good that one of them could be an EV and you wouldn't notice a difference in your life except that it would save you money in the long run. If you have more than 2 cars, then it's an almost certainty that one of them could be an EV and you'd never feel any inconvenience apart from a heavier wallet.

When we get to March 2nd, the anniversary of the Z3's road debut, I'll publish every sordid detail and piece of information I can find on the car. I've been keeping tabs on quite a lot of data, and I'll share it all then. In the mean time have a wonderful new year, and thanks for reading!

Test Driving a Leaf

2010-12-03T11:37:00.000-08:00

Today was the day I had signed up to test drive the Nissan Leaf. Every year around this time, the city of Tempe has a street fair with artists and artisans displaying their wares for Christmas shoppers. Nissan set their tents up in and advantageous spot adjacent to the fair, sure to get a lot of traffic.

Once I arrived and was checked in, I had to wait about 15 minutes before the next group of people were taken on the tour. I, and all the others were walked through three different tents each designed to educate you on a specific aspect of the Leaf.

First was the technology tent. They explained the Leaf has a 24 kWh pack that weighs 600 lbs, and a lot of other information that is readily available on the web. What I did learn was that the engineers at Nissan have designed the software to allow you to draw down to a 95% depth of discharge (vs. the Volt's 50%). That's pretty gutsy and must mean they are very confident in the battery pack. The pack is composed of 48 Lithium Ion manganese cells. Apparently it's the manganese that tames these cells and prevents them from spontaneously combusting like standard lap top batteries can do. I was also surprised to learn that the battery pack is cooled only by the natural flow of air through the compartment. No fans, no liquid, just wind generated by moving forward, directed into the pack. They said they'd tested it in Tucson during the summer and the batteries were fine. Not unlike what I've found with my LiFePo4 cells.

The second tent was more about sales and painting customer expectations. They touted the cost advantages of driving the car, specifically of electric vs. gas, and they showed off the iPhone app that you can use to keep track of the car. The app is pretty slick. It will tell you all the current status, and even alert you if someone unplugs your car. You can also start the AC system from anywhere; a feature people in Arizona and other hot states will find particularly appealing. While they didn't mention it, I'm sure the same applies to the heating system for colder climates.

The last tent was simply to talk about range and deal with range anxiety. The Leaf comes with Sat-Nav standard and it will paint on the screen circles radiating from your position, that indicate how far you can go. Nifty.

Then it was out to look at the car and drive it. They had the hood open on one and I saw what looked like a valve cover with the Nissan logo. It was actually the top of the inverter, but they said the designed it to look like a valve cover so people would feel more familiar with it.

I met my Nissan co-driver, a pretty young girl named Alex. This was her first day and she knew nothing about the car. Easy enough, it meant I could save my questions for later. I got to drive the Leaf for a grand total of... .3 miles. That's right, around the block. It was slow traffic, but I did get to experience it. I was surprised that when I took my foot off the brake, the car started creeping forward, just like an automatic. Again, Nissan trying to mimic what you're used to and make you comfortable. I never got the car over 25, so I have no idea how it handled at speed. Hell, I never took a corner faster than 5 MPH. I did gun it from a stop at one corner and I was impressed. Just what you'd expect, plenty quick. A tad faster than the Z3.

The brakes took some getting used to. A little pressure and you were slowing down, a little more and you jerked to a stop. I don't quite know how they have the regenerative braking set up, but the scale of pressure applied to the pedal to the amount of regen was not as linear as I would have thought. Over all, the car was remarkable in just how ordinary it was. It's clear that's what Nissan is shooting for. All the benefits of a fully electric car, without scaring people with anything unfamiliar.

Had I not went ahead and built my own, I'd be very tempted to buy a Leaf. For people who want an EV but don't want to build their own, then I'd say go for it. It's just too bad that while the engineers were so hard at work designing the car to be so good and feel "normal" that they couldn't have designed out some of the ugly.

A Good Drive

2010-12-02T11:22:00.000-08:00

Earlier in the week I made plans to go see a friend of mine who lives about 25 miles away in Maricopa. I had planned on taking my gas car, but when my daughter absconded with it, I was left with the Z3. Now, a 50 mile trip shouldn't be a problem for the car, after all it's full range is closer to 60 miles. But this would be the longest trip I've clocked up and most of it would be at freeway speeds. I asked my friend if I could charge up a bit when I arrived and he graciously agreed.

The ride down was pretty uneventful, and I averaged just over 55 mph. At that rate, I watched about 2 amp/hours per mile (320 Watt/hours) click off the Link 10. By the time I arrived, I'd used 52.1 amp/hours for a total of 8.34 kW/hours of the 19.2 available. Some of you may remember that I've got 120 amp/hour CALB cells.

As I rolled into the driveway, the trip meter clicked to 25 miles, we ran the extension cord out and I gratefully plugged in. I set the charger so that it would pull no more than 10 amps. I watched for a minute, no breakers tripped and all was good.

When I went to leave, I saw the charger was off; uh oh. While the breaker never tripped, the power strip that he'd plugged into was not happy with the current and it tripped. I'd managed to pack in 1 full amp/hour before it tripped. Should have checked it. So, with 51.1 amp hours down on the pack I headed for home. "Should be no problem, I've got up to 120 to use," I thought.

Apparently Maricopa is slightly down hill from my house, which now meant I was going back up the hill to Phoenix. I watched as just over 2 amp/hours per mile clicked off the Link 10. I was 95% confident that there would be no problems. I guess you could call that 5% range anxiety (something I gave up on as silly some time ago). For the record, traveling at 55 MPH in 4th gear, the motor turned at about 2800 RPM, and it drew between 2.0 and 2.1 amp/hours per mile, or between 320 and 336 Watt/hours per mile if you prefer.

By the time I rolled up into my driveway, I'd drawn a total of 106.5 amp/hours off the pack. This marked the first time I drew the batteries down below 80% depth of discharge, 88.8% to be precise. There was absolutely no noticeable difference in the way the car drove from when I pulled out of my driveway, apart for the Link 10 blinking at me incessantly that I'd used too much current.

I was curious to see how the batteries measured up after that drive, so I left them to rest for 15 minutes and then took a reading off each cell. The highest cell was at 3.248V, and apart from one cell, the lowest as at 3.231V, but 80% of the cells were at 3.241 + or - 0.003V. The entire pack was at 155.7V vs. 160.0V when it's fully charged.

There was one cell at 3.221V. If I weren't careful, and I ran the pack down too far, that cell is likely the first that would die a horrible death. I'm seeing more and more why bottom balancing the cells is a better strategy than following no strategy, and way better than top balancing. If you're watching amp/hours in and out, not over charging is a snap. But if you're interested in drawing the pack down beyond 80%, you'd be better off making sure all the cells hit bottom at the same time. I need to re-watch some of Mr. Rickard's videos to get details on how to do it.

All in all, it was a great learning experience and I was terrifically impressed with how well the car did. These batteries really are amazing.

A Visitor

2010-11-30T15:09:00.000-08:00

Since I finished the car, I've had a number of people either visit me at my house, or who I've met up with. Each visit has been a lot of fun and I've written about most. Last week, a man from Tucson named Wes stopped by to see the car. We'd been trying to schedule a time to meet for a couple months and our schedules just didn't quite work out. But as it happened, we both had time the day before Thanksgiving.

Wes rolled up in Ford Ranger. He'd purchased the truck a few months back with the intent of converting it to an EV. Who can blame him, it's a good choice. Then he happened across the EV Z3 on the web and thought it was a great idea. He's now reconsidering the Ranger in favor of a Z3. The ranger has a lot of advantages over the Z3: more room for batteries, it can carry more weight, parts are likely cheaper and it has way more room to work with when locating and installing components. But you have to admit, a Z3 is a tad sexier, and I can attest that its way more fun to drive.

Wes and I stood around the car for an hour or so talking about different elements of the construction. He had a lot of good questions and I could see his mind spinning as he was filing it all away. We went out for a ride, and took it on the freeway near my house. Of course the car did just fine, and Wes had an opportunity to see just how fun riding in an EV is. We got back and I shot this picture of Wes next to the car.

I needed a bigger flash. I don't know if Wes will sell the Ranger and pick up a Z3 to do the conversion, but I hope he does. If he does, I hope he figures out better ways to solve some of the problems I encountered. I offered to share anything I'd learned with him, but I think it would be fantastic if he builds one that puts mine to shame. Leave a comment with some encouragement for Wes. How great would it be to have two EV Z3s on the road in Arizona?! Thanks for stopping by Wes.

The Leaf

2010-11-18T20:13:00.000-08:00

Today was the first day I've seen a Nissan Leaf on the road. I was cruising along in the EV Z3 when I saw it approach from the other direction. I recognized it as a Leaf right away, but had second thoughts because I didn't think they'd be available for sale just yet. I figured it must be a Versa, which is the same platform.

But it had that unmistakable trapezoidal door on the front bumper where the charging receptacles are hidden. As it passed I looked back and it had new car plates on it. Sure enough, it was a Leaf. I thought how cools is that, two electric cars passing each other on the busy streets of Phoenix. Of course the driver of the Leaf had no idea there was another electric car anywhere nearby.

I've actually signed up to go test drive a Leaf on December 3rd. I'm really looking forward to it. I'm eager to see how they packaged the whole thing and how well it drives. I'm sure it will be just fine. I really do hope Nissan sells a bunch of these cars. I really hope that every other manufacturer sells thousands of the EVs they're each planning for the future. It's going to be fun to ask the salesman about the car. I hope they have someone there who really knows what he or she is talking about and can give me real data on the car. We shall see. I have no intention of buying one at this time. After all I already own an EV.

As I drove past the Leaf, I couldn't help think to compare the only two EVs in what was very likely a several mile radius. The Leaf was designed from the ground up as an EV and was built by professionals. It's likely to be relatively free of problems and will come with a sweet warranty. It will travel around 100 miles per charge and has A/C.

By comparison, the Z3 was stuck together by some hack in a garage. It has no warranty, and can only go 60 miles on a charge. Plus it currently has no A/C, and won't until that same hack gets off his butt and does something about it. But I ask you. Which one would you rather drive? I knew unequivocally what my answer was as I drove by.

An Interested Individual

2010-11-13T19:53:00.000-08:00

Yesterday, as I was leaving the grocery store, a man walked up to me and asked if the Z3 was a conversion. I told him it was, and he asked if it was a hybrid. I said that no, it was an full electric car, to which he said "Really!?"

What initially caught his eye is that he has a Z3 that is also Helrot (bright red in German) and he noticed the Alternative Fuel plate. He said his first thought was that it was a propane/gas dual fuel vehicle. There are quite a few of those here in AZ (mostly SUVs) due to a botched program sponsored by our state legislature which nearly bankrupted the state. But then he realized it probably wasn't, as there would be no room for a propane tank. Once I told him it was electric, he started asking a lot of great questions.

He asked if he could peek under the hood and I happily opened the car up. He said that he'd had no idea BMW was making electric Z3s. I explained that they weren't, I had made it. He was surprised, as most people are and continued to ask more insightful questions. Every time this happens I like to let that idea sort of sink in; the idea that it was built by just one guy. I really want people to consider the possibility that they too could take on such a project.

I explained how the motor was coupled to the original transmission, a little about the batteries, their capacity and their life expectancy, the cost of the conversion, how far I can drive it and how long it takes to charge. It turns out that he worked in the aircraft industry, and he recognized and appreciated some of the safety designs that I'd incorporated into the car.

When we parted ways, we were both smiling, having enjoyed such a great chance encounter. I understand why a lot of people that convert cars put stickers and labels on the car proclaiming that it's an electric car. It's great to have people ask about it. I love it when people ask about it! But all those stickers and banners aren't for me. I like the clean look of the unadulterated car. I think as more people hear the term "EV" the custom license plate on the car will get a bit more attention. And to that gentleman that stopped me in the parking lot, thanks for asking about the car. I really enjoyed chatting with you.

Car Show Number 2

2010-11-03T20:26:00.000-07:00

Today was the second car show in as many days. Unfortunately, the heat has decided to hang around a bit long here in Phoenix, so while the rest of the country is enjoying the crisp fall weather, it was 92° F and sunny. Too sunny, if you ask me.

Any way, one of our local power companies, SRP, was putting on what they call the "Party for the Planet" event. Apparently this is a yearly event for SRP. They have multiple booths with a wide variety of different groups showcasing their green technologies or methods. One addition they thought would be good was to throw in a few electric cars, so they asked me if would be willing to bring the EV Z3 down. It was a nice turn out of mostly SRP employees.

As it turned out, there were three EVs present. Take a look:

Up front, you can see a Citicar owned by one of the EAA local members named Bruce. Behind that is a Ford Probe owned by SRP employee Abel. Abel told me that the car had originally been owned by SRP and used for electric racing. They sold it away, and he ended up getting some time later from the second owner. It's an AC drive system using Optima yellow top lead acid cells. Eventually Abel wants to drop some lithium cells in it. Behind his car, just peeking around the corner is the little Z3.

Quite a few people stopped by to take a look at it and ask questions.

It was the usual battery of questions, which is just fine. A few people had some insightful questions which is always fun to come across. The nice thing about this show is that there were way more pretty girls stopping by telling me how cute the car was. One girl took some pictures and asked lots of questions that she then forwarded off to her boyfriend who is a BMW enthusiast. I have to tell you, I wonder how BMW enthusiasts would react to this car. I'm not sure if they'd find it really cool, or want to stone me on the spot for perpetrating such sacrilege. She encouraged me to take the car to a dealership thinking that BMW corporate would be very interested in hearing about the car. Perhaps they would. My thought is that it would largely be a waste of time.

At any rate, it was a great day showing off the car, opening peoples minds to the potential of converting a car themselves. It was just too damned hot.

Car Show Number 1

2010-11-02T16:32:00.000-07:00

Just over a month ago, I was able to attend one of the monthly meetings of the Electric Automobile Association hosted by the Phoenix Chapter. It was entertaining and I had the opportunity to meet a few interesting people. One of the people I met was a gentleman named Jim who has been interested in converting a car for some time, and he asked me if I'd be willing to come show the car to him and some of his friends at work. I told him that I'd be happy to do so.

Well, as luck would have it, the company he works for, General Dynamics, decided to put on a car show for it's employees. He invited me to attend that instead, and I agreed, thinking it would be a great way to get the car seen and hopefully inspire a few people. I think all the cars there were actually owned by employees, with one exception; mine.

It started off yesterday with a request to feature the Z3 and one other guy's car in a press release meant to garner some publicity for the event. I consented and gave them a little information about the car. Today, as I pulled up to the check in desk, they knew me right away. I guess word had gotten around, and they all seemed genuinely grateful that I brought the car out. They told me I was going to be parked along side all the "showcase" cars.

I pulled around and parked next to a couple of Cobras, and a slew of 60 muscle cars. I found the whole thing a bit incongruous. Here are all these loud, big, beautiful muscle cars, and then there, in amongst them, almost lost, was my little Z3. I began to wonder how much interest it would garner.

Well, it didn't take long to find out. Before long there was a crowd gathering around the car and people asking the usual questions you'd expect. "How far can you go? How long to charge it? Did you build it yourself? How long did it take you?" Through most of the event there were at least 6 people gathered around smiling, and asking questions. Everyone seemed to have the same opinion; they all thought it was cool.

I confess, I'm not a big muscle car fan. Don't get me wrong, I'm not a green car snob. I love nice powerful, well engineered cars, but I tend to prefer European models. If I could afford it, I'd have an Aston Martin Vantage in one of my garage bays, and a Tesla right next to it. But as the day went on, I noticed something interesting. People stopped to look at the Cobras, the Cudas, the Camaros and the Vettes, but they didn't stay long. Generally there was one or two people around any given car. The little car, that seemed so out of place in the group, oddly enough was the one that drew and kept most of the attention.

It was about 10 minutes after I arrived that I reached into my pocket to get my camera when I realized that I'd left it sitting on my kitchen table. DOH! I desperately wanted to take pictures of the event and of some of the people gathered around the car, but it wasn't to be.

The good thing is that I have another chance tomorrow, at a different car show. One of our local power companies, SRP, is putting on a festival called "Party for the Planet," and they've invited me. I'll be taking the car there tomorrow, answering the same questions I did today, and hopefully remembering to take the camera so I can take a few pictures to share with you.

Back to a Routine

2010-10-30T10:13:00.000-07:00

With the last couple month's posts dedicated to various issues surrounding charging and the batteries, I'm happy to report things have become boring again.

I've already written about the two mistakes I made through this whole thing, hoping that others can learn from my mistakes. First, if you have a charger with the capacity to adjust the current it pushes to the batteries, don't expect that adjusting it up or down will have no influence on the total amount of energy that is ultimately pushed to the pack. Second, a misguided attempt to balance the batteries has done nothing good. In fact it's forced me to sacrifice a small portion of the top of the pack and likely made the bottom more perilous (but I don't intend to find that out).

