Acceleration Problem Sorted

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.

Some Tests

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.

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

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.

Testing the RPM Sensors

Today, I downloaded and set up a program that John Lussmyer wrote called ZillaConfig. It's essentially a desktop application that connects to the Zilla controller and provides you with a desktop window for configuration. It's really pretty slick. If you interested, you can get it here.

But perhaps the neatest thing it does is allow you real time graph of the Zilla's output while the car is running. You can watch motor current, throttle position and lots of other things, including RPM. So, with the ZillaConfig program loaded up and running on my laptop, I set off for testing.

Loyal readers (both of you) will remember that I installed both sensors on the car a few weeks ago; however, I could only wire one up to the Zilla at a time. So first up was the older style sensor that sits on the end of the tail shaft.

I decided the best way to test would be to put the car in first gear and spin the wheels up to 10 MPH, then 15, 20 and 25, taking RPM readings at each point. Simple enough. I ran the test on the old sensor, and then swapped the leads to the Zilla and re-ran the test with the newer sensor. Here are the results:

Old Sensor
10 MPH = 1600 RPM
15 MPH = 2500 RPM
20 MPH = 3400 RPM
25 MPH = 4300 RPM

Huh, I just noticed that there's a 900 RPM difference between each entry. Anyway, here are the results of the second, or newer style sensor:

New Sensor
10 MPH = 2500 RPM
15 MPH = 3700 RPM
20 MPH = 5000 RPM
25 MPH = -

The Zilla wouldn't let me over 5000 RPM, so I couldn't get to 25 MPH. Clearly, the two sensors are not sending the same signal to the controller. Bad news for me. I need to use an RPM sensor to protect the motor from over spinning it, so doing without really isn't an option. But if the only one I can use is the older one, that means the end of the tail shaft is occupied by the sensor. That in turn means that there is no room for the pulley that I need to use to drive the A/C system. In short, old RPM sensor equals a very hot summer in the Z3.

There are a couple rays of hope on the horizon. First, the supplier that I got the sensor from is working with the manufacturer to find out what can be done, if anything, to make it work. Second, I could have a piece machined that would screw into the tail shaft and extend it by an inch or so. While not optimal, that would work.

Before I run off and have that piece made, I need to go to an A/C shop and have them look at the car and determine if it's even feasible to run the lines needed in the very cramped spot the compressor sits in. Of course I can't do that until the car is out of the garage. That tachometer can't come soon enough!

Odds & Ends Part XI

Let's start with a list of things I did today...

• Installed high voltage (HV) fuse
• Ran +HV line from trunk to fuse
• Ran +HV line from fuse to breaker
• Ran -HV line from trunk to forward batteries
• Ran -HV line from shunt to controller
  
• Ran +HV line from breaker to contactor
• Re-routed signal wires away from HV cables
  
• Attached all signal wires for the Link10 monitor
• Attached throttle control wires to the Zilla controller
• Attached the RPM sensor wires to the Zilla
• Connected the hairball (Zilla's brain) to the Zilla controller
• Attached wires for heater to the battery
• Attached charger to the battery

Here's a shot of the breaker and the shunt to the right and above it. As I was running all the wires to those two, I realized that there was no safe way to get all those wires in place while the batteries on the right side of the picture were in place. So, I had to disassemble the pack in that box to get that work done.

Here's a shot of the fuse I installed today. That fuse can easily handle the 1000 amps I could draw from the battery pack. But it would blow quickly in the event of a dead short.


Here's the zilla controller at the bottom of the frame, and the hairball at the top. I think I've got all the components wired to it at this point. In fact, I think I'm ready to test the system and see if I can spin the wheels. But before I do, I think I'll go over the wiring of each item, just to make sure I haven't made any bone-headed mistakes.

RPM Sensor Mount

Yesterday I finished fabricating the mount for the two RPM sensors. Regular readers will remember that the older style sensor is guaranteed to work with the Zilla controller, but it interferes with my ability to use the tail shaft of the motor to run the A/C compressor. The newer one will allow me to use the tail shaft, but has never been tried with the Zilla. I'm going to find out if it will work.

This is a side shot of the motor's tail shaft with the RPM sensors attached. On the right hand side, closest to the motor you can see the sensor with the wires protruding toward the camera. that ring just in front of it is the exciter ring mounted on the shaft of the motor. You can see that the rest of the shaft would be free if the second, older style sensor were not mounted over the end of the shaft, which you can see on the left. It has a little black cup (which you can see) mounted over a magnet (which you can't see) that is screwed onto the end of the tail shaft. The whole point of having both mounted at the same time is so that once I get the motor spinning, I can simply swap which leads are attached to the controller and monitor the output from each.

