13,000 EV Miles

No doubt the 2 or 3 people that read this blog have long lost interest since I haven't posted anything for 3 1/2 months.  But as they say, no news is good news, and I would say that by and large, that applies here.  I pulled into the garage yesterday after running a quick errand (a Frosty for a sick child), and I took note of the odometer reading.  I delivered the Frosty and then entered the data in my spreadsheet and was surprised to see that the running total of EV miles I've driven added up to exactly 13,000.  Now the 3 year anniversary of the car hitting the road is in a month and 1/2 or so, but this seemed noteworthy enough that I thought I'd post an update of how things are going and include some numbers for those who enjoy statistics.

Keen readers will remember the episode I went through, just about a year ago, with a high voltage leak to the chassis, which I traced back to a frame leak through the motor and ultimately resulted in getting a new motor from Netgain.  George Hamstra was simply sick of repairing it and sending it back to me.  On a side note, George told me he has that motor in his garage and intends to put it in his Bricklin conversion.  I hope it does well for him.  At any rate, in addition to putting the new motor in, George also sent me some new brushes to try out, ones he felt would produce less carbon dust and so were better suited for my application.  He sent me (at his expense mind you) some Helwig Red Top brushes that are made of a harder compound than the standard brushes the Netgain motors come with.

You have to understand, Netgain Motors was born out of the EV drag racing community.  The earlier drag racers kept burning up their GE motors.  George and others saw different opportunities to improve the motors here and there.  They were working with Warfield Electric on building motors that incorporated their changes.  Before long they had a completely new beast on their hands and decided to start selling them.  The brushes they chose were of a softer carbon compound, ideal for pushing high current to the armature   Under drag racing conditions, the motor would generally fail for some other reason long before the brushes did.  But under low current applications, like driving to the store for milk and such, the brushes tended to wear out much faster and give off a lot of carbon dust.  The Helwig brushes have worked out so well for them that they've made them available on new motors.

Understanding that, we get back to my car and the unexpected change I noticed after I installed the new motor with the new Helwig brushes.  Suddenly, the car was more efficient.  About 14% more efficient to be precise.  Jack Rickard of EVTV ran experiments with an old WarP 9 motor he had at his shop, and found the same improvement.  Well, a great deal of time has passed, and I've put many more miles on the car, 4797 to be precise.  I thought I'd take a look at the numbers to see if the increase in efficiency has held true.  The thing is, I realized that I'd been doing the math wrong.  Well, the truth is, I knew I was doing it wrong, but I was too lazy to fix it, thinking the difference would be minimal.  To sum up, I was taking all the trips I made, and averaging the Watt hours per mile used.  The trouble is, the 275 Watt hours per mile used on a 35 mile trip was being averaged equally with the 378 Watt hours per mile on a 4 mile trip.  Anyone can see, those numbers needed to be weighted differently since the distance was different.  The solution is easy: add up all the miles driven and divide it by the sum of kilowatt/hours used.

What did we get?  As I mentioned, I've driven 4797 miles since the brush replacement, and I've used a total of 1526.46 Kilowatt/hours.  That works out to 318 Watt hours per mile.  In comparison, I grabbed a 4804 mile sample of data from before the brush swap and noted that I'd used 1779.72 Kilowatt/hours, which works out to 370 Watt hours per mile.  So does the 14% efficiency gain still hold water?  370 - 14%(51.8) = 318.2.  Apparently so.  I knew the way I was calculating the data before wasn't going to be wildly inaccurate, or even mildly for that matter.  But it's encouraging to see that numbers still hold to be true.

Moving on.  A couple weeks ago I plugged the car in, turned on the charger and heard a familiar "pop" come from the front of the car.  I recognized it immediately as the same "pop" I'd heard before when the motor had become caked with carbon dust and there was a mini flash over in the motor.  What the...?!!!  The only way this would happen was if the carbon dust given off by the brushes wasn't being blown out.  Since the Manzanita charger is grounded to the chassis, when you turn on the charger, if it senses a path from the chassis to the battery pack, it will either throw the circuit breaker in the charger itself, or blow up.  I've had it do both.  For the gory details of each, feel free to look further back in the blog.  Suffice it to say, you don't want to accidentally touch a battery terminal and the chassis with a multi-meter probe at the same time when you're charging.  Anyway, clearly I had a build up of carbon again!  How could this happen?  I've got a fan forcing air into the motor for chrissake! It should be blowing all that dust out.

I checked the fan, and it was running, but the output was very low.  I looked at the filter and found that it was caked with dirt.  Ahhhh.  I'd cleaned it about 6 months earlier, but clearly there's a problem.  Well the problem is really quite simple.  Having no way to locate the fan and the filter higher up in the motor compartment, I mounted it on a tray right next to the motor.  Meaning that the fan and the filter are about 9" off the ground, right were the dirtiest air is.  You may have noticed that every manufacturer locates the air intake for their cars as high up in the engine compartment as possible.  I'm thinking that may be intentional.  I took the filter off and the flow of air was much better, like I expected it to be.

So now I'm left with two problems.  First, the motor is full of dust and I need to blow it out. Second, I need to figure out what to do about this filter location; clearly where it's at is not the best place for it.  Last time I had a dust problem with the motor, I used compressed air to blow it out.  That worked pretty well as a huge plume of dust came out when I aimed the air gun into it.  The problem is, I have to take the motor's shroud off, and to do that I have to take out the batteries over the motor and to do that I have to ...  you get the picture.  Curse the idiot that designed this!!!  But then I had a flash of inspiration.  What If I simply hook up my leaf blower to the inlet hose, the one that runs from the fan to the motor.  Leaf blowers put out a crazy amount of air.  Oh, now this will be good.  Or at least fun.

It wasn't easy, but I was able to get to the inlet hose and basically taped the end of my leaf blower to it using my favorite tape in the world, gaffer's tape.  It's basically black duct tape, but easier to tear.  I had my daughter sit in the car and rev the motor up to about 3500 RPM, and I turned the blower on.  I was very pleased to see a plume of black dust come out the back of the motor (and also a bit disturbed).  I let it run this way for three or four minutes until I was confident it had expelled all the free carbon it could.  The great thing was, I could put my hand at the back of the motor and feel a tremendous volume of air coming out.  I started to wonder, could I some how use this leaf blower as my motor fan?  Apart from it being impractical, it would make the Z3 the noisiest EV on the road, ever.  No, what I really need to do is sort out the filter location problem.

With the fan located low like it was, it's collecting dust at a much faster rate, and ultimately choking the motor.  I looked, thought, measured, looked, thought some more and came up with nothing.  There is simply nowhere else to locate that filter.  Then I had a thought.  what if I eliminated the filter completely?  Stick with me for a moment