My goal since all of this began was to find the correct cutoff voltage for the charger. It was a long process, trying different voltages, watching the batteries closely each time. To be honest, it sucked. But during the whole endeavor, I never allowed any of the cells to pass the 3.6 volt cell limit. Ultimately what I found was setting the chargers cutoff voltage for 164.4 volts, at a current of 20 amps seems to do the trick nicely.

The goal has been to charge the pack so that no cell exceeds 3.45 volts. You may recall that originally I was charging to 3.5 volts, but when attempting that now, I found that some cells would occasionally try to head North of 3.6 with a few minutes left on the charger's timer. So, 3.45 seems to be the order of the day.

I've charged the pack some 35 times now and in every case it has gone perfectly. The highest I've seen any cell go was 3.46, and that happened once. Close enough. The difference in capacity seems to be a whopping 1.3 amp/hours, which equates to 3/5's of a mile. I'll just trim off two or three quick launches from stop lights and call it even.

I'll continue monitoring them closely for some time, just to be sure nothing strange happens, and I'll report it if it does. For now though, we're back to a boring, predictable routine of charge, discharge. And I'm quite happy with that.

Charging Mystery Solved

2010-10-21T21:05:00.000-07:00

Well at least I think it's solved. The mystery I'm referring to is why did some of the batteries suddenly start accepting more charge than they should have? My first assumption was that they'd moved in their state of charge relative to the others. But really I had no reason to believe that other than I couldn't think of any other reason.

It was then suggested to me that perhaps those particular cells simply have a lower capacity than the others so they reached their full state of charge first. I think that's likely the case, but truthfully it could be a combination of both reasons for all I know. But that really doesn't answer the fundamental question as to why, when they'd been behaving in a very predictable way for 5 months, did they suddenly start showing the tendency to run away?

Well I think I figured it out today, and I'll explain, but I need to give you some background first. I'd mentioned before that the Manzanita Micro charger has a little potentiometer screw that you use to set the cut off voltage for charging. When the pack reaches that voltage, it switches from constant current to constant voltage and starts ramping down the current according to a timer you set. I'd also mentioned that it can be a finicky thing to set.

Some time at the beginning of August, I was charging the car and I happened to stay in the garage for a while. Normally I charge it at night during off peak hours and I just let it finish on it's own. Well this time I hung around, cleaning up a bit and I saw the charger start flashing, warning that it was overheating. When I set the charger up last February, it was nice and cool in the garage. Not so much in August. To make a long story short, I realized I didn't want to shorten the life of the charger by overheating it every time I charged up, so I decided to turn down the current a bit. Turned up all the way and it sends 28 amps to the batteries. I decided I'd turn it down to 15. Problem solved.

Well, little did I know that I'd just introduced different problem. Apparently the point at which the charger changes from constant current to constant voltage is also dependent on the current out. I now have it set to start it's ramp down when the charger reaches 164.7 volts. But that was set when I was pushing 15 amps. Today was a beautiful cool day, so I decided to give it the full 28 amps and low and behold, the charger switched to constant voltage when the pack hit 163.4 volts, leaving the pack about 3.2 kWh's short of it's full capacity. I stood there for a second thinking "what the hell?"

I started experimenting with different charging schemes and trips around the neighborhood to draw some power from the pack. I left the potentiometer screw alone and just tried different charging currents and I found a curve. Send the batteries less current and the cutoff voltage is higher. Send it higher current and the cutoff voltage dropped. Here's what it looked like:

15 amps = 164.7 cutoff
20 amps = 164.4 cutoff
25 amps = 163.9 cutoff
28 amps = 163.4 cutoff

So back in August I simply dropped the current I was pushing through the charger to keep it from over heating, and the result was that the cut off voltage I had so carefully tuned for 28 amps went up. Suddenly it was too high and ultimately ended up pushing more current to the pack than it should have. I don't know the exact date this happened, so I don't know exactly how many times it happened. I think it's more than 3 but less than 7 times.

But there's a lesson to be learned here. Don't change any thing, be it a setting or a process, and expect everything else to remain the same. Always check and double check when making a change to a procedure or setting. Also, for any of you that have a Manzanita charger, or are thinking of getting one, remember this potential issue. Don't get caught by it. I don't consider this to be a major flaw in the charger, it's minor at worst. But forewarned is forearmed.

On Battery Balancing and Charging

2010-10-13T19:28:00.000-07:00

As I've mentioned in the past, I'm not an expert. On anything. But in the time I've been operating the car and charging it, I've noticed a few things about these LiFePo4 batteries that I think is worth sharing. In addition, think you can draw some simple conclusions from these experiences.

You may remember that just over a month ago I noticed that a few of the batteries were hitting their max voltage before the others. The question became, did those cells move in their state of charge relative to the others, or do the simply have a slightly lower capacity. My assumption right away was that they'd drifted. Quite frankly, it never occurred to me that they might just have a lower capacity, which meant I immediately thought they'd moved relative to the other cells. Of course the first thing I thought to do to fix that was balance them to the others. I drew energy out of the all cells until every cell matched, down to 1/100 of a volt. I drove the car a few miles and then charged up.

That proved to be a complete waste of time. The very same cells that I so carefully matched to the rest exhibited the same behavior the very next time I charged them. This time though, I was watching them. But I'd say this is a clear indication that those cells simply reach their fully charged state before the others. They had not moved relative to the other cells, they just have less capacity. We're talking about a fraction of an amp/hour.

Early on, and for the first month I carefully watched the batteries every time I charged them. I saw very small differences in the finished voltages between the cells; one hundredth of a volt here, 2 hundredths there. And so it went until I had to pull the motor. After the motor was back in, they did the same thing, but I was checking them less often. I guess you could say I got complacent. I went from checking once a week, to letting it go nearly a month. When I did that last check, I found those cells I mentioned running away. There's no question they'd done it before, but there's really no way for me to determine how many times. I know it was less than 20, more than once. I also think there's no question those cells sustained some damaged by it. How much remains to be seen, but I don't think it's substantial.

I think it's likely that those cells were a slightly lower capacity than the others to start with, so they filled up first. In that 20 or so charges, they'd reach their 3.6V maximum and be forced a little higher. Each time, just a little further. In this way they accrued a little more damage each time. Had I watched them more carefully, I would have caught it. But, it is what it is, and lesson learned. Since I rarely pull more than 50% capacity from these batteries, I don't think I'll ever really feel the impact of that. Perhaps I'll get only 2900 cycles out of those cells instead of 3000.

But all of this got me thinking about battery management systems. I don't mean to imply I never thought of them before. I have, a lot. But, the ones on the market shunt off power in the form of heat when a cell reaches capacity. I can't stress enough how much I don't want that anywhere near my car. Maybe that extra heat is OK when you're in Minnesota. It's not in Arizona. No extra heat is acceptable as far as I'm concerned. I'd rather ruin a set of batteries than burn my house down.

I believe what would be ideal is a charging/battery monitoring system that has the capability of charging cells individually. A monitor on each cell would watch the cell, and when it reached it's determined state of charge, the monitor would simply shut the charging for that cell off. Not shunt the power away, but rather throw a relay that would simply stop power flowing to that cell. Of course it would need to send signal back to the charger so the charger would know that one less battery was accepting a charge. The charger would then ramp down the current it's putting out by the corresponding amount that the deactivated cell had been drawing. Otherwise, you'd have a cascade failure as more cells dropped off line, the current traveling to the remaining cells would climb until you started burning wires.

This strikes me as spectacularly complex. Doable, but due to the complexity, likely very expensive. Not only that, but complicated which means an increase in the likelihood of failure. You could certainly design the system so that failures resulted in a system shutdown, not a runaway charger. But could such a system be designed? I think so. The net result is batteries charged to the same voltage every time. This of course would be a top balanced pack. Jack Rickard has done quite a bit of work and demonstrated the dangers of top balancing. So the only way this is practical is if you simply hold the bottom 5% of the batteries state of charge as off limits. Meaning you could never run the batteries close to depleted for fear of having a cell reverse it's self.

The next best option would be similar but much more simple. A similar system with a monitor on each cell. It watches the voltage for one cell. When any cell reaches the target charge state, it sends a message to a main board that in turn trips a relay that cuts power to the charger. Sure the batteries might be at slightly different states of charge, but who cares. No battery is ever endangered and your pack is charged. The advantage to this is that you could, if you chose, bottom balance you're pack with this set up. Once balanced the charger would cut off as soon as the first battery reached it's limit and there would be no effort to move the others any further, keeping the batteries in the same positions relative to each other.

It seems to me that this would be a far simpler solution to charging and protecting your batteries and far safer than creating heat in a confined space but shunting off lots of power. I would consider putting that in my car. Heck I'd design it and build it myself if I were talented enough.

When it all comes down to it, I think my problem was one of charger set up. Setting the charger and thinking once it was tuned in nothing would change was clearly a mistake. Like I said, lesson learned.

One More Thing

Today I met with a gentleman named Alex who has been following the EV Z3 blog and the progress with the car since just before it hit the road. Alex is traveling at the moment and had a stop over here in Arizona, so we decided to take the opportunity to meet up. We had a great time. We took the car through down town Chandler, (which is unfortunately under construction) and out on the freeway. People often ask whether it can reach freeway speeds, so I thought it would be a good idea to show Alex just how well it does.

He's been considering doing a conversion of his own for a while, although his ideal car to convert is a Porsche 911. How great would that be?! Hopefully the Z3 helped to inspire him to tackle the project some day. Keep in touch Alex, and if you decide to tackle that Porsche, let me know so that I can follow the blog on your build. You will keep a blog, right? :) Thanks again!

The Charger Has Returned Home

2010-10-07T20:23:00.001-07:00

The charger arrived back from Manzanita Micro today, safe, sound and in perfect working order. They received it last Thursday, and had it fixed and on it's way back to me by Monday. I found out that it was the AC rectifier bridge that I'd damaged. They repaired that and then fully tested the unit to make sure it was healthy in all respects. The grand total in charges... $125, and $50 of that was shipping. How great is that!? I seriously hope I never have to send it back, but if I do, I know it's in great hands.

I got it back and began re-assembling the car. I hadn't done too much to it, so it only took me an hour or so. It was with some trepidation that I threw the switch to start charging the car. But it turned out my concerns were not needed. It fired up and started working like a dream.

I would still like to install the inrush limiters, or thermistors on the DC to DC converters. I bought a little project box, meaning to do it during this week's down time. But I found out more about they way they work which forced me to change my plans. When cold, they offer high resistance to the current, which keeps the arcing to a minimum, but they quickly heat up as current flows through them and the resistance drops. It's not unusual for them to reach 200° F. Well the project box I bought was plastic, so that wouldn't do. But worse, the only place I have to mount them is against the plastic box in the trunk that holds the charger and DC to DC converters.

So, I need to re-think how I'm going to do that, and where I'm going to mount them. I'm kind of at a loss right now, but I'll figure something out eventually. I could disassemble the DC to DC converters and actually put them inside the housing, but I really don't want to do that. Regardless, tomorrow I'm back on the road with a nice big EV grin!

COMPLETELY OFF TOPIC

A friend of mine named Fred and I have launched a new blog. It is called F1-Geeks, and as you might have guessed, it's devoted to Formula 1. But that's not all! We actually intend to talk about several topics that we and others like us find particularly interesting; cars, gaming, tech gadgets, home theater stuff and EV stuff too. Check it out, and leave us a comment or two if you feel like it. Thanks!

Insulation

2010-09-29T15:32:00.000-07:00

Here we have a nice shot of the damage caused to the terminal when my meter's probe slipped off the top of the nut and shorted against the base of the terminal and that aluminum angle piece to the right.

Clearly, I couldn't leave it like that. Being as clumsy as I am, it's bound to happen again as long as that aluminum perches so dangerously close to those terminals. I can't move the angle aluminum because it's what's holding the batteries in the car. I figured the best thing to do was to put some sort of rubber insulation on the aluminum to keep any accidental shorts from occurring. So, I went down to the local hardware store to look for a sheet of rubber. What I ended up finding was a sheet of PVC used for lining the floor under a shower pan. Waterproof, flexible, and more importantly, electrically non-conductive. It's sold by the linear foot, and one foot of the stuff cost me less than $6.

I cut a few carefully measured strips from the sheet and painted some contact adhesive on one side.

I masked off the angle aluminum as best I could and painted those with the adhesive as well. After a couple hours of drying time I carefully stuck the strips to the aluminum.

It stuck on very well and should do the job. I had cut the strips so that I could wrap them around the bend, hoping that the sheet would stick to the inside edge's 1/8" surface of the aluminum. But the material simply isn't flexible enough to make that bend. If I could find a sheet of real rubber, and if it were thin enough, it would make that bend, but I think this will work fine. Take a look, there's no way to short the terminals against those aluminum pieces by accident.

Chargers Away

2010-09-27T15:43:00.000-07:00

One of the tough things about building this car was the extremely tight spaces I had to work with and in. Getting my arms back there to turn the screws and bolts that held the charger in was so difficult. It took me the better part of an hour, but I finally liberated the charger from it's home.

Here's the charger, which looks totally fine.

I packaged it up very carefully and handed it to UPS this afternoon. In an email exchange with Rich from Manzanita, he said that assuming nothing other than the input AC rectifier is damaged, they should be able to fix it up in a day or two for around $200. How great is that?!

As I've mentioned before, I need to raise the height of the front of the car. I found a place that will build new springs for me, but they want one of the springs and some measurements off of the front suspension. Well, I can't take a spring off the car and mail it away, I'm using them at the moment. While looking around on eBay for a spare spring I can send off to Kansas, I came across an item that I had always felt sure must have existed, but I'd never seen. A quick search in Google and I found these items.

These are spacers that you can slip between the coils of a spring to give it up to a 1" lift. The springs on the Z3 were already riding low when I bought the car. The car was riding about 3/4" lower than stock. With the extra weight of the batteries and motor, it dropped another 3/4".

I took a look at the springs and the bottom 2 coils were very close to each other. I jacked the car up one side at a time and slipped them in, wedging them as far down in the coil as I could. I sat the car back down, drove it around a bit and then measured the ride height. It gained 2cm, or .79". That's more than I lost from doing the conversion. It looks much better too.

Of course that means I've lost a bit of spring travel, but not 2 cm since the gap I squeezed the rubber piece into was more like 1 cm high when the car was on the ground. The real question is will that loss of 1 cm of spring travel cause me problems. I don't think it will, I already drive it very carefully and slowly over bumps. But it's the bumps you don't see that get you. The good thing is that if the spring should collapse all the way, that big grommet is rubber and will flex. Hopefully enough to protect the pillar.

I think it's a good band-aid solution, but I'm going to continue my efforts to get the car sprung properly.

Something Stupid

2010-09-23T07:50:00.000-07:00

Just when everything is going well...

I've been making slow progress zeroing in on getting the charger set to bring the batteries up to the optimal charge point before it turns off. It's tough because the charger uses a little screw potentiometer to adjust it up and down. It's exceedingly difficult to get it right where you want it. Plus I've found that if you change the current you're pushing to the pack, the high voltage point at which the charger believes it's done changes.

When I have the charger turned up all the way so that it's pushing 28 amps, it would cut off at 164.5 volts. But if I ramp the current down to 10 amps, it trips off at 165.8 volts. It would be so much nicer if the charger had a digital interface for setting the cut off voltage. I realize that would add to the cost of the charger, but I have to tell you, I'd pay for it.

This morning I was charging the car at 10 amps The charger hit it's limit threshold at 164.7, which is about where I want it. I started taking measurements on the cells to monitor how they were doing. There are a couple that come up to 3.6 volts faster than the others. While measuring one of the cells I slipped and touched the probe to the chassis while it was on the positive terminal for that cell. Well, there was a loud pop, and a nice bright flash. When I looked down, the point on the end of my probe had been melted to a nice rounded blob, the terminal had a big black spot around it, and the charger had flipped off.

I checked everything and couldn't find any obvious problems to any of the systems. I tried to turn the charger back on, but there was no power to the charger; the breaker for the outlet had popped too. I reset it and tried to turn the charger on again. Loud pop, but no flash anywhere, and the charger tripped it's breaker and the breaker on the house tripped too. *Sigh*

So it would seem that through clumsiness or carelessness, I've damaged my charger. I've sent an email off to Rich Rudman at Manzanita Micro to get his advice. But I'm pretty sure that the chargers coming out of the car soon and making a trip to Washington. Man I hate it when I do stupid stuff. And just as the weather is really getting beautiful for top down driving! *Sigh*

UPDATE:

I heard back from Rich at Manzanita. Apparently I've blown the input AC rectifier. So, I'll be taking the charger out of the car ASAP and sending it back to them for repair.

More Battery Info

2010-09-17T09:30:00.000-07:00

I've spent the last week and a half working with the batteries and charger, trying to fine tune and develop a charging plan. The more I've worked on this, the more I'm starting to think the problems I've encountered up to this point were simply a result of setting charger's cutoff voltage too high.

Initially I'd set it at 168 volts, because that's the target voltage I wanted (3.5 x 48). But of course, that was too high because the charger simply begins it's ramp down of current at that level. That lasted one charge, then I turned it down to 166.5. That worked out well as the voltage on the pack was at 168 when the charger finally cut off.