The controller expects four pulses per revolution, which each sensor can do. I don't expect there will be a problem with either, but I'm really hoping the newer style one works, or it's no A/C for me!

I must have an RPM sensor on the motor. The motor's red line is 5500 RPM. It will tolerate higher speeds for short times, but not for sustained periods. The danger is that the all the copper in the motor will unwind off of the armature, thus destroying the motor. The controller has a feature that will allow me to set a red line that the controller simply won't pass. Of course I have to be careful and not drop the car in the wrong gear and over spin the motor. You can also set the controller so that it limits the RPM to a much lower number when the car is in reverse. That should be handy. But one of the coolest features is called Valet mode. All I have to do is press a button (yet to be installed) and it tells the controller to put it in Valet mode. I can set that up so that the controller limits current and RPM of the motor. Essentially keeping someone who isn't used to the car (a valet, mechanic, or teenager) from taking off like a nut.

After I finished that I got to work on the large battery box up front. I managed to get the brackets made and half the batteries installed and fastened down.

That was exceedingly difficult, the spaces are very tight. Notice that gap between the top of the battery on the right hand side and the bracket? I'll be shimming that somehow. You'll also notice that the terminals on the batteries are facing each other, which probably alarms the more astute readers. If they were to touch... It's kind of like crossing the streams. you don't want to allow that to happen. Well the brackets won't allow them to move closer than they are toward each other. But to be certain, I'll be placing some non conductive material between them just to be sure.

Today I had planned on finishing the battery installation on this box, but it looks like that's going to have to wait. I'm under doctor's orders not to lift anything heavy for two weeks. *Sigh* The other day I pinched a nerve in my neck and lost all feeling in my left arm. I can assure you that was a bit scary. But all is well. The Dr. has put me on anti-inflammatory medication and want's me to take it easy for two weeks. I'm sure lifting one battery at a time isn't a problem, but wrestling with stacks of 4 is probably not wise. I think progress will slow for a while. I'm going to see how much other stuff I can get done in the mean time.

Installing Batteries Part I

I've fallen a bit behind in posting what's going on, so let's catch up. I gotta warn you, this one's a bit long.

The copper straps, or interconnects, for the batteries arrived Wednesday. The suppliers found some in their warehouse after all, so they didn't have to come from China. They are composed of 5 strips of copper, held together with head shrink tubing and are a total of 3/32" thick.

I fit most of the batteries in the back box in the trunk, 12 across, with room above for up to 9 more. With all those batteries in there, it would be a very tight fit and almost impossible to route any sort of cooling air flow around them. I only need to fit 18 in that space, so I decided I'd better start playing with the spacing to help promote better air flow. Rather than 12 across in the back row, I decided to go with 11 and space them a bit. But since the interconnects are made to fit properly when the batteries are snug against each other, that meant I was going to have to make my own. I already had some 1/32" copper strap, so I simply cut, laminated and drilled a few that are about 1 centimeter longer than the others.


You can see I'd put one in place just to test the spacing. Once I fit the rest of the straps, there will be about 4 mm between each battery. Plenty of space for air flow. Above, there will be 7 more, two stacks of 2 and one of three at the far right side. In the midst of the 11 batteries I'll be putting a temperature switch that will turn the fan on when the temperature reaches 122 °F. Although I don't have any of it built yet, I know just how I'll be anchoring all those batteries to the box and the chassis so they don't fly around. Oh, and notice the larger black wire laying across the batteries at the bottom of the picture? That's for the XM Radio tuner that I've installed in the back. Gotta have music!

Today I spent time building out part of the system that will allow me to anchor the batteries in the larger tray that will go under the hood.


The strap in the middle of the box is bolted to the tray underneath. All of the rest of the bolts go through the box, through the tray and into the supports that my friend Tim and I welded to the chassis this last summer. The whole thing is as sturdy as a rock. This box will hold a total of 14 batteries (138 lbs for those of you keeping score). There will be two stacks of 4 laid flat in the front (bottom of the picture), and two stacks of 3 in the back. I had planned to stack 4 in the back as well, but I ran into a snag. One of those snags where if I had to build the car again, I would know to look out for it.

When Tim and I welded those supports to the frame, I specified more clearance over the motor than I needed. Only 3/4", but it turned out that I could have used that space. You can't see it in the picture, but when you close the hood, the two nozzles for the windshield wiper fluid come down right into the back corners of the boxes. They would interfere with closing the hood, but only just. How tight you ask? 1/4". That 3/4" clearance I left seems pretty silly now. It's not that big a deal, it just means 18 batteries in the back instead of 16.