But clearly as the cells broke in, or started showing their individuality, some started reaching their target voltage before others. In terms of actual current pushed to the cell, the differences are so small. In the last post, I'd figured that the difference between the extremes was about 7.3 Watt hours. That may actually be a bit high. It may be closer to 5 Watt hours.

I lowered the chargers cutoff to 165 volts, and that seemed to be working quite well. That put the finishing voltage at around 166.8 volts. The batteries prone to runaway were hitting about 3.58 volts, by the time the charger kicked off. The rest of the cells were only just behind. The difference in the entire pack's charge state reduced by only 150 Watt hours or so. But on two occasions, I saw one of the cells climb to 3.60 volts when there was around a minute left on the charging cycle. Had I let it go, they would have climbed to somewhere close to 3.64 Clearly, I needed to back it off just a bit more.

This morning, I charged the pack with the charger starting it's ramp down at 164.5 volts. It finished at 166.3 volts, with the highest cell at 3.52 volts and the lowest at 3.43. That, I think, will be just fine if we get something like that each time. I'll continue monitoring over the next few weeks to see how things progress, but it's looking good at the moment. As best I can figure, that cost me another 100 Watt hours. So I'm down my a grand total of 250 Watt hours in the pack. Less than one mile.

Springs

I had a local shop look at the springs on the car Tuesday. Since the car was riding 3/4" lower than stock when I got it, I had always wondered if it had received aftermarket springs to lower it, or if the original springs were just tired. They invited me down to take a look. Turns out they are the originals, which means I have two options. I could get coil overs for around $1500. Or I could have some springs made. A place out of Kansas City will fabricate new springs for me which will take the proper weight, if I send them one of my springs, some geometry measurements off the suspension, the new weight of the car and $285. Sounds like a good deal to me, but I'm not in a position to take a spring off my car. I need to find one at a local salvage yard. Over all the car is riding 1.5" lower than stock, but just on the front end. The back end is perfect. I look like I'm going down hill all the time.

Plates

The good people at ADOT have seen fit to grant my request for a custom license plate. Check it out!

How sweet is that?!

First Charge After Balancing

2010-09-09T06:41:00.000-07:00

Yesterday I drew off about 5 kWhs from the battery pack while driving the car around. This was after I had balanced it the day before. So I was all set to charge the pack to find out how the cells behave.

Before I get to that though, I had been in contact with Jack Rickard letting him know of the imbalance in the pack. Jack is the champion of the "No BMS necessary" movement. He warned me of dangers involved in "top balancing" the pack. For those of you unaware, the concept here is that there is far more danger involved in having the state of the cells differ while down at the bottom of the charge curve, than while at the top. The danger being that if one cell drops below the 2.0 voltage limit, the others will drive it into death very quickly.

I believe this to be a real threat, Jack's tests have demonstrated this. But for the moment, I'm not worried about cell behavior at the bottom of the curve as I'm not taking them there. I am worried about what they're doing at the top because that's where I'm seeing the discrepancy. But it looks like that concern may be misplaced.

When I charged the pack last night, I watched as all the batteries marched up the voltage curve in nice even step. They all arrived at 3.38 volts together. But then a few of them hit 3.39 while others lagged behind. There was one cell in particular that started climbing faster than the rest. When that cell hit 3.50 volts, the others were around 3.44, plus or minus .02 volts. I watched carefully until that one cell hit 3.60 and I killed the charger. By that time the others were around 3.49 volts.

So now I think I know what's happening. I have my charger set to cut off when the pack reaches 165 volts. Or rather, it starts ramping down the current when it gets there. The idea being that it stops charging when the pack is at 168 volts. That would put each cell at 3.5 volts. Early on I had made the assumption that the cells that were coming up too fast had shifted in the pack, that their state of charge had moved relative to the others. I don't think this was the case.

Jack had pointed out that another possibility is these cells have developed a diminished capacity. Well, I think that is the likely explanation as sad as that is. Think of the batteries as if they were a jar you poured fluid in. If one jar in the mix suddenly has a little less capacity (you've dropped a rock in it) when you're adding water to them all evenly, one will start to overflow before the others. What is clear is that it wasn't a result of cell drift within the pack because balancing them would have resolved the difference. The question at this point is how much has this rogue cell lost?

Keeping in mind the characteristics of these cells to runaway very quickly at the top and bottom of the charge curve, what I need to do is figure out how much more time would be required to fill the rest of the batteries after this one was charged completely. Based on what I was seeing during that last charge, I'd place that at about 5 minutes. I know that each cell has 408 Watt hours (120 Ah x 3.4 volts). During charging, each cell gets 1.46 Watts per minute. So if this cell is full 5 minutes before the others, that means it's capacity is 7.3 Watt hours below the others, or 1.8%. It also means that if I cut off the charger when that cell has reached it's peak, the rest are missing out on that 5 minutes of charging, which translates into 350 Watt hours, or one mile of travel (at this time).

To the best of my knowledge, all this is correct; however, I'm not above making boneheaded mistakes, as anyone who reads this blog can attest to. But all of this raises a few questions. The most obvious is would a BMS help the situation. I think it would, but there are trade offs I'm not comfortable with. The first being the cost. The second being the fact that the extra power to the cells which reach their capacity first is simply shunted off as heat. No thanks, it's already 110 °F in my garage. There's no way I'm risking setting my car on fire. To me, that negates all the benefits that come with the slight reduction in worry to the health of the pack.

Besides, at this point, what's it going to gain me? It would seem one mile. If I wanted to be extra sure I'm not endangering the pack, I could dial the charger back a bit more, reduce my range by say 5 miles and really ensure there's no risk to the pack! I've got 60 miles to play with, what's 5? Nope, still not seeing a compelling reason to add a BMS.

The other question is would it be worth going through the process of bottom balancing the pack? I'm not entirely sure what it would gain me at this point. It would make longer trips safer for the batteries as they'd all meet their discharge point at the same time. But I never really drive the car more than 40 miles at a time, usually only 25. That's something I'll reserve for some future time.

For now, I need to fine tune my charger to be sure and protect that cell. The others that weren't far behind it in voltage during last Friday's charge are presumably in the same boat, but not as bad. It stands to reason, if I charge the pack being sure to protect that cell from over charge, the rest are safe. Still, I'm going to have to watch them all for any further deviation.

Battery Balance

2010-09-07T09:20:00.000-07:00

I'd hoped this day wouldn't come, and that this problem wouldn't occur, but it has. I was charging the batteries last Friday and I found a couple of them heading North of the target 3.5 Volts. CALB (the manufacturer of these cells) recommends that you charge them to no higher than 3.6 volts. You can imagine my concern when I found 4 of them higher than 3.8! Well, that just won't do, and if that continues, I'll shorten the life expectancy of these rather expensive batteries.

Now, I know what some of you are saying. "Of course you idiot, you're not using a BMS. You must use a BMS with these cells, what did you expect!?" To you folks I say you're right. Sort of.

There is no question that these, and in fact all batteries need battery management of some sort. The conventional wisdom regarding LiFePo4 cells is that you must use an automated BMS to protect them from overcharging. But, keep in mind that even lead acid batteries need BMS. The primary difference being that people tend to manage lead acid batteries manually, watering them and equalizing them on occasion. As I see it, the real question is whether you need an expensive automated BMS system for these LiFePo4 cells, or can you manage them yourself like you would lead acid batteries?

So far these batteries have been really boring. They've all charged up to 3.5 volts reliably and stayed in balance nicely. Keep in mind that after you remove the charger current and let the cells settle, they end up around 3.4 Volts. Their stability had lulled me into complacency and I hadn't checked the individual cells while charging for a month or so. In that time, a few of them drifted. I don't know why; the heat in the garage, bad connections, differences within the cells themselves? Chances are I'll never know, and in all likelihood they'll do it again.

Right now I'm equalizing them, getting each battery down to 3.350 Volts. This is a long, boring procedure, but not particularly difficult. I've simply hooked a 12 volt brake light to some alligator clamps. I clamp the meter to the posts and then the bulb. The bulb glows and burns off the extra electricity. It's just a question of stepping through each cell. About half are at the right voltage already. The rest are within 0.05 Volts, except the 4 naughty ones that were at 3.6 after resting, or .25 Volts too high. Like I said, not difficult, just boring. You must pay close attention.

Now the question becomes how often am I going to have to do this. Lets assume that it's in their very nature for the batteries to do this. Then how often will they drift? What's the rate of drift? Can I expect them to fall out of balance on the very first charge, or will it take 6 months? Will it be a gradual change, or will it happen within one charging session? The answer to these questions really determines the risk that the batteries face and whether I'm going to need to give in and get a BMS.

If the past 7 months can be used as a baseline, I'm thinking that I may be able to go 4 months before I need to worry about balancing them. Remember there was about 2 months of down time when I had to remove the motor. If I really can wait 4 months before I need to take action, then I'd say a BMS is not necessary. However, if I charge them up tomorrow and see some of the cells immediately going higher than 3.5 volts, that likely means that the only way to prevent that is a BMS system. If the mean time to imbalance (mti, for all us geeks who live in a world of three letter acronyms) is somewhere in between those two figures, then it just becomes a question of weighing the inconvenience involved in manually balancing them, and how often I have to do it. Not to mention whether I'm willing to endure the pain of having to regularly measure the cells close to the end of a charging cycle.

One thing is certain, and that is I'm going to have to monitor them very closely over the next several months to get a clear idea of what's happening and when. In either case, I intend to protect these cells from that kind of event again. Along the way, I'll record what I'm seeing here. Those of you who care to follow along may learn a thing or two about the cells and how they behave. I may find a BMS is essential. Or I may find that with a little care, you can do just fine without one. Apart from the fact that I'd rather not spend somewhere around $3,000 for a BMS, I have no passion for one position over the other.

Getting Some Driving Time

2010-08-18T08:45:00.000-07:00

The heat here in Phoenix is letting up a bit. Not enough to comfortably drive the car in the middle of the day, but early and mid-mornings have been very nice. Every morning I take the car out for a daily errand, and it's just fabulous. What a great car to drive!

Back before I had to remove the motor, I was giving a friend a ride around the neighborhood to show him the car. I drove by a neighbor that lives around the corner, he and his daughter were in the street playing catch. As we approached, I was worried they might not know we were coming, but they saw us and moved aside and we all waved as we went by.

When we came back by, I slowed down to be sure we were all safe, and the father called out "Is that an electric car?" I told him it was, and he said that he knew it had to be because it hadn't made any noise when we first drove by. I stopped for a few minutes to chat. He had a lot of questions about the car, and seemed truly interested. I answered them all as best I could and waved goodbye.

Over the past few days, since I've been driving it more, I've happened by him a few more times. Each time he eagerly waves and smiles. It's great to have made a connection with a neighbor, I hope to talk to him more and maybe offer a ride someday. But the best thing is that he's seeing an electric car driving around the neighborhood on a regular basis, and he has a positive attitude about it. I hope that it's situations like this that will slowly help to convince more and more people that an electric car IS a viable option for some.

I'm still averaging about 325 Watt/hours per mile, which isn't horrible, but I'm pretty sure that will get better with the modifications I've planned for this fall. New springs in the front, fix the alignment and replace the differential's fluid are what I have in store as soon as the weather really starts cooling off.

There is one small thing that's been driving me crazy, and that is a rattle coming from the rear of the car. A rattle whose source, I've not been able to locate. It only happens when I'm heading over bumps, so at least it's not constant. I've looked for it repeatedly, driving the car up on the ramps and poking and prodding, but with no luck. It has a real tinny sound, so it's something small, and I thought I knew exactly what it was. It sounds like one of the clamps used to compress the batteries in the rear battery box is loose. But I've checked them all, and they are all nice and tight.

It's definitely coming from the back end though. The funny thing is, no one else notices it until I point it out. Then they all say something like "It's not that bad." They're right, it isn't, but it drives me nuts. I'm going to have to drive up the ramps again and really give the back end a thorough inspection. I'm not worried that anything is going to fall off or come undone. I used self locking nuts on all the connections in the car; the kind that can't spin off on their own. Eventually I'll find it. I just hope it's before I go mad.

I'm going out to the Diamondbacks baseball game tonight with a friend. I'd love to drive the car there, but the heat would make that an unpleasant drive. The real sad thing is that the ball park has removed their electric car parking spaces! They had 2 spaces in one of the closest parking structures, right up front, with charging stations and everything. I called to find out if they were still there and what was involved in using them, only to be told that they'd been removed. Sadly, the last time I went there, I found they had indeed been turned into handicapped spaces. *Sigh* I can't really blame them, they were empty every game, but what lousy timing!

Interesting Results

2010-08-10T10:17:00.000-07:00

Over the weekend, I ran the final test (for now) on the high voltage system. I hooked up the last piece of equipment to be tested, the DC to DC converters, and let the car sit for 3 days. By the end of the three days, the Link-10 showed that 2.18 kW-hs had been drawn off the pack. For those of you keeping track, you'll recognize that number as being very close to what we've seen in the past. Indeed, previous tests have all come up showing 2.15 kW-hs over the same time period. I'd mentioned that I expected this test to be a bit different because the fans for the DC to DC converters run continuously due to the ambient air temperature. So, at first glance it looks like we're seeing that difference. The interesting thing is what happened when I charge the pack.

On prior tests, the meter showed that the pack had lost 2.15 kW-hs, only to find when I charged the pack it would only accept around 200 W-hs. When I've worked out the math each time, I found that the Link-10 was introducing a about a 700 W-h per day error. If you want to be precise, it's actually 650 W-hs, but I rounded up 700 because it's easier for me to remember and for a few other reasons that would simply put you to sleep if I enumerated them.

Anyway, this time proved to be a bit different. I plugged in the car, started up the charger and stood there waiting for the charger to indicate it was done. I figured it would take 5, 10 minutes max. Well, after waiting for 15 minutes, and watching over a 1 kW-h be pushed to the pack, I realized that this wasn't going the way I'd expected. By the time the charger finally kicked off, it had pushed a total of 1.53 kW-hs into the battery.

Even though the Link-10 showed nearly the same draw over the 3 day test as it did on every other test, there had actually been a real draw off the pack that amounted to 511 W-hs per day! I'll talk about what the real power draw means to me and the car in a moment, but for now lets talk about the meter. The only problem is that I'm not so sure I can put it into words.

Essentially what we see is the meter failing to register the draw off the pack. Arguably, and presumably, if you increased the draw up to that magic 700 W-h per day error that seems to be inherent in the meter, the meter's reading wouldn't change much. For now, we can only speculate that would be true. What would be interesting to see would be if you increased the real draw on the batteries up to 800 W-hs per day. Would the meter begin to register that and show the real number? It's interesting to speculate, but I have no idea for now.

So what does the 511 W-hs per day that the DC to DC converters draw mean to me and the car? First, I'd like to know how much of that we can attribute to the fans. I can't easily get to the fans to see what their labels say with regards to power draw, but they seem to be ordinary 80 mm 12 VDC computer fans. One that I have laying around here says it uses .075 amps at 12 VDC. If we use those numbers (which are close enough for now), keeping in mind we have two fans, that comes out to a total of 43 W-hs per day. That seems like a pretty small fraction of the 511 W-hs that is actually being consumed. I can only assume that the remaining 468 W-hs is being gobbled up by the DC to DC converters as some sort of offering to the gods of inefficiency in the form of heat.

I think what that means is that it really would be worth while to look at turning the DC to DC converters off when the car is off. You may remember that I looked into that a couple months ago, installing a couple relays to turn the converters off when the car was off, and I ended up welding the relays shut. I contacted Ryan Bohm at EV Source and told him my dilemma. He recommended an "inrush limiter" for each of the converters. I ordered them and have them here. They really should be installed in the unit itself. Only downside there is that I have to take the converters out of the car to do so. Another task to add to the list of things to do. Mean while, the car still runs great and remains fun to drive.

A Quick Recap and A Few New Objectives

2010-08-06T11:06:00.000-07:00

We're back from vacation and feeling great. Northern Arizona is beautiful country.

For those of you following along, you know I've been trying to sort out some apparent drain on the high voltage battery pack when the car is off. To do so, I've decided to test each, individual component, adding them one at a time to the system to see if I could determine the culprit.

What I was seeing, before the motor problems, was that when the car was sitting in the garage, off (or anywhere else for that matter), the Link-10 meter would report that approximately 1 kWh per day was being drawn off the pack. Through careful testing, I've discovered that the Link-10 is responsible for about 700 W/hours of that. That leaves about 300 W/hours yet to find. I say "about" because I didn't track the drain that carefully. It's just my recollection that it was about 1 kWh.

Anyway I've tested all the components, except for one, and found each draws no measurable power from the pack. Even the Link-10. It reports 700 W/hours per day, but it doesn't really use anywhere close to that. The only thing left to check is the DC to DC converters. Well, until summer ends, and the thermostat in the converters is happier with the air temperature, any test is not going to duplicate what I saw back in February and March. But I guess that's not entirely bad.

I've decided I'll go ahead and run the test with the DC to DC converters hooked up and running, even though the cooling fans will be spinning constantly the whole time. I'll still get some data, and it could be useful. I'll keep you posted on that.

By-in-large though, I think I've got most of what I was looking for. I know that the apparent draw off the battery pack, when the car is off, is a phantom. It doesn't exist. I wish the inaccuracy weren't there, but it is.

Now, there are still a few things that I need to do to the car. Some more important than others. I thought I'd share them with you now.

Get the front end ride height adjusted.
Get the front end aligned to remove any toe-in.
Replace the differential fluid with Red Line (I did the transmission during the main build).
Add an expansion chamber for the Zilla's coolant. You read that right. I didn't put one in when I was building the car. I realize now that wasn't the smartest thing, so feel free to mock me.
Fit and adjust the v-belt for the compressor.
Remove the AC lines and have them redone.
Install a rubber membrane to the underside of the hood (bonnet, for my European friends) to keep the battery terminals off the steel in case of an accident. Let's hope that turns out to be a complete waste of time.

That's about all I can think of right now. You may have noticed that most of this list would require working on the car. In a garage. Well, it's 110 °F in my garage. It's going to take some time to convince myself to get out there and get going.

Getting Closer

2010-07-27T15:24:00.000-07:00

This weekend's test with the Zilla attached proved to be as uninteresting as I had anticipated. The Zilla supposedly only draws 30 milliamps. What I found supports that. After three days with the Link-10, heater, charger, and finally the Zilla attached, the meter reported that 2.15 kWh's had been drained from the batteries. No different than any of the previous tests.

That leaves only the DC to DC converters left to test. As I've reported before, the ambient temperature here in Phoenix is high enough that the cooling fans on the converters run non-stop. I don't see any point in testing how much that draws off the pack. I'm far more interested in what is drawing power off the pack when the car appears to be doing absolutely nothing. But from the looks of things, that won't be the case until September some time.

For now I know that at least 700 of the Watt hours per day that the meter reports having left the pack is fictitious. I can live with that for now. I still have some other issues to deal with, which are minor in nature, but some of you may find interesting. Right now, I'm in lovely Sedona, so those will have to wait for next week.

Testing: Stranger Still

2010-07-23T10:15:00.000-07:00

I've been trying to determine which component is responsible for leeching power from the high voltage system when the car is idle. So far I've found that the Link-10 meter will unfailingly show a 700 Watt/hour per day loss, which I've determined to be largely inaccurate. I've run the same test with the ceramic heater hooked to the system (mind you it was off, just like the rest of the car) and it added nothing to the reported draw off the pack.

I finished a three day test yesterday in which I'd added the Manzanita Micro charger into the mix. At the end of the three day test I looked at meter, and what I found didn't surprise me at all. The meter read that there had been 2.15 kWhs drawn from the pack. That lines up exactly with what I would have expected, and so I can infer that the charger didn't draw any additional energy from the batteries. Again, not to surprising, but I have to test everything if I'm going to be thorough.

What was surprising is what happened when I charged the pack. In the first two tests, I saw that 2.15 kWhs had been drawn off the pack (according to the Link-10). But when I charged it, the charger read the pack as fully charged within minutes and when it finally shut off, it had only added 200 Watt/hours to the pack. So really, there was only 65 Watt/hours per day that were actually consumed. The first two tests had nearly identical numbers. Well, when I charged the batteries this time, the charger said the battery pack reached it's target voltage while I was turning the dial up to increase the current. When it finally kicked off, it had replaced a mere 60 Watt/hours. So, in this test, with only the Link-10, ceramic heater, and charger hooked to the high voltage system, their combined draw was 20 Watt/hours per day.

How could there be such a discrepancy? And how could the three components combined draw less energy than two of them? I think the answer is they didn't really. In spite of the fact that I'm trying to run these tests in the most controlled manner possible, I'm limited by the quality of the equipment. After all, it's not high dollar lab equipment, they're EV components. There is some inaccuracies inherent in each, i.e. the consistent 700 Watt/hour per day error in the Link-10. In this situation, I think we've exposed another inaccuracy in a different component, the charger.

The Manzanita Micro charger is fantastic as a bulk battery charger, and I think it does a terrific job. It is not a high dollar piece of bench lab testing equipment. It uses a potentiometer adjustment, made by the user, to determine the cutoff voltage for charging. I've set it such that the charger starts it's ramp down when the battery pack gets to ~165 VDC. It then ramps up to ~168 VDC before the timer runs out and it turns off completely. Now, the reason I use a "~ " is because it is it's all relatively approximate. Sometimes the timer comes on at 165 VDC, sometimes it comes on at 165.5 VDC. In addition, you may remember I'd said the algorithm it uses for how to ramp the current down is a complete and total mystery. So sometimes it will dump an additional 150 Watt/hours into the pack after the timer starts and sometimes (apparently) as little as 20 Watt/hours.

I guess the short of it is that using the charger as an instrument for doing the fine measurements I'd like to employ on this test is silly. At best I think I can only hope to get an idea of what's drawing current off the pack when the car is off. I've already discovered that the meter is responsible for most of what I've seen simply due to the error inherent within the meter. Am I going to find where that remaining 300 Watt/hours per day are going? I'm not sure, but I'm going to keep trying, and my feeling is that I'll find the DC to DC converters are drawing some of that current.

In any case, the next component to check is the Zilla controller. How much does it draw? Well it's supposed to be just a few milliamps. Over a 24 hour period, I'd be surprised if that registers on the meter. But I intend to test it anyway. That test began 30 minutes ago.

Stay tuned for the increasingly irrelevant conclusion!

Testing Continued

2010-07-19T15:01:00.000-07:00

Before I talk about the results of the most recent tests, I thought everyone might enjoy seeing one of the shots I took of the car, which I sent off for the book the EV Z3 is going to be in. Behold:

Considering the day was a bit cloudy and I don't own any lighting equipment other than a camera mounted flash, which I didn't use, I thought this turned out pretty good. Say what you want about the conversion, but it is a pretty car.

Anyway, back to the test results. So, over the weekend, I left the car idle, in the garage with only the following items attached to the high voltage side: the Link-10 meter, and the ceramic heater. As I mentioned in the last post, there is really no way for the heater to draw any current, but I swore I'd do more thorough tests, and that's what I intend to do. In fact, I decided against the idea of cutting that test short because I didn't expect the addition of the ceramic heater to amount to any difference. After all, if you allow your expectations to influence the method of your testing, your expectations influence and then determine the results of your test.

What did I find, you ask? Pretty much what I expected. The addition of the heater didn't change results at all. Over the time frame, the meter showed that 2.15 kWhs had been consumed. That is bang on what it said when I had only the meter attached. But if you remember back to that test, when I charged the batteries, they only accepted 200 Watt/hours. And after all, that's really what I need to know; how much energy was actually drawn out of the pack. This time was no different. About 3 minutes after I turned on the charger, the battery pack reached it's peak charging voltage and the charger began to ramp down.

By the time it had finished, 220 Watt/hours had been pushed back into the pack. I'm not concerned with that extra 20 Watt/hours that showed up in this test versus the first test. If I did the same test 10 times I'd expect 10 slightly different results because the charger introduces some randomness to the equation. The algorithm it uses to determine how many amps to push out while it ramps back down to zero during the cool down phase is anything but predictable. A 10% difference at this level is not a big deal. Considering the 2.15 kWhs the meter originally stated had been drawn off the pack, that 20 Watt/hours is only about 1%.

On the surface it would appear that I didn't learn anything. But really I did learn that the ceramic heater is definitely not drawing any current when it's off. It's true I expected that, but I also learned that the Link-10 showed the same error in metering 2 tests in a row.

In order to charge the battery pack I had to hook up the charger. That means that right now the Link-10, the ceramic heater and the charger are the only things hooked to the high voltage side. That sounds like a perfect recipe for the next test, which commenced 30 minutes ago.

Not Much to Report

2010-07-16T08:29:00.000-07:00

Everything has been running smoothly this past week. The few times I took the car out, it hummed along effortlessly, with no hint of a problem. For those of you not following Arizona's weather closely, it's been hot. Hotter than usual. Yesterday was 116 °F with humidity near 50%. There was no way I was taking the car out in that weather. Remember, no AC.

I'm continuing my tests this weekend to see if I can find which component is leeching power from the batteries when the car is off. So far the only configuration I've tested was to have the Link-10 meter hooked up by itself. You may remember that it reported 700 Watt/hours being drawn off in a 24 hour period.

The Link-10 will remain hooked up the entire time, after all, I need to monitor the pack during the test. But based on the previous test, we know the Link-10 brings along a 700 Watt/hour per day draw to the test. So I expect that if a component is drawing current, I should see more than a 700 Watt/hour per day reading on the meter.

Well, it's time to hook up the next item, and I need to choose which one. I still have to test the Zilla controller, the heating element, the charger and the DC to DC converters. Since the DC to DC converters have been fooled by the hot weather into thinking that they are too hot, their fans run constantly. So I think it's best I skip testing them for now. I think I'll move next to the heater.

Now the ceramic heater draws it's power directly off the traction pack, but it's behind two relays and a manual switch. In other words, in order for it to get any power, the car's HVAC fan has to be on, triggering the first relay. That makes the switch on the dash live. That switch must then be activated in order to trigger the final relay that actually sends power to the ceramic heater. So what are the chances that the heater is drawing any current when the car is idle? I'd say 0%, but I set out to test this methodically, and that's what I'm going to do.

I may not give the heater the full weekend to test it. If I see no change from the 700 Watt/hours I expect from the Link-10 in the first 24 hours, I'll add the next component and start the next test.

Didn't Make it to Laguna Seca

2010-07-11T21:40:00.000-07:00

Well, the REFUEL event at Laguna Seca went off today, and sadly I could not get there to participate. Over the last couple months, I reinstalled the motor and redid the front battery racks, getting the car fit and ready to participate. Where it all fell apart was in trying to arrange transport to get the EV Z3 to the track to participate. I don't own the right equipment and the cost of renting it was just not in the budget.

I'm hoping that there will be similar events here in Arizona in the future, but I'll just have to wait and see. I'd really love to get the car out on a track to see how it does.

On a better note, I took the car out for an extended drive early yesterday and found some interesting numbers. While here in the neighborhood, the car averages about 350 Watt/hours per mile (dismal). However, when out of the neighborhood, on surface streets, it averages about 250 Watt/hours per mile (better). The only thing that I can figure is the constant stopping and starting required by the high number of stop signs in the neighborhood take their toll quickly.

I believe the numbers can be better though. The transmission already has Redline transmission fluid in it, which reduces friction in the drive line. After I sent the transmission away to have the adaptor plate made, I filled it with Redline. I haven't yet put Redline in the differential, so I still need to do that. I don't know how much difference it will make, but it can't hurt. I'm keeping the tires at 45 PSI. The tire's maximum pressure is 51 PSI, so I'm well below the threshold, but they are certainly more firm than the normal 32 PSI.

There are two big things I need to do yet to help with efficiency. First I have to get the front end re-sprung. That won't affect the drive line, but it will get the ride height to the correct level. Once that is done, then I can have the front end aligned and take out any toe-in that's there now. I expect that will make the biggest difference of all.

So, why haven't I had the front end re-sprung yet? A couple reasons really. First, I had to take the car apart recently, you may remember. That hampered my ability to drive it anywhere. Second, the shop that can do it is in the middle of Phoenix, about 23 miles away. Now, the distance isn't a problem for the car, it can do 60 miles. However, the heat is a problem. It's been over a 110 °F lately, which makes for miserable driving when you don't have AC. Second, the little radiator and associated fans used to cool the Zilla have a difficult time keeping it cool in such high temperatures. I could drive the car there early in the morning, but by the time the car was done, I'd have to limp back home in the heat, doing my best to protect the Zilla. At this point, I'm inclined to wait until cooler weather comes so that I can get it there without any risk to the controller. After all, the car works great now, it just uses a bit more energy than I think it needs to.

Oh, and did I mention how much I love that new vacuum pump?

Stranger Still

2010-07-09T09:32:00.000-07:00

Let me say that the following series of events falls outside my official testing scheme. Circumstances this week have kept me from continuing along the "add one item at a time to the high voltage system" plan that I want to follow. That said, I find the following thing puzzling and not all together irrelevant.

Tuesday, I had to hook all the connections back up to the high voltage side so I could back the car out of the garage. It then sat idle, with the DC to DC converter fans running the entire time until last night. I took it for a ride and used up 1.7 kWhs. This morning, the meter read that the systems had drawn a total of 2.9 kWhs from the pack. I charged the car, and watched carefully to see how much energy the Link-10 reported going back into the pack.

If it behaved anything like last time, it would have counted back from 2.9 kWhs to around 1 kWh and then the pack would have reached it's peak voltage and the charger would start it's 10 minute decline to 0 current. However, this time it got to 0.0 (meaning the meter thought the charger had replaced all the current that had been used) and continued on. It reached +.02 or 20 W/hours before the charger reached it's voltage limit.

When it was all said and done, the charger had dumped approximately 3.4 kWhs into the pack. That means that the Link-10 had missed 600 W/hours in it's metering duties since it was last charged.

To recap, the last controlled event the meter showed that 2.5 kWhs had been drawn off when it was really closer to 200 W/hours. This time it showed that 2.9 kWhs had been drawn off when it was really closer to 3.4 kWhs. Like I said before, this doesn't fit into my official testing plan, but I think it is significant. It's showing me that the Link-10 is really giving me an approximation of the current drawn off the pack at best. More to follow.

On the bright side, the car is running beautifully. Although I'm hearing an annoying rattle that I have to chase down.

Of Questionable Metering

2010-07-05T21:39:00.000-07:00

As you all know, I decided that I needed to approach some of the small problems I'm having with a much better plan. Ok, a plan, seeing as how I really wasn't using a plan before.

First, I unhooked everything from the high voltage system with the exception of the Link-10 meter. I decided I'd leave it like this through the weekend and check in periodically to find out how much electricity was being consumed out of the pack. I was absolutely astounded to see that in the first day, 24 hours, the meter reported that 700 watt/hours had been drawn off the pack. I figured that simply couldn't be true. That would be the equivalent of a 30 watt bulb burning during the entire 24 hours. If it is being burned off, I don't know where. There's nothing moving, glowing or getting hot.

I left the system configured this way all weekend, and what I found was that the meter, rather reliably, reported 700 Watt/hours for every 24 hours the car sat idle. By the time I got around to charging it tonight, the meter read that 2.5 kWhs had been drawn off the pack. I hooked the charger back up to the battery pack and plugged it in. Now the charger puts out 27 amps at 160 volts, or 4320 watts per hour. At that rate, it should have taken about 35 minutes to get to full charge.

I walked into the house to finish a game I was playing with the family, walked out about 12 minutes later to find the charger had shut off. I measured the voltage on the pack and found that it was at 166.8, which meant it was on it's way down from the 168 that I charge the pack to. I took a look at the meter and it said that I'd only replaced 200 Watt/hours of the 2.5 kWhs that had been pulled out. That could only mean one thing, that energy had never been drawn out of the pack. At the most, 200 Watt/hours had been consumed, and I'm reluctant to think it was even that much.

That means that something in the Link-10 is doing something wrong. If you look at the screen that shows amps that are currently being drawn, it shows 10 milliamps are being drawn off at any time. But the Link-10 is converting that into 700 Watt/hours over a 24 hour period. Clearly a math error or something more serious. I may be contacting Xantrex about this one.

You may remember that I had noticed that when all the systems were hooked up to the high voltage system, I was seeing something closer to 1 kWh a day being drawn off. Well, I can now account for 700 Watt/hours of that in just the internal errors in the Link-10. I now need to hook up each component one at a time to find out what's responsible for the other 300 Watt/hours.

I Spoke Too Soon

2010-07-02T09:59:00.000-07:00

All is not well in the land of 12 VDC subsystems. I've always made a point of recording both the good and the bad on the car, and on occasion, the stupid things I've done. Get ready, cause this is going to be entertaining.

I need to give you a little back ground first. After I had taken the car apart, I found out that you're supposed to store these LiFePo4 batteries at a 50% charge if you expect to let them sit idle for over a couple weeks. Well when I started the dis-assembly, the batteries were at 90% capacity. Knowing that the repairs would take several weeks I needed to run them down, but how could I do that without the drive line in place. I hit upon the idea of simply running the heater system and burn it off that way. It worked beautifully. I was even able to predict within 5 minutes when the pack would be drawn down to 50%.

Before I started the heater, I had to connect the batteries I'd taken out of the car to the ones that were still mounted, hook the heater up to the batteries and the DC to DC converters up to the batteries as well. I carefully connected everything up, but I found something unexpected. I had hooked the positive lead to the DC to DC converters, and then put the multi-meter on the negative lead. I don't really know what I was expecting to find, but I can tell you it wasn't what I did find. I found that there was a positive charge on the negative lead. The positive side of the batteries was hooked to the converters, and I could read that positive signal on the negative terminal to the converters. The current was passing through the converters!