Before I mount the two smaller boxes in front of the large one, I need to sort out two things. One is the rpm sensor mount and the other is the A/C compressor. The mount for the rpm sensor will be easy enough, but there's more to the story. Since there isn't enough room in the engine compartment to run the A/C compressor off of an auxiliary motor, I have to run it off the tail shaft of the main drive motor. I had purchased a rpm sensor that mounts to the end of the tail shaft, but if the pulley is in place it interferes with the sensor. It was beginning to look like I would have to choose one of the other.

Along came a new sensor that is designed specifically for the WarP motor I'm using. It mounts flush to the motor and I could use it and the pulley at the same time. The only problem is that no one is sure if it will work with the Zilla controller. The controller expects 4 pulses per revolution and this sensor can deliver that, but only testing it will tell for certain. So the bottom line is that I have to build a mount for the first sensor and test it out, and then mount the new one and test it to see if the Zilla interprets them the same. That will be part of the testing that I'll be doing before the car comes off the jack stands.

Either way, I need to have the compressor's mount built and ready to go in case I can use it. Other wise, I'd have to disassemble the battery boxes I would have installed by that point so that I could work in the space. Taking the compressor out if I can't use it, while the batteries are in place won't be difficult.

Speaking of the compressor, I'd been sweating one detail, and that was how to hook it up to the electrical system. There are three wires on it. Take a look...

Notice the big black harness at the top. That contains one wire, and the matching harness is on the car, so no problem there. But take a look at the side there, and you'll see two wires, one with a male the other with a female plug. There is no place to plug those in. No dangling wires left in the engine bay that might accept those to plugs. Baffled, I went to talk to the guys that took the engine out. They showed me that those two just plug into each other. Josh, the mechanic had a car on the lift and showed me. I'll be damned. I would have never thought that they'd build a compressor with an external wire that has a connector in it. The only reason I can guess for that is if you needed to pull it apart to do diagnostics on the unit.

Anyway, thanks to them, I've got all the wiring sorted for the A/C system. Now if I can just get it in the car, with a functioning rpm sensor...

The Controller

After finishing work on the primary 12 volt system last week, I decided this week that I would start getting the controller mounted into the chassis and start connecting all the wires to it that it requires. The Zilla controller will sit in the electrics bay above the platform that holds all the 12 volt relays and other bits. It means that once the controller is in place, I can't easily get to the 12 volt tray below it. That is certainly not ideal, but with the limited space I have, it was unfortunately necessary. The fact is that all of the components mounted on that tray are not the sort of things that should fail. There's certainly no fuses down there.

That's the Zilla controller, with the hairball above it. All the high voltage lines run to the controller, and all the control wires run to the hairball. There's a RJ-45 connector on both the controller and the hairball, and it came with a cable that runs between the two. My guess is that the hairball does all the calculations and feeds the signal to the controller which simply spits out the appropriate amount of current to the motor.

You may notice that I moved the main contactor (that white cylinder toward the top right corner of the frame). It had been located in the lower right frame, but it became clear that running the 2/0 cable to the controller with the contactor in the old position wasn't going to be very easy. I think it will work out much better in this location.

I also spent some time trying to figure out if I will be able to make the stock tachometer work with the Zilla. The Zilla can drive a standard tachometer for a 4 or 6 cylinder car. The problem I face is that the signal that was sent to this tachometer was clearly sent via the CAN bus in a format that I have no way of determining. The tachometer itself has 4 pins that plug into a circuit board right behind the instrument.

On a normal aftermarket tachometer, those four wires would be laid out like this:
1 - to the coil or alternator
2 - 12 volt positive
3 - chassis ground
4 - 12 volt for the instrument's light.

On the stock tach, I was able to measure one pin at 8.5 volts, a second at .56 volts and the other two had no voltage. Nor did they have continuity to ground. Uh huh. Well, it's likely that there was some sort of signal sent down one of those two wires that shows no voltage, but which wire, and what that signal was, I have no idea. It could have been a 12 volt pulse. It could have been a pulse that tied the instrument to ground. No way to tell. I'm likely going to have to replace it with an after market one. But before I do, I'll experiment with it a bit. I might get it to work, I might get it to send off some funny smelling blue smoke. Either way it will be fun.

Oh, and still no word on the batteries. Curses!

Ignition Switch

The Zilla controller requires two leads from the ignition switch. One that has power when the key is turned to the "Start" position, and the other when the key is in the "Run" position. Today, I thought I'd look into isolating each lead and running an attached line to the electrics bay.