Maybe some of you reading this will say "Well of course it does." But I had no idea. That meant that when I hooked it up to the negative terminal, there was a nice big arc. No damage and all worked fine, but it still sucked.

Flash forward to this week. In deciding that I wanted to turn the DC to DC converters off when the car is off, I decided that I'd use two big relays; one on each side, positive and negative. I figured that way when they connected and disconnected at the same time, there'd be no time for a charge to build up in the converters and no arcing. Apparently that was wrong because in about 5 or 6 cycles, I managed to weld the contacts for both relays closed.

OK, so now my solution for shutting off the DC to DC converters isn't working. I'm thinking that some heavy diodes might solve that problem, but I'm not sure. But it turns out that all of the work I did yesterday was the result of an assumption and I dare say, a stupid one at that.

You see, ever since the car first hit the road, I noticed that sitting idle and off, the meter would show that 500 to 600 W/hours had been consumed in a 12 hour period. Now, there are 5 things hooked to the high voltage side on the car: the Zilla, charger, DC to DC converters, the ceramic heating element and last, the Link 10 meter. I had always assumed that the vampire in the car had to be the DC to DC converters. This past week I even disconnected them so that I could test whether the little 12V SLI battery could handle the car's load while the converters were disconnected. I dutifully measured the progress of the SLI battery on it's march to death (rescuing it well in time). But since I disconnected the converters by tripping the emergency disconnect switch, I got no data on the Link 10 to show if the pack had gone down. I just assumed that it hadn't! That was a mistake.

Last night, the car sat for 12 hours with the SLI battery powering the 12V system and the DC to DC converters off (a flick of one of the relays freed it and broke the connection). When I came out this morning, I found that 500 W/hours had vanished. Well, it clearly couldn't have been the converters, they were off! That's when I realized that I'd been guilty of some very poor troubleshooting practices.

OK, so what to do? Well, I've now tested one of the components that is hooked up to the high voltage system, and found (to my surprise) that it's not the energy vampire. Before I move any further, I have to explore all possibilities. As far as I can work out, the possibilities are either one of the other components is burning off that energy, or the Link 10 is reporting that the electricity has been used, when it really hasn't been. I think it's safe to rule out a short in any given battery as I tested them all after I assembled the car and found they were all the same. If it were a battery, that one would be dead.

So, what to do about it? I think the first thing is to test the Link 10. Right now, the high voltage pack sits in the car with the Link 10 being the only thing connected to it. I should know in 4 or 5 hours if it's going to report any draw down on the pack. If it does, I'm left with the task of determining whether the Link 10 is responsible for using up the energy (unlikely) or simply reporting it wrong. If it reports no change, I'll know that I can hook up one more item. I'll keep doing that until I find the culprit.

So, what have we learned today? Don't make assumptions when troubleshooting! Now if you'll excuse me, I'm going to go write that on a black board a few hundred times.

12 Volt Dilemma Sorted

2010-07-01T16:26:00.000-07:00

Yesterday afternoon, I pointed a large box fan right into the trunk, set it on high and let it run for an hour. I wanted to find out if the fans on the DC to DC converters would turn off if they had enough fresh air. They get fresh air now, but this would be a lot more. The question was, are the fans running continuously because they aren't getting enough fresh air, or because the ambient air isn't cool enough to actually cool them. Well, after an hour, I turned off the hurricane directed at them and found the fans were still humming away. So, 100 °F is simply too warm to cool these devices properly.

Last night I let the car sit with the DC to DC converters on and the 12V SLI battery connected. In the morning, after 12 hours of idle time, I found they had consumed 600 W/hours. To recap, without the SLI battery connected, they consumed 5oo W/hours, and with them off and the SLI battery handling the load, the car consumed 44 W/hours from the battery.

In light of those two discoveries, I made the rather easy decision to hook the DC to DC converters up to a contactor that's triggered with the ignition key. I want them off when the car is not running. It took a few hours to route the wires and such, but in the end it worked out ok. The new contactor is sitting atop the SLI battery in the right corner of the trunk. It's out of the way and should be safe from anything rattling around in the trunk.

The one thing that I'm going to have to watch carefully now is the voltage on the SLI battery. I'm asking more of it now since it will be providing all power to the car when it's off. Sure, it's not much, but in 3.5 days, it will draw that small 33 amp/hour battery down to 10.5 Volts. I have a battery tender that I'll be hooking up to it. When ever I plug in the car to charge it, I'll plug in the battery tender for the SLI battery to keep it healthy for any extended stays in the garage. One extra plug and the energy it will draw is so minute as to be nearly negligible.

This evening, I'll be taking the car out to a nearby park to take some glamor shots. The car is going to be featured in a book about conversions, with a section dedicated to particularly interesting ones. The EV Z3 is going to be in that section. Is that cool or what!?

First Day Drive Report

2010-06-30T11:03:00.000-07:00

The first day on the road was nice in many ways, but had a few drawbacks that I'll discuss in a moment.

The car is quieter than ever. The new vacuum pump seems to have two stages. The first stage, and loud one, seems to draw the vacuum down pretty quick, but then it switches to a different mode where it becomes much quieter and to finish the job. It's important to note that when I say "loud stage", that is relative. It is still 1/3 as loud as the old pump. The nice thing is that it never seems to go all the way back to the first stage in normal driving. It just kicks in with the second stage when I hit the brakes. It's so quiet, I can't hear it in the car. I can feel it in the floor, because it's mounted very near my feet, but I can't hear it at all. I couldn't be happier with the new pump.

The drive line is beautiful. There is no wobble, which I expected, but it's actually smoother than before. I'm not sure if this is due to the fact that the motor is better balanced than before, or because the flywheel is absolutely balanced now. My bet is on the flywheel. In either case, it's great!

On the very first drive, I pulled into a local shopping center, and a mother was waiting to cross the street with her little girl. They paused and waited for me to pass, and I parked near by. The mother then told me that her daughter thought my car was very pretty. I thanked her and told them that it was also electric. The mother stopped dead in her tracks and said "You're kidding." "Nope!" I replied. She simply said that it was cool and amazing. A nice little interaction.

Now for the rough bits. Driving in Phoenix, in the summer time, at 1:30 in the afternoon, with out AC sucks. There is no other way to put it and no way around it. It was 110°F in my back yard before I left, which meant it was easily 115°F on the black top. It takes almost no time at all for a person to get really sick of that.

Apparently, the Zilla does not like it either. Towards the end of the trip, I noticed the "Check Engine" light flashing slowly. While I can't say with certainty that it was caused by high temperatures, based on a number of factors at the time, it certainly seemed it. I didn't have a chance to get the error codes off the hairball before they'd been pushed away by different ones (I was doing a little experimenting). But I did put my hand on the controller to check and found that it was too hot to leave my hand on it. I measured it with an infra-red thermometer and found it was a 126°F. I verified the pump for the water cooler was working and the fans mounted to the small radiator were spinning. All is working, it's just too damned hot.

Sadly, adding AC to the system is only going to make things worse. I have no where to put the radiator for the Zilla except for behind the condenser for the AC system. So if that starts spewing out heated air from the AC system, the Zilla will over heat for sure.

The DC to DC converters continue to run their fans non-stop. The ambient air temperature, coupled with the heat they generate while operating must be above the temperature threshold. I'm not sure I can do anything about this. I'm going to prop a fan on a chair and point it straight into the back of the trunk. If they shut off, I know I simply need to find a better way of circulating air through there. If they don't, I'm not quite sure what I'll do. I let them run for 12 hours and found the fans and the DC to DC controllers sucked a full 500 W/hours from the main pack.

I'm still working on getting data on which will be the best way to go with the 12V system. Should I disconnect the DC to DC converters when the car is off, or the SLI battery? I have two pieces of data now. The one I mentioned in the last paragraph, though it's important to note that this was with the 12V SLI battery disconnected. If I shut down the DC to DC converters and let the battery handle the load, the car draws off only 44 W/hours. That tells me two things. One, at first glance relying on the SLI battery would seem to be the way to go; and second, these Iota DC to DC converters are energy hogs! I have more data to gather though before I make my final decision, and I'll share that later.

We're Back On the Road

2010-06-29T09:36:00.000-07:00

I finished up a few things with the car this morning and then began the process of taking it down off the jack stands. Once it was on the floor, I started it up and drove out of the garage. No problems, on issues.

I took the car for a little 3 mile run, just testing out the drive line. It is as smooth as silk. No wobbles, and it shifts beautifully. What a relief and what a great feeling! I brought the car back and plugged in the charger. While I'd been working on the car, I'd made sure to keep the batteries at 50% capacity, which is the recommendation if you're going to store them for over a week or so. So now I need to charge them up.

I'm definitely going to have to do something about the 12 VDC system. The DC to DC controllers have decided they don't like the ambient air temperature here in Phoenix in the summer, so they run their cooling fans constantly. That could be a real problem if I park the car for a while.

I decided to simply disconnect them when the car was sitting idle over the weekend and let the small SLI battery take the load for any 12 VDC demands. In the 64 hours that it was running the show, it dropped from 12.8 VDC to 12.0 VDC. I need to figure out how much energy was consumed during that time. There is a lot to consider and a lot of data I need to gather before I decide what I need to do. But for the mean time, I'm going to have to watch the traction pack when the DC to DC converters are on, or watch the small 12 v SLI battery if I disconnect them. I'll keep you all posted.

But these are minor issues. The EV Z3 is back on the road!!

All Systems Go

2010-06-25T09:25:00.000-07:00

I ran a final check of the 12v wiring this morning, and after I was convinced everything was OK, I connected the 12v SLI battery. The car came to life just as one would hope. All systems checked out. With a couple minor adjustments, the 12v system was healthy and ready to go.

I ended up needing to move the proximity switch for the power steering pump about 1/8". The power steering pump wasn't cutting off. I also had so shim the aluminum plate that the vacuum pump sits on because it was rattling and making a lot of noise. I shimmed it, and anchored it down, and now the new vacuum pump is so much more quiet than the old one. It was worth every penny.

Once I was happy with all the 12v systems worked, I turned my attention to the high voltage system. I double checked everything and threw the breaker. No big arcs, and no loud pops, so that's good. It was time to start the car up. A twist of the key, a click of the main contactor, and the car was live. I gave it a little throttle and the wheels started spinning. Excellent!!

Now for the real test. Was there any more wobble in the drive line? I revved it up to 4000 RPM and... smooth as glass. Then I ran it through the gears to be sure the clutch was working OK. Everything checks out.

I have a few more things to do before I take it down and drive it. Unfortunately, no time to do any of that until next week. *Sigh*

Good Progress

2010-06-24T19:28:00.000-07:00

The batteries are all in place and anchored down.

Here's a shot of the front with all the batteries in place and anchored down. I've run new testing wires from each group of four batteries up to the little bus bars that are anchored on the back of the front rack and the front of the back rack. I've included a 2 amp fuse in line on each lead from the positive side. Any short will quickly blow the fuse and keep the wire from melting down and starting a fire.

Here's a shot of where I placed that one (ahem) extra battery. On the right is a shot of the battery box in the trunk as it was when I first finished it. On the left you can see the extra battery pushed down in the gap at the end of the box. It worked out very well, and was easy to get into place and clamp down.

After I hooked them all up, I went through and took a voltage reading on all the batteries. After sitting for over two months, with 2/3's of the batteries sitting in a box and the rest still wired up in the car, they each read 3.29 volts. I suppose I had no reason to expect anything different, but I couldn't help being impressed. These really are great batteries.

I want to go through and re-verify and recheck all the connections for the high volt system and the 12 volt system before I replace all the fuses and throw the breaker. I should be able to get that done early tomorrow. There are still a few things I need to do after that and before it comes off the jack stands, so a Friday launch is looking unlikely. But that's OK, I should be back on the road next week. Can't wait to feel that EV grin again!

Apparently Late Night Math is Not My Strong Suit

2010-06-23T18:05:00.000-07:00

Lots done today. Let's take a look at some of it.

This is the new location for the shunt. It's at the front right corner of the back battery rack. I had to cut and re-crimp a couple cables to get them the right length, but it worked out well.

Just to the left of that is the emergency breaker, or battery disconnect. I had thought that I'd mount it dead center on the back rack, but the cable for the positive feed to the contactor didn't reach the extra 2 inches. The symmetry in the engine bay will be off, which is kind of too bad.

Here's a shot of the new throttle assembly set up, installed and tested. It's difficult to make out what's what here, so I'll take another once the batteries are in. But you can see the cable anchor in the right side of the picture, and the pedal assembly just to the left of center.

And last we have a shot of the whole assembly mounted in place with the back row of batteries resting in their place as well. There's a bit more tie down work to do, then I can install the front row.

In addition to all that, I also got a few other things done. I re-installed the tray under the motor that holds the fan for the motor as well as the box that contains the new vacuum pump. I ran all the necessary power lines to the items and the vacuum line from the pump to the reservoir. I also installed the new cross brace that stiffens the chassis.

I don't think I mentioned it before, but the fellow that owned the car before me clearly ran it up on a curb or something. There was a bit of damage under the car, mostly cosmetic. However, the original cross brace took most of the abuse, and was a bit twisted. It still fit in place, but was very difficult to bolt in and was under stress once in place. The new one slipped on so easy, it was a pleasure bolting it on the car.

Which brings me to the odd title of this post. You may remember that I had 31 batteries up front in the original configuration. During the rework, I drew up multiple designs trying to get the cleanest install of all the batteries in as tidy a package as I could. Well one night, very late I came up with this design. It is the cleanest by far and I'm very pleased with it. There's just one nagging problem. There are 12 batteries in the front row, and then two rows of 9 in the back rack. In most worlds, that adds up to 30. Apparently for me, in the middle of the night, that sometimes equals 31.

For the life of me, I don't know why I never added them up again, but I didn't. (This is the part where you all laugh at me.) After standing and shaking my head in disbelief, I started laughing at myself. But eventually I started thinking about it objectively. This really was the cleanest design I'd come up with, and it's going to look great. I don't think I want to change it, or would have if I realized it at the time. There is room for one more battery in the trunk box. It will make the end of the box a bit cramped, and I'll have to redo some of the lines in there, but I think it's going to be worth it in the long run.

The worst thing is that it will delay my relaunch by a day or so.

Odds & Ends Part XIII

2010-06-22T20:54:00.000-07:00

Lots to report today, but sadly no pictures. You'll just have to imagine how stunning the work is.

I finished the straps and mounting system that will hold the batteries in the rack that will be mounted over the motor. I still need to figure out how I'm going to get some brackets around the batteries to keep them compressed. I had it all worked out in my mind how I'd do it, but once I started working with the rack, I realized what I had in mind just won't work. Funny how that happens, you tend to not see in your mind's eye how different pieces will interfere with each other until you start assembly. Anyway, it shouldn't be to hard to sort it out, I'll just have to come up with something different.

Once I had all that done, I placed the rack in it's space so I could start figuring out how I was going to place some of the elements that have moved. I need to find new locations for the Link-10's shunt, the emergency disconnect, the bracket to hold the traction pack fuse and the anchor for the throttle cable. You may remember in a previous post I built the mount for the throttle pedal, but I hadn't built anything to hold the assembly that anchors the cable.

The shunt's new home was easy enough. It's going to be roughly in the same location it was, but I had to cut a small piece of angle aluminum to mount it to. Just out of dumb luck one of the new braces used to hold down the batteries was in the perfect spot to anchor the throttle cable. So that's sorted. Last I had to build a small bracket to hold the emergency disconnect switch on the front the new tray. I cut, drilled and had the whole thing mounted, and it looked great. Then I screwed on the big red knob that you slap to break the connection, and realized that I wouldn't be able to slap it down because it ran into the tray. I'm not sure if I'm just working too fast, or why I'm making such silly mistakes. Fortunately, it will be easy to fix that as well.

In addition I reconnected the lines to the reverse switch in the transmission. I really wish I had the proper connector to connect it up. I found the connector online and numerous places that sell it. It's about $4.00 or so, and it's made by Tyco. Would you believe every place that I could find it, it was out of stock, and had a lead time of at least 4 months. Apparently Tyco makes one batch a year and when they're gone, you wait.

I also ran an auxiliary 12 vdc line to the back of the car. This line is switched with the ignition. One of the things I found in the 2 months I was driving the car was that if the car sat idle for 24 hours, the 12 volt system would manage to drain about 1 kWh out of the traction pack. There are only a few things actually drawing power when the car is off, and they are drawing tiny amounts. The one thing that is on, however, are the DC to DC converters. They are providing 13.2 vdc to the car, as well as the SLI battery.

I know that you can leave a trickle charge on a lead acid battery forever, and it will always draw just a bit of power. I don't think they'll draw 1 kWh in 24 hours, but something is. I think it's either the DC to DC converters just using it up because they are inefficient, or the SLI battery is drawing it off. I'm just not sure, so I'm going to run some experiments. I'll disconnect each, one at a time, and watch what happens to the traction pack. When the SLI battery is disconnected, I'll look to see what happens to the traction pack and then I'll disconnect the DC to DC converters and see what happens to the SLI battery. If one of them is the culprit, and there appears to be no adverse affects to disconnecting it when the car is off, I'll use that new 12 vdc line to run a separate contactor that will disconnect the appropriate component when the car isn't running.

Lets see, what else is there to report. Oh, I also cut some plate aluminum to fit over the ends of the batteries in the front tray. This will make it easier to clamp them down and compress them. I still have to build that apparatus though.

Ok, that's it for today. Stay tuned because I'll have lots more to report tomorrow and I'll have some pictures up to show the progress.

Front Battery Tray

2010-06-17T15:57:00.000-07:00

Today I finished building out the front battery tray. Here's a shot of the assembly sitting on the garage floor.

Later, in the afternoon, I got the whole assembly mounted in the car.

That involved doing some minor, but time consuming work on the mount for the power steering pump. I had to keep it in the same position in the compartment relative to the steering rack. So even though the battery rack moved forward, and the pump had been attached to that rack before, I needed to keep the pump from moving along with it.

Now I just need to mount the back tray, secure the batteries to it, run all the interconnects, find a new location for the shunt and the emergency disconnect and then finish the mount for the throttle assembly. Then I can start checking all the wiring and start testing things. If all goes well, it will be out of the garage sometime next week.

New Battery Rack is Done

2010-06-15T14:06:00.000-07:00

I didn't post much last week because I didn't work much last week. At least not on the car. 60 hours at work kind of steals all your time. And much of your will to live. But that's all behind us now and I'm back to working on the car!

The battery rack that will be mounted over the motor is done!

In this shot the part nearest the front of the picture will mount closest to the fire wall. I've placed a couple batteries in it so you can get a sense of scale. You might have noticed a slight rise in the cross beam the batteries rest on. There was no way to mount them straight across because the motor was in the way. Those cross members have a five centimeter rise from the edge to the center of the rack.

I also worked out the throttle assembly which is mount on the left side of the rack. Here's a shot of the left side.

I need to build some sort of enclosure for the throttle pedal to keep the dust and water off of it. On the opposite side, I need to mount the shunt for the Link-10 meter. That should be pretty easy, it should bolt straight to the new frame with out any problems.

I've built the rack big enough that I'll still have room to use some of the clamps that came with the batteries so compress them together, helping to prevent them from swelling (as one astute reader pointed out). I may need to address that issue for the batteries in the trunk box at some point as well.

Perhaps the best news is that I've realized I will be able to use the existing front battery tray the way it is, with only some minor modifications. When looking at my measurements of the space from before, I neglected to take into account that they included the white plastic boxes the batteries were originally mounted in. Well, I won't be using those boxes which means I gain 1/4 of an inch. Along with moving the front rack back by about an inch, I'll have about 1.25" between the top of the battery strap and the hood. In fact, I will be able to put the sound deadening cushion that was affixed to the bottom side of the hood back on, with room to spare.

But the best thing about that is that I don't have to re-figure and rebuild the brace that holds the power steering pump, which is suspended below that rack. I was at a loss for how I was going to handle that, but now I don't have to at all. It just means I'll be back on the road that much sooner.

New Battery Racks

2010-06-08T20:16:00.000-07:00

Loyal readers will remember that I've decided to take this opportunity to redo the battery trays in the front of the car. Since I had to disassemble the entire front of the car anyway, I figured now was the time to do it. Of course I should mention why. Two reasons really.

First, I've come to find out that these batteries really are supposed to be mounted vertically. Originally, I'd read it didn't matter, and you could install them in any orientation you wanted except upside down. But since then, I've seen in multiple places that if you don't mount them vertically, the electrolyte will pool to one side of the battery, shortening the batteries life. Well, I thought the electrolyte was a paste, but I turned one on it's side the other day and could hear a faint but distinct gurgling coming from the battery.

Second, when going through the pack with a wrench trying to tighten the lugs on the batteries, I found it extremely difficult to get a wrench on some of them, and in fact, I couldn't reach 7 or 8 of them at all! That meant over time the constant heating and cooling of the terminal would cause the lug to work it's way loose (I already saw this on the lugs I could reach) eventually creating enough of a gap that there would be arcing and eventually fire. So, vertical it is!

Here is a shot of the work I did today. there will be more horizontal pieces running between the sides. Three to be exact. They will support two rows of 9 batteries just over the motor. That means I need to find room for 12 more. As it happens, the space just behind the radiator, and in front of motor is wide enough (by 4 mm) for 12 batteries. So they should all fit pretty well, plus I got rid of some steel that weighed quite a bit more than the aluminum.

I'm also taking this opportunity to replace the vacuum pump that I've come to despise so much. It is by far the loudest, most annoying thing on the car. I'd bought the pump off of eBay about a year ago for the bargain price of $110. It was one of the few parts I thought I could save money on because a vacuum pump is a vacuum pump. Right? Well it turns out there are pumps that are a lot quieter.

Here you see the original one on the left. It measured in at a wopping 74 dBA. The new pump on the right puts out a relatively quiet 58 dBA. The dB scale is logarithmic, and every 10 dB increase means that the sound you perceive is twice as loud. So this new pump will be roughly 1.6 times quieter than the old one. Was that worth the $300 I laid out for it? Well, let me throw this little bone into the mix. The old pump drew 8 amps, the new one, 2.5 amps. Now are you impressed? I thought so.

The old one still works great, it's just loud. I'll probably put it back on eBay.

WarP Drive is Engaged

2010-06-02T17:47:00.000-07:00

Let me start out by saying that I debated long and hard with myself whether I should use such a nerdy title for this post. In one regard, it's beautifully elegant and accurate in it's description of the current situation. On the other hand, it betrays the fact that I am a big dork. But, when it comes down to it, you must be true to yourself, so dork it is!

The motor is back in the car! I spent yesterday afternoon bolting the adaptor plate, hub, flywheel, and clutch up to the motor. Today I mounted the transmission to the motor assembly and then, with my dad's help, lowered it into the car again. I desperately hope that I never have to remove it again. But if I do, at least I'm getting good at it.

I got the linkages for the shift knob connected, and everything seem absolutely great at this time. Once it was all bolted down, I took some of the cardboard templates I'd made while waiting for the motor's return and started placing them in the engine compartment trying to sort out battery layout. It's looking more an more like getting all 31 batteries up front and mounted vertically is going to be easier than I'd first thought.

There's no question that I have a lot to do, but I'm going to attack it pretty aggressively over the next few days. I don't really know how long before I'm back on the road. I'd hazard a guess of more than two weeks and less than 3, but we'll see.

The Return of the Motor

2010-06-01T11:06:00.001-07:00

The FedEx truck pulled up moments ago, and that could mean only one thing. The WarP 11 has made it's way back home. Wouldn't you know it, the same malcontent that picked it up when it left, lumbered out of the cab to deliver it. Sadly, his mood hasn't changed. Fortunately his sour attitude can not dampen my spirits; the motor is back and I can start the assembly process!

I mentioned before that I'm going to redo the battery layout. I may need to redo a couple other things to get the fit right. Stay tuned for all the fun :)

A Very Good Call

2010-05-28T13:31:00.001-07:00

I received a call from FedEx late yesterday. They wanted to schedule a delivery from Warfield Electric for this coming Tuesday. The motor is on it's way home!

I'm astounded that the motor got back to Illinois, was repaired and will be back in my garage in 18 days. I'm not sure how NetGain and Warfield Electric pulled that off, but I'm ever so grateful to them that the have.

I should be able to get the motor back in the car by Wednesday, and then I can begin in earnest, the work of rebuilding the brackets and supports for the batteries.

What To Do, What To Do

2010-05-26T16:08:00.000-07:00

I realize I haven't posted anything in a while, but that's because I haven't really done anything. I'm waiting for the motor to find it's way back here, and until it does, there isn't much to do.

However, there are a few things, and there's some news to share. A friend of mine responded to my requests for suggestions about where I might get some hard rubber for a new motor shim, or more specifically what I could use. He'd suggested using a piece of a tire from a lawn mower. I went to the hardware store and found a 14" hard rubber tire that looked like it would work perfectly. At only $14 and change, I decided to go for it.

I realize this my not be the most glamorous looking thing, but I think it's going to work out very nicely. At the bottom of the shot, you can see the piece I cut out of the tire. I cut the rubber off of the inside diameter exposing the inside of what was the hollow space in the tire. Once I press it flat, it's the perfect height to shim the motor, and it will provide some of springy support. The bulk of the motor's weight will still be supported by the original motor mounts that supported the original engine just like before.

I also spent some time making some cardboard cutouts of battery layouts. I simply placed the batteries on the card board in configurations I think will fit in the car, and cut them out. I want to fit the original 31 batteries that were up front, back in, but I want to get them all oriented so they are vertical, not prone like before. It's going to be a tight fit, but when has anything in this car not been? It's tough dealing with tight fits in millimeters, especially when you're only 5 millimeters short for what would other wise be a perfect fit.

I mentioned that there's some good news as well. One of the things that has surprised me, is the number of people that have contacted me to tell me how much they liked the car, or admire the work I've done. It's always great hearing from different people, and to hear their stories. I hate to be so bold as to think I might have influenced some people to undertake a conversion, but in the long run, I hope it does. Even with this little set back, it has been an incredible amount of fun.

Just last week I was contacted by someone who is writing a book of some sort about electric cars and conversions. He wants to include pictures of the EV Z3 as an example of an interesting conversion. Let's face it, there are plenty of Ford Rangers and Chevy S-10's that have been converted, and while they are interesting, they are no Z3 ;-) I'm in the process of getting some photos together for him. We'll see how many make it into the book. I'll be sure to keep you all informed.

On a slightly related note, I did receive one bad piece of news today. Now that I've finished the car (current issues aside), I'd really love to charge it with solar power. I called a local company that does solar PV systems so I could get a quote and find out where I stand. It looks like my home may not be a good candidate. My roof doesn't have a surface that faces South. It does have surfaces pointing East and West. Apparently in lieu of South, West is most desirable. Unfortunately, because of a bend in the street, mine is actually angled a bit toward the North. It would still work, but if it's too far North, it will greatly reduce the incentives paid by my local utility to help defray the costs. I'll know more when the representative can come out and actually measure the azimuth.

That's all for now. I've got a few more things I can do while waiting for the motor's return, so I'll be working on them as I can, and I'll post all the details.

The WarP 11 Has Left the Building

2010-05-15T06:49:00.000-07:00

Friday afternoon, the surliest Fed-Ex employee ever stopped by to pick up the motor. It only took 10 minutes to get the paper work sorted out and get the motor loaded on the truck.

It took me the better part of a day to pack it. I no longer had the original box and packing material that it was shipped in, so I had to fabricate one. I put in multiple layers of cardboard and foam on the bottom and sides, and made some sturdy cardboard wedges to hold it in place in the middle of the box. It's packed in very tight and shouldn't move around during shipping.

I'd wager that it's going to make it back to Illinois safe and sound. Unless, of course, it takes damage from just being in the presence of such an overwhelmingly bitter and hateful Fed-Ex delivery man.

Soliciting Ideas

2010-05-13T11:39:00.000-07:00

I finished packing the motor today and the pickup is being scheduled. Soon it will be on it's way back to Illinois for repair. Hopefully, it will be back home before too long.

After I took the motor out of the car, I got to looking at one of the brackets that I made. This bracket is simply in place to hold the motor the proper distance off of the sub-frame so that the drive-line lines up correctly. Here's a shot of the bracket:

It may be ugly, but it works fine. Here's a shot of it in place:

You can see it resting there just on the top of the sub-frame. In fact, you can see that the holes in the bracket line up with the holes in the sub frame. What that allowed me to do was wrap a piece of steel around the motor and tie it down to the sub-frame so that it can't go anywhere. Now that is not the primary motor mount. There were brackets in place that tied the motor directly to the old motor mounts to prevent the motor from rotating under torque. The strap just held it down to the bracket.

Anyway, the reason I'm showing you this, is because when I took it all apart, I got to thinking that this particular support might be better as a piece of hard rubber, rather than steel. I'm just thinking that a certain amount of give, which would help cushion the motor from bumps and what not, might be better. I don't think this had anything to do with the motor's failure, but if I can make life for the motor any easier, why not.

When I say hard rubber, I'm thinking of something like the heel of a men's dress shoe. So my question to all of you is do you have any suggestions of where I might find a piece of hard rubber that's about 1" by 2" and roughly 12" long? Many of the things that have gone in the car I've used in a way that wasn't intended by the manufacturer. I've had to be creative. The trouble is, I just can't think of anything that has that type of rubber in the size I need. If you have a suggestion, post it in the comments. I'd be very appreciative.

News on the Motor

2010-05-10T13:39:00.000-07:00

I got an answer from George at Netgain, as to what that stuff was that was laying in the bottom of the motor. Apparently all that debris is balancing putty. Well, that explains everything nicely! It totally makes sense now. Why the motor and clutch were balanced at first. Why it seemed to fall out of balance all at once.

Without a moments hesitation, Netgain has told me to prepare the motor for shipment, they're sending someone to pick it up to take it back for repairs. Now that's customer service!

It's sad to see it go, but I'm thrilled at the prospect of getting it back balanced, strong and ready to go back in the car.

Now onto some other improvements on the car while I await the return of the motor.

More Bad News

2010-05-07T20:44:00.000-07:00

Fresh off of yesterdays relief that the balanced flywheel was back on comes this disappointment. I had mentioned that there was still a bit of vibration from the motor and that I wasn't going to worry about it. Well, that turned out to be more wishful thinking than anything, and profoundly wrong. It is definitely something to be concerned about.

While working on the motor I had dented the steel shroud I'd made for the forced air ventilation for the motor. I decided to take it off and fix it. When I did, look what fell out:

I'm not entirely sure what that is (the dime is for scale, it wasn't in the motor). It's not metallic, or at least it's not magnetic. It looks like some sort of hard baked plastic. In either case, I'm pretty sure it's not supposed to be rattling around in the motor, in pieces.

For the most part, the motor is sealed. I have the shroud on one end that allows me to force air into the motor to cool it, and there is a 1/8" mesh screen on the other where the air comes out. There's no way for anything to get in there to cause damage. So it would seem that what ever that is, failed on it's own, and failed catastrophically. I guess that explains why I didn't start noticing any vibration for several weeks while I'd been using the car. The flywheel didn't just fall out of balance, the motor did.

I have an email in to the fine folks at Netgain. I'm sure they'll be able to tell me what's going on and help me get it fixed. One thing is certain, and that is the EV Z3 is not going to be back on the road for a while. I plan to use the down time to do some other improvements to the car, so stay tuned.

Good News Everyone!

2010-05-06T12:29:00.000-07:00

Well I bolted the flywheel up to the motor and spun it up. What a difference! The wobble was almost entirely gone. There is still a small vibration at around 500 rpm while the motor spins up, but when the RPM's climb just a little higher and beyond, it is as smooth as glass.

Now I just need to get the pressure plate mounted back up and start re-assembling the drive train. Mounting the pressure plate is going to be tricky as it is naturally sprung to push on the clutch disk, meaning I have to collapse it about 1/2" to get it on. When it's new it has a retaining system that holds it until you bolt it up, making it easy to get it on the flywheel. Well, that's gone so this could be tough.

A Slightly Lighter Flywheel

2010-05-05T22:07:00.000-07:00

I got the flywheel back this afternoon and it had about 6 grams of material drilled out of the side.

The machine shop was able to get it down to only 0.2 grams out of balance. That's like a smear of grease. Anyway, no time to hook it up this evening. I'll put it on tomorrow and report back as to how stable the assembly is.

The Flywheel is at the Shop

2010-05-05T10:03:00.000-07:00

That sounds like a pass code phrase you'd hear in a bad spy movie. Anyway, the flywheel is in the shop, and they are going to put it on the machine in the next couple days, to test it and balance it.

While I was there the machinist said something that's got me a bit worried. He looked at the flywheel and said that he'd be surprised if it was out of balance because it was a "zero balance" flywheel. He asked what it's bolted to. I explained how the taper-lock hub mounts to the motor and the flywheel to the hub. He asked if there was any chance the hub was out of balance.

The truth is I have no idea if the hub is in balance. I mentioned yesterday that the motor did vibrate a bit once I'd removed the flywheel. Could that have been caused by the hub being out of balance? I just don't know. There was definitely an improvement in balance when I removed the flywheel. That stands to reason that it was part of the problem.

Let's suppose the hub is out of balance. The question becomes would the flywheel being bolted to the assembly exacerbate the small wobble I saw once the flywheel was removed? It stands to reason that if that were the case, having the clutch plate and disk bolted to the assembly would make it even worse. That's not what I saw. There was no appreciable change in wobble between having the clutch plate mounted and not.

If they find the flywheel is balanced and the problem becomes the taper-lock hub, I'm not quite sure what I need to do to get it fixed.

UPDATE: The shop just called to tell me that the flywheel was indeed out of balance. 6 grams to be precise. I should have it back this afternoon and I can mount it up and see what we get. Stay tuned.