The "Start" position lead was easy to locate. I spliced a new 18 gauge wire to it and ran that to where the Zilla will sit. For whatever reason, the "Run" position lead was much harder to locate. So much so, I haven't found it.

The ignition switch has 4 positions, Off, Accessory, Run and Start. There are 6 lines running to the back of the switch. One of the lines gets power when ever the car has been started, and power is sent to it even after you turn the car off. Only pulling the key removes power to that line. I certainly don't want the car to run until I pull the key out. None of the other leads change state when you move the key through the positions. Now, granted, I've been testing this with a simple continuity test using the power feed and the other lines. I'm thinking that I'm just going to have to wait until I can run power to the switch and measure voltage across each terminal.

I also ran power out to the switch in the fuel door. You may remember that switch will keep the car from starting up when the fuel door is open and the car is charging. That's it for today. Two more things checked off the list.

The Last of the Mechanical Stuff

It's a late post today; it's been a busy day. Let's see...

I built the support for the tray that will hold the Zilla and the Hairball, and mounted it in place. Looking at the space, it's clear that some of the electrical stuff will have to be placed under that tray. There simply isn't enough room on top. So I laid it all out on the garage floor, trying to pick the items that were likely to need any attention after install. Apart from a failure of any one component, I think I'm set. There is one thing I'm going to have to do, and that's to sort out what the remaining wires from the cars electrical system do. There aren't many, but I need to track them down. Bleh, not looking forward to that.

I took off the power steering line that ran from the old pump to the steering rack. I took several careful measurements and soon will be taking the old tube and the new pump down to a shop that can custom fabricate a new line. I'm dreading how much that's going to cost.

Spent some time cutting and fitting some duct work for the fan that will blow fresh air into the back battery box. It will be controlled by a thermal switch in the box.

With the completion of the power steering pump, and then mounting up the A/C compressor, there will be no more major mechanical things left to do. At that point, it will be just sorting out the electrical stuff. The truth is, what remains for the A/C and the power steering are pretty minimal, so I'll be setting those aside until I have all the parts. That means I'll be starting all the electrical work in earnest tomorrow.

The Charger and a Home for the Zilla

I finished installing the charger in the electrics box in the trunk. I connected the charger to the power line that comes in from the gas door, and mounted the charger itself to the floor of the box. I also mounted the DC to DC converters in the box, simply bolting them down into place, and I sealed the perimeter of the box where it meets the chassis, to be sure that any water that splashes up can't get in the trunk area.



I still need to finish up the wiring on the for the converters and connect the charger to the batteries, but as I don't have them yet, that will have to wait. One of the things you can't see is a port in the back of the box that will vent fresh air into the compartment. When the car is running, or when the charger is on, a fan will kick on to force fresh air into the box, helping to keep everything cool. I also need secure that wire loom to the top of the box and eventually cut the carpet that was there to accommodate the opening.

I mentioned yesterday that I'll be using the original location that was used for the car's electronics as the home for the Zilla and anything else I can squeeze in there. Here's a shot of that space complete with an aluminum sheet I cut to fit.


That sheet will act as a tray that I can mount the Zilla and the hairball to. I still need to build the support for the sheet, it will sit a little higher than where it is in the photo. I'm a bit concerned I'm going to run out of room for all of the electrical doodads that I need to install. Some of them I can put under the tray because I won't need to access them unless they fail. Others I may end up running into the cabin and mount under the dashboard. I'll just have to play it by ear.

Never Say it's Done

Last Friday I mounted, for what I thought was the last time, the aluminum tray under the motor. Well, over the weekend, I realized that with a few modifications I could improve the way it fits into the chassis. It nagged at me all weekend until I could bear it no more. Today it came out. Again. I made the modifications, wrestled with it again and finally got it back into place. While I'm not saying that it's permanent, I did put thread lock on all the bolts that hold the cross brace that it sits on into place.


I mounted the water pump as well. Not that exciting or time consuming, but one more step closer. Notice the nice brass housing.


I also permanently mounted (doh! there I go again) the back box that will house the charger and DC to DC converters. Next I'll be mounting all the components in them. I can't begin too much of the wiring at this point, but I'll do what I can before the batteries arrive.

I also sorted out how to mount the Zilla controller. There is a nifty little water tight area back near the firewall, right in front of where the passenger sits. It held the car's ECU and many other electrical connections. Most of those are gone now. I'm going to have to build a little tray to hold the controller and the hairball, but there's plenty of room, some good places to anchor the tray and it shouldn't take too much work.