Motor Pull

2010-05-04T15:26:00.000-07:00

Funny, you usually see an entry in and EV blog called "Motor Pull" as one of the first entries. Certainly not one after the proud builder has put only 901 miles on the completed car!

OK, enough grousing. Here's the, once again, empty engine bay.

My dad was kind enough to come over and help me get the motor out of the engine bay. It was quick work. I had everything disconnected by 10:30 and we had the motor out 1/2 hour later.

The first order of business was to start testing. We pulled the transmission off of the adaptor plate to expose the clutch and flywheel. I secured the motor and we spun it up. Sure enough, there was the wobble. It took a while for the 12 volt battery to spin it fast enough to see the wobble, but it got us there.

Next, we took off the pressure plate. So only the fly wheel was mounted to the hub. We spun it up again and... wobble. OK, so now we can check off the pressure plate and clutch disk as the cause. Next we removed the flywheel, leaving only the motor and the hub.

We put the battery on it again and watched carefully. There was still a bit of wobble, but it was substantially less. Perhaps 85 to 90% of the wobble was gone with the flywheel off. So, here's the culprit:

I was kind of surprised to see that there was some wobble with the flywheel off. I did what George from Netgain suggested. I spun it up and looked straight down in the hub. There was no sign of movement at all. I held a piece of aluminum right next to the side of the hub as it spun to see if it rubbed periodically or consistently. There is no variation in the spin at all. Perhaps the slight wobble that we see is from a slight imbalance in the motor. All I know is that it is very minor and there is absolutely no play in the shaft or bearings, so I'm not going to worry about it.

Next I need to get that flywheel down to a shop that can balance it.

Disassembly

2010-04-29T11:32:00.000-07:00

I put the car up on jack stands yesterday and began disassembling it this morning. So far so good, but it's been very slow going. I'm not sure if I should be proud of how well built and how secure everything is, or ashamed it takes so much work to take it all apart. I used to curse engineers that made working on cars this difficult. But then I'm not an engineer, so I guess some slack is in order.

The batteries are out of the first two trays. Later I'll tackle the back box.

I received some encouraging words from George Hamstra at NetGain Motors. I wrote to tell him of the vibrations and that I'm taking the car apart to fix it. I'm worried that the motor may be damaged, which is causing the vibration, or that the out of balance clutch assembly might have damaged the motor. He said that it was highly unlikely that the motor was damaged, especially if I caught it in time. I'd put less than 100 miles on the car since I first noticed it, so I think I should be good. As soon as it's out, I'll test it and report back.

I'm thinking the reason it's gotten worse is likely due to the failure of the pilot bearing that's seated in the hub assembly couples with the transmission shaft. It was new when I put it in and probably helped to mask or limit the vibration. But I'll know more when it's out and I can see.

One thing I haven't mentioned is that I'm going to take this opportunity to improve the car a bit. I'm going to redo the lay out of the batteries in the front end. When I decided to go with lithium cells, I'd already designed and built all the supports for the lead acid. I had figured there was no need to redo the existing supports, so I worked to get the lithium cells to fit into what was already there.

Later I realized the mistake I'd made, it posed two problems. First, there is some debate as to the proper way to orient the batteries. People weigh it on both sides. Some say that you can orient them anyway you'd like and it won't harm them, while others say you MUST keep them upright. The truth is that no one knows for sure. But there is one certainty, and that is the manufacturer says they should be mounted upright. I haven't seen any elaboration on why, but if they say it, that's good enough for me.

The second reason is ease of accessibility. Every month (twice) I'd do some basic maintenance on the car, checking for loose nuts and bolts, and making sure there were no other problems. I'd also tighten all the bolts securing the copper straps that connect all the batteries. You'd be surprised how much they can loosen up in that time. Well, I'd check all but about 7. There were 7 I simply couldn't get a wrench on. I realized early on that this was bad and that I'd have to do something about it. So now I get the chance to do just that.

I think I've figured out a lay out that will accommodate all the batteries in the engine bay, let me get to all the things I need to get to and still let me shut the hood. There will be much more on this as I progress.

Bad News Everyone

2010-04-26T15:38:00.000-07:00

I'm afraid I have no good tidings today. Let me get straight to the meat of the story.

Last Sunday, I left the house in the Z3 with the usual EV grin on my face. A few houses down I noticed a slight vibration through my hand resting on the gear shift. I thought "Hang on, I don't remember this." But it was slight and I hoped it was my imagination. Well over the next few days I realized that not only was it NOT my imagination, but it was getting steadily worse.

Of course, I immediately went into trouble shooting mode. Ultimately I was stopped on the side of the road, with the car in neutral, carefully revving the motor. Sure enough, the vibration started up at about 2000 RPM. It was worse at about 2500 RPM, and then seemed to start abating, but it did not go away entirely. Since I was sitting still, that rules out the possibility that the imbalance lies in the transmission or beyond in the drive line or wheels. It is in the motor and clutch assembly.

I pushed the clutch in, held it and revved again, same thing. That test ruled out the clutch disk since it wasn't spinning with the motor at that point. The vibration was still present. That leads to the following conclusion. One of the following things has managed to fall out of balance: the motor, the flywheel or the clutch plate.

I find it hard to believe that a solid hunk of aluminum has somehow gone out of balance, so I think it's safe to rule out the flywheel. That leaves the motor or the clutch plate. Unfortunately, each of those seems as unlikely as the next, but there's no getting around the fact that one of them has gone out of balance.

So, what next? Well, I can't leave it this way. I noticed it getting worse in only 4 days and about 100 miles. There's no way it's going away. It will only get worse, do more damage and get more costly to fix. I'm going to have to pull the motor and transmission assembly, dis-assemble it and find out who the culprit is.

So there you have it. Hopefully I won't be out of commission too long. I had to drive my old ICE Passat this past weekend. I definitely miss the EV grin. Please feel free to leave your condolences.

Springs

2010-04-20T20:39:00.000-07:00

Well, it's become clear that I have to get new springs for the front end of the car. The other day I went over a speed bump and it bottomed out on the way down. Ouch.

I measured the ride height of the car before I started the project, and I also had it weighed (as you may remember). After the conversion was complete, I measured the ride height again and found that it was riding 3/4 of an inch lower than before. I started looking into different springs available for the car and found that they were all designed to lower the ride. Most by an inch or more. With that in mind, I was perfectly happy with the 3/4" I was seeing.

But then I started looking through the service manual and found out how BMW measures the ride height. It also listed what the ride height should be. I measured it the way they recommend and found that it was over 1.5 inches lower. Now my original measurement wasn't off, so that can only mean one thing, the car was already 3/4 of an inch lower than stock before I started. I haven't pulled the car apart yet to verify that there were already aftermarket springs on the struts, but that's my suspicion.

Oddly enough, the ride on the rear end of the car is at factory spec. Huh... strange.

Well any way, when it bottomed out the other day, I decided I need to do something about it. My neighbor had suggested looking at other BMW's to find out if there was a chassis that used the same spring with a different rating. Great idea! So, this is an E-36 chassis, and the good news is that there are several other models and years built on the E-36 chassis. The bad news is that there were only two heavier than mine, and they were only 100 lbs heavier. So, scrap that idea, that's not close enough to the 386 lbs the car gained.

I've read on the EV Discussion list that most any city has a place that specializes in building springs. Frequented by off-roaders and truckers, these places can take an existing spring and fabricate a replacement the same size but with a different rating. I asked my cousin Tommy (who is in the heavy truck business) if he knew of such a place. He said he didn't, but asked a local shop that sells springs. They had said they could send it out of state, but that they didn't know of a local place either.

So, I'll spend some time tapping into the off-road shops around town and see if they have a suggestion. If not, I guess I'll be sending my springs out of town. Of course, if the springs on the car are aftermarket springs, I'm going to have to get a hold of a stock one that I can send instead. That might be better because then I don't have to disable my car for the several weeks it will take to get the new ones.

Vacuum Issues

2010-04-16T07:59:00.000-07:00

While it's true that nature abhors a vacuum, nature has nothing on how much I abhor the vacuum brake system on the car. It turns an otherwise lovely quiet experience into a nerve shattering episode every time it kicks on. Part of that is my fault because I opted for pump I found on eBay for $90 instead of going for a quieter one from one of many EV component dealers. My efforts to deaden some of the noise it makes fell short.

But that's not what this post is about. I haven't posted much about this because I really haven't had a handle on what the issue was. Early on I noticed some erratic behavior from the system. It would refuse to come on, stay on too long, not turn off at all, turn off and I'd have no vacuum assist on the breaks or stay on and I'd lose vacuum assist with the brakes. I can tell you when that pump simply won't shut off, it sucks most all of the joy right out of my drive. As far as problems with that system are concerned, you name it and I've experienced it.

At first I thought that the vacuum pressure switch on the reservoir was bad, but ruled that out because I found a leak. I fixed the leak and the problem went away. Until one day the pump came on, pumped the system down and turned off and I found I had no vacuum assist. At that point, I was certain that the cause was a faulty check valve, so I ordered a couple replacements and some fittings to see if I could fix the problem. The check valve that came with the reservoir is kind of sloppy. It works, but you can suck a fair amount of air through it before it engages. As it turns out, that's really how it should work because a new one that allows for none of that play didn't work at all. It sealed off immediately and allowed no vacuum to the brake drum at all.

Well, after 4 more weeks and a number of episodes which I won't bore you with, I think I may have finally figured it out. I borrowed a hand held vacuum pump from a friend so that I could draw a vacuum on different parts of the system to see how things behave. I was hoping to find where the problem really is. I pulled into my driveway the other day and the pump was running non stop, and the brakes were working fine. I popped the hood thinking I'd pull the line out of the reservoir I installed that runs to the car's vacuum assist drum. I wanted to seal the canister with my finger to see if the pump drew a vacuum like it's supposed to and if the switch turned the pump off eventually. Well, I inadvertently flicked the vacuum pressure switch with my finger and the pump shut off.

Since then I've had the pump come on and refuse to come off on two occasions, only to find a quick tap on the switch causes it to trip and turn the pump on. After which it runs normally again. Now, I haven't ruled out a problem with car's brake assist drum, but this is certainly headway.

The switch has a screw that allows you to adjust the vacuum up or down depending your needs. I think I'll play with that a bit to see if it helps. If not, it looks like I'll be ordering a new switch. Eventually I want to replace the pump with a quieter one. They range in price from $250 to $400 for the real quiet ones. It's not the money at this point that's holding me back. It's the prospect of having to put the car back up on jack stands to incorporate the new pump into the existing system. It would require quite a bit of work. I guess I love driving it more than I hate the pump.

Visitors

2010-04-12T19:55:00.001-07:00

The last couple weeks have been pretty busy. I'm surprised at how many people have emailed after having seen the car on Jack Rickard's Friday video. So many positive comments and compliments. Why it's enough to give a guy a swelled head :-)

One of the first people to contact me was a local man by the name of Greg who has thought long and hard about converting a car. About three weeks prior to seeing the video, he'd come to the decision that the Z3 would be the car for him to convert. He was shocked to see a converted Z3 and floored that it was actually in the same town he lived in. Greg stopped over and I gave him a full tour of the car, answered all his questions as best I could and offered to help if he ever decides to try to pull it off. A great visit and I hope to stay in touch with him.

Today I was visited by one of the true stars in the EV world, and that was George Hamstra. George works for Netgain motors the makers of the WarP series motors and of course, the motor in my Z3. An icon in the EV motor world. He was in town with some friends enjoying the fantastic Spring weather here in Arizona, and took the opportunity to stop by and see the car.

What a great time. Lots of questions, laughs and pictures! I gave George and both his friends, Charlie and Terry, rides in the car and everyone had a great time. For Charlie and Terry, it was a first time for each of them in an EV. They were reluctant to go for a ride at first, just being polite I think, and trying not to imposed. But once I coaxed them into the car, they really enjoyed it. That's always the case with anyone who rides in an electric car for the first time. That's what the call the EV grin.

It's been a real pleasure answering peoples emails and showing off the car to people that take the time to come by. I expect that things will begin to slow down now that the car isn't getting any new exposure, and that's certainly ok. But for all you faithful readers, remember, if you're ever in Chandler, and you'd like to meet up and go for a ride, let me know. It's a great community and I'm happy to be a part of it.

Thank you all.

On A/C and RPMs

2010-04-02T09:19:00.000-07:00

On Monday I received the new beta exciter rings for the newer style RPM sensor. You may remember that the newer style RPM sensor mounts flush to the motor and would allow me to use the remaining portion of the tail shaft on the motor to mount a pulley I can use for the A/C system.

I got to work putting the new sensor in place so that I could run some tests and get some comparison numbers. I thought I'd get a new set of numbers using the old sensor first, and then switch the leads connected to the Zilla to the new sensor and test it. Last time I got readings in first gear at 10, 15, 20 and 25 mph. I wanted to do the same thing this time, but add tests in 2nd and 3rd just to get more data.

Sadly that wasn't to be. When I was putting on the new exciter ring, I knocked the cup for the old sensor that fits over the end of the tail shaft out of alignment, and didn't notice. When I went out to test, I watched the RPMs climb to about 1600 and then the tach went dead. When I got it back in the garage, I found that the magnet inside the cup had been rubbing on the side of the cup and self destructed. *Sigh*

So I took it off and started the test on the new sensor with the new ring to get some new data. Since I had the old data from the older style sensor, I could still compare those two sets. What I found was a slight deviation. At 25 mph, the old sensor reported 4300 RPM, but the new one reports 4600 RPM.

Working with the manufacturer and Ryan at EV Source, we decided to crunch some numbers to see what it really should be. Based on the size of the tires and the final drive ratio in 1st gear, the RPMs at 15 mph should be 2632. The sensor is reporting 2600. I'd say the new sensor is more accurate than the old one.

I took off the old assembly I'd built which was designed to hold both sensors in place, and mounted up the new one. Then I mounted the pulley. I don't have a belt for it yet, so I need to get that next. Then I need to take it down to an A/C shop and find out if they can build new lines for it, and more importantly, if they are willing to. I'm really worried they'll take one look under the hood and say "No way!" In any case, I'm one step closer to A/C.

So How Fast is This Thing?

2010-04-01T07:28:00.000-07:00

Most of you are aware of the difficulties I had with the car regarding acceleration early on, and how it was my own dang fault. And most of you are aware that problem has been sorted. Which probably means most of you are wondering when I'm going to post some 0 to 60 times and what not. Here's the full story.

Right now I have the Zilla set to only draw no more than 500 amps from the batteries. The batteries voltage is 160, so that works out to 80,000 Watts. Netgain recommends that you push no more than 170 volts to the motor, and as you probably know, the Zilla can put out a maximum of 1000 amps. That means that the most power I can theoretically send to the motor is 170,000 Watts. So, as the system is configured right now, I'm allowing just under half the power possible to go to the motor.

"Why" you ask? That's a good question for which I have a couple of lame reasons. First, the Link 10 meter I have can accurately read only 500 amps. If I pull more than that, it won't hurt the meter, it just won't read it accurately. So that's not really a problem as long as I don't put myself in a situation where I need to rely on the meter to determine how much energy I've drawn from the pack. I don't want to run the pack dead and destroy the batteries. Second is that I just want to spend some time breaking the batteries in under less than full stress conditions. I don't know if this is completely necessary, but I seem to remember reading somewhere that treating them kindly the first 75 cycles can add to their longevity.

The bottom line is that I do intend to ramp it up at some point in the future, just not yet. I likely wont' leave it there, but I'll do it just long enough to get some readings and have some fun. I was thinking mid April.

Right now the car does 0-40 faster than stock. It really sets you back in your seat. Above 40 though, the acceleration begins to fall off. It reaches 60 in about 10 to 12 seconds which is higher than the stock 7 seconds, but certainly acceptable for everyday use. I've reached 80 on the freeway, and the car was still pulling. I can easily spin the tires in first gear, and the tires chirp in a hard start from second. There's no question that there's a beast under the hood, it's just leashed at the moment.

A Video of the Car

2010-03-29T10:25:00.000-07:00

For those of you who aren't familiar with Jack Rickard from earlier posts, Jack is the fellow that encouraged me to change my plans from lead acid batteries to the lithium batteries. And while Jack had very convincing arguments for doing so, one of the biggest factors in the switch was the tremendous drop in price since I'd first looked at the price. From $21,000 down to $7,400.

In addition to help with the batteries, Jack has offered other sage advice. Well he went and posted a video of the car on his website as part of the weekly Friday show he does. It's a long one, well worth watching, and the EV Z3 is embedded somewhere in the middle.

Check it out when you get a chance!

Rolling Along

2010-03-25T19:41:00.000-07:00

Well, I've managed to clock nearly 400 miles on the Z3 since it's debut. Aside for the faulty controller setting (my fault), the only problem has been a faulty check valve on the vacuum system. However, at this point I'm not sure it was faulty, and I'm really not sure what caused the problem.

I replaced it with a new one and found I had the same problem. Clearly I need to figure out what's going on here. I removed the check valve and the brakes work, but the vacuum pump runs longer. The more that pump runs, the more I'm annoyed with it. It's by far the loudest thing on the car.

I took the car on the freeway the other day for the first time since I got the controller setting issues resolved. It pulled up to 70 with no problems at all. At one point, traffic started moving quicker, so I decided to keep up and see how it did. I got to 80 and there was still room in the pedal and the car was still pulling. I'd love to find out what the top speed is, but I don't have a safe, legal place to do it.

One thing that freeway speeds do is suck power. The car averages around 300 Watt/hours per mile on surface streets. But take it on the freeway and that jumps to about 410. I certainly don't mind using the power, but it illustrates just how much energy it takes to push through the air.

Today I took the car over to a local auto shop that's right around the corner from my house; they specialize in BMWs. When I first bought the car and told them what I planned to do with it, one of the guys there was kind of skeptical. He didn't say he doubted that I could pull it off, but it was clear he felt that way. Well I wanted to show him it was done, but he's left the company. When I told the others why I'd stopped by, they all wanted to see the car. So we went out in the parking lot and I gave them all a quick tour. After 20 minutes, several questions and numerous complements I headed off to run some errands. The car never fails to impress.

An Interesting Interview

2010-03-22T16:47:00.001-07:00

Shortly after I posted the car on the EV Album, I was contacted by one of the writers at Gearbox Magazine. They are interested in starting an EV portion to their online magazine and thought the Z3 would be a good car to start with. It seemed like a great idea to me, so I answered all the questions they had for me.

Here's a chance to read the article if you haven't already seen it. If the mood strikes you, post a comment. They're just starting this off and it would be good to leave them some feedback.

A Great Big Thanks!

2010-03-17T11:08:00.000-07:00

Now that the car is out of the garage and running the way it should, there's some people I'd really like to thank. Some offered a little support, some where instrumental in getting the car built.

Tim Millward - Tim did all the welding. I was absolutely at a loss without his skills. He was kind enough to drive the 50+ miles across town to work with me on several occasions. What a champ. Thanks Tim!

Ryan Bohm - Ryan is the proprietor of EV Source. I got most of my components through him and he offered terrific support. He was patient enough to answer each question I had regardless of how stupid they were. Anyone considering a vendor for EV parts could not choose a better source. Period.

Jack Rickard - Last summer Jack encouraged me to take the plunge and go for lithium batteries instead of lead acid. Boy am I glad I listened. The painstaking research that he's done on this type of battery has provided the practical knowledge that everyone in the EV world desperately needed. Theory is nice, but there is not substitute for empirical data! Check out his website when you have the time. Thank you kindly Jack!

Leonard Ellul Bonici - Len is (as far as we know) the only other person in the world to have converted a Z3. In fact, we started our conversions the same week. He finished his mid summer 2009 and has been driving it ever since. Len and I shared quite a bit of information with each other and he developed the solution we both use for the power steering proximity switch. Thanks again Len!

Josh Hardison - Josh is a friend of mine that took the time to answer all the questions I had about the fundamentals of electricity. I knew next to nothing when I started this. Josh filled in all the blanks for me.

Bill Catellier - My father Bill is one of the most mechanically adept people you could ever meet. Plus he knows a tremendous amount about electricity. He helped me refine all the design work and is one of the reasons the car turned out as well as it did.

Emily Catellier - My daughter Emily patently assisted me when ever I needed a spare hand or a gopher.

Mary Catellier - Last, but not least, my wife Mary. She thought I was crazy doing this, and she may be right. But she patiently stood by supporting me through the entire endeavor. Thanks sweety!

There were plenty of others that contributed here and there and I'm grateful to you all. I'm also grateful to all the readers of the blog (both of you). I enjoyed the whole experience.

I'll continue posting data and updates about the car as time goes by, so stay tuned!

Acceleration Problem Sorted

2010-03-16T16:44:00.000-07:00

Well, you can chalk this one up to a rookie mistake. There is a big difference between resting voltage in a battery pack and voltage under load. To keep the batteries safe, I want to keep them above 3.0 volts per cell. 3.0 x 48 = 144, so that's what I set the low voltage to. Well, they hit that when under load almost right away, which caused the Zilla to limit it's duty cycle to 25%.

Working with Ryan at EV Source, he recommended that I drop that to around 112 and see if that did it. Boy did it ever, I spun the tires quite easily.

I'll be posting more on the acceleration once I get the brakes working again. So stay tuned.

Sidelined

2010-03-13T13:48:00.000-08:00

Loyal readers (both of you) may remember that when I first started the car up, I reported some odd behavior from the vacuum pump. It wouldn't come on regularly and the brake pedal had an odd feel to it. At the time, the car was still up on the jack stands, so I couldn't tell if the brakes actually worked or not.

A few days ago, my father was driving the car and I noticed that the vacuum pump came on and was staying on for what seemed like a very long time. I asked him to pump the brakes, and within 15 seconds or so, the pump shut off.

Well today, I headed out of the garage with the aim of giving my wife Mary the opportunity to drive the car for the first time. As I pulled out, I noticed the vacuum pump running non stop like it had when my dad drove it. I pumped the brakes but found that they were getting no vacuum assist at all, and the pump still wouldn't turn off, so we had to scratch this outing.

I pulled the car back in the garage and started looking, tinkering and thinking. In short order, I realized what was causing this repeated problem, and with a few simple tests proved my hunch correct. The vacuum canister came with a check valve, and that check valve was sticking open. What that meant is the pump couldn't draw down a vacuum (which is why it ran non stop), consequently the brakes had no assist.

I've ordered a replacement valve and some other fittings to make the whole assembly from the vacuum canister to the brake assist drum a little cleaner. Until they arrive, no EV driving. :-(

Some Tests

2010-03-12T06:19:00.000-08:00

Though I haven't heard back from the distributor of the batteries yet about the discharge capacity, I feel safe in saying that my original belief was true. These batteries are capable of putting out the current I'm asking them to dump. A kind reader of the blog pointed me to a great page at EV Works that detailed some tests they performed on the Sky Energy and Thunder Sky batteries. The tests reveal many things, but key among them is the discharge potential. So at this point, I feel safe saying the batteries are not the issue.

I took some measurements on the HEPI pedal yesterday. There are 6 wires coming from the pedal. One is a 5 volt power (Red), one is ground (Black), and the others are signal wires. The voltage on the signal wires changes as the pedal is depressed. Here's what I found.

In the up, or "not depressed" position
Red - 4.94 V
Green - 1.58 V
White - 4.94 V
Orange - .792 V

Fully depressed position
Red - 4.94 V
Green - 4.83 V
White - 4.94 V
Orange - 4.33 V

It would seem that the White wire is also just providing power. Truthfully, I don't know if the differences in these readings has any significance, but I find it interesting that neither the Green nor Orange wire come up to the full 4.94 Volts when depressed. But even more interesting is the fact that the Green and Orange wire don't match. My understanding is that the pedal has two sensors in it for redundancy. I would think that would mean the voltage they put out should match, but that's just an assumption. I'll be sending this data off to the distributor I bought the pedal from to ask for help and assistance.

The Zilla controller has the ability to put out a stream of data for diagnostic acquisition or DAQ. All the data is displayed in Hex format, at the rate of 10 lines per second. I connected my MacBook to the Zilla, set everything up and then captured some data during a full, pedal to the floor, acceleration. Once I had the data, I imported it into a spread sheet and converted all the Hex to decimal. What I found backed up what I was experiencing. Under full acceleration the current across the motor's armature peaked at 150 amps.

So, what did we learn from all this? I think all I really learned was that the Zilla is indeed sending a fraction of the current to the motor that it's capable of. And it re-enforces my previous beliefs that it's either the pedal, or the Zilla. Now that I have some data, it's time to get the manufacturers and distributors involved.

By the way, thanks to all that have been offering help and advice! It's truly appreciated.

More Data

2010-03-11T07:25:00.000-08:00

So far, I've put nearly 300 miles on the car. Everything has been working, more or less, perfectly. So lets have a look at the data.

I'm averaging about 330 Watt/Hours per mile. I've seen averages as high as 394 and as low as 288. That's leaving me a 50 mile range. What I can tell you from this is that the manner in which I drive makes a big difference. But there's a bit more too that story.

The meter shows that the car is drawing 0.2 amps when it's off. That seems pretty reasonable, after all the Zilla draws a small amount of current, as does the Link 10 meter, and the DC to DC converters are always pushing 13.2 volts to the 12 volt system. However, I've no idea if something on the original 12 side is leeching power from that. What I have found though is that if the car sits for 12 hours unattended, it will draw off something like 500 Watt/hours. Hmmm.... I need to find out what's happening there. So the higher numbers I'm seeing in the Watts/mile adventure above are a bit skewed because some of those have a power vampire worked in.

No improvement on the acceleration issue, but I do have some more information. I've noticed that under full acceleration the meter shows I'm drawing no more than 200 amps from the batteries. Well, that certainly lines up with what I'm seeing. 200 amps fed to a WarP 11 motor will produce about 40 ft/lbs of torque. The question is, why not the full 500 I've set? Again, I'm left with one of three things. The Zilla simply isn't drawing the higher current because of a fault in manufacturing or an incorrect setting. I don't think that's it. The hepa pedal isn't sending the proper signal to the Zilla, or the Zilla isn't interpreting that signal as a 100% "throttle on" signal. That seems just as unlikely. Last, the batteries can't release that kind of current. According to the manufacturer's spec, they should be able to release 480 amps for 20 seconds straight. And event higher discharge current for even shorter periods of time.

That leaves me sort of scratching my head. I need to test each independently. I've reached out to the various distributors that I worked with for assistance, so I'll keep you posted there.

I had the car weighed yesterday. I found that through all this, the car has gained a total of ... drum roll please.... 386 lbs. That's about 136 lbs more than I'd thought, but really not bad. So, the car weighs in at 3,285 lbs. The ride height at the back hasn't changed, but on the front of the car it's 1/2 inch lower than stock. Considering that new spring kits for the car, designed to lower the ride height will take 1 inch of the height, I don't think I'm going to worry too much about it. Still just to be safe, I intend to ask a few mechanics. The really cool thing is that I've managed to maintain the same weight distribution, front to back, that BMW had. I've got 52% front and 48% back. Not bad.

Here's a great story. I wanted to have the car reclassified as an EV because the registration fees are a fraction of a regular car. I called the ADOT, our DMV. When it was all said and done, I spoke with 5 people and got 5 different answers as to how I should do it. The one reliable one, as it turns out, was from the fellas down at the only state owned emissions testing place. He told me that ANY emissions testing place can certify it, but often won't because they don't know how. "Which is silly," he said "because all you have to do is look and see there's no engine or gas thank. Done!" He said if they wouldn't do it, I'd have to bring it to him which is about 15 miles away. No worries.

I went to the testing station 2 miles from my house and asked the guys there. They were completely dumbfounded. Completely! One guy said, "Well, we just check that the gas cap fits and plug the car into the computer." So I asked him "And when you find there's no gas cap or gas tank... And when you find the ECU says there's no engine?" Again, blank stares. I said "Look, you're supposed to have a form that you can certify and hand to me that says the car has no engine, and instead has a bunch of batteries." Blank stares.

So, when I pulled into the testing station 15 miles away, and told them what I needed, the guy laughed and said "They wouldn't do it huh?" He was the same guy I spoke to on the phone. He told me this wasn't the first time he's seen this by any means, or the most ridiculous case either. One of the stations in the west valley sent a Tesla owner down to their station to have it certified as an EV. "For-christ-sake!" he said, "That thing was manufactured as an EV. What's wrong with these guys!?" I'm sure I don't know. But I think it will all change soon with all the EVs that are supposed to hit the market soon.

Real World Data: The Good, the Bad, and the Ugly...

2010-03-04T13:58:00.001-08:00

The Good

I've been driving the car for three days now, trouble free. Everything works as designed. The vacuum pump for the brakes kicks on every second or third time I press the brake pedal. The speedometer and tachometer work properly. The heater works brilliantly, getting the cabin toasty warm in a very short time.

The car is very quiet. When sitting still, the only thing heard is the fan blowing air into the motor. As I mentioned above, the vacuum pump kicks on once in a while and it makes quite a racket, but nothing compared to the traffic noise around me. When I turn the car and the power steering pump comes on, there's a high pitched whirring sound, but it can only be heard when there's absolutely no traffic noise.

The power steering system is working quite well. It takes a bit of getting used to in that the first 3 inches I move the wheel, it's a bit stiff, but once the pump kicks on, it's easy as it was before I removed the engine. This can make for a bit of a jerky turn unless you're prepared for the sudden drop in resistance. It won't take long to get used to it. The good news is that I can change lanes at speed easily and the pump never comes on, which means I did a good job positioning the proximity switch.

So far I've put 62.5 miles on the car. With the local price of gas at $2.75 and figuring in cost of maintenance on an internal combustion engine, I've saved $6.10 so far. It costs just under $.03 per mile to drive.

The Bad

A couple days ago I mentioned a noise coming from the power steering rack on full turns. While it's still there, it seems to have diminished quite a bit. Not sure why, but I'll have to looked into that.

The Link10 meter is still a bit of a mystery to me. While it measures and displays the voltage quite nicely, the other measurements are either wrong or confusing. Because it's designed for battery packs under 50 Volts, I had to install a voltage pre-scaler. That means a voltage of 161.0 reads as 16.10. OK, that's no big deal. As expected, it's scaled everything else as well. Again, not a bad thing, but I need to learn how to read it. The kWh dial showed that I'd used 0.53 after my last trip. Based on the time it took to recharge the car, and the amount of current the charger draws, I'd think it took about 6.25 kWh to charge it up. If I'm dealing with the same decimal point error then that means the 0.53 translates to 5.3 kWh. That's about 15% higher than the 6.25, some of which undoubtedly is lost in efficiency converting AC to DC. Still it's impossible for me to know for sure because I don't have a meter that allows me to measure the current going in accurately. I may need to do something about that.

The most inaccurate thing the Link 10 displays is its "fuel gauge". If I really used 5.3 kWh (which I think is accurate), the "fuel gauge" showed that I was empty. I'd set it up to allow me to use about 16 kWh before it would display empty. So that aspect of the dial is worthless for now.

That brings us to range. Most everything I'd come across in my research lead me to believe I could expect to use between 225 and 275 Wh/mile. In reality, I'm using about 380 Wh/mile. That translates to a straight reduction in range. Now instead of the 60 to 65 I had calculated, I'm looking at more like 42. Not ideal, but I can certainly live with that. Now that's maintaining a 20% reserve in the batteries to protect their longevity, so the full range is closer to 53. Over time I may be able to increase that a bit here and there, but for now it looks like I'll be staying within 20 miles of home.

I haven't had the car weighed yet, but the front end is riding 1 inch lower than stock. Next week, I'll have it weighed so I can compare and decide what to do about the suspension.

The Ugly

Well, there's no getting around it. The car is slow. It accelerates like a 90 horse power economy car. I can't for the life of me figure out why that's the case. The controller is set to allow a full 1000 amps to the motor, which should produce enough torque to spin the tires! Instead, if I floor it from a stand still, it accelerates like a weighed down golf cart.

I've checked and I don't seem to be dragging an anchor, so I'm really not sure what's going on. I know it's not a friction problem. The car roles forever. If I simply let off the throttle pedal while doing 45, it will coast for over a quarter mile losing less than 5 miles an hour. It's like putting a regular car in neutral. I've gone over the Zilla's configuration again and again, but it's OK.

Now, I do have the controller set so that it can draw no more than 500 amps from the batteries. I did this for two reasons; first the Link 10 meter's shunt is a 500 amp shunt which means that if there's more than 500 amps going through it, the Link 10 can't read it leading to further inaccuracies in the meter's data. The second reason is the fuse I have on the battery pack is only good for 400 amps sustained. It will tolerate 1000, but not for more than something like 10 seconds. Still, throwing caution to the wind, I tried setting the battery current up to 1000 to see what would happen. I started the car gave it some juice and found that it was only slightly better than before. Not enough of a difference to warrant getting a bigger fuse and leaving it that way.

So there you have it, good news and bad. I'm going to continue looking into the problems I've encountered, and hopefully I'll find something. I think I'm going to have to ask a few experts some questions. Stay tuned.

The EV Z3 is on the Road!

2010-03-02T16:01:00.000-08:00

I pulled the car out of the garage today, washed it down and started running it through the neighborhood for some tests.

The car isn't as quick as I'd hoped. In fact it's slower than it was with the original engine, which is quite strange. The motor should be putting out far more torque than the engine could. I'm not sure what's going on, but I'll be investigating it.

So far everything is working quite well, but later in the day I noticed some noise coming from the power steering rack when I made a hard left. I'm thinking that the seals in the rack may be going, so that's another thing to investigate.

While I was hoping to drive it out of the garage and be done with all the work, it's clear that I'm going to be fiddling with it a bit more over the next few weeks and months. I guess you had to know that was going to be the case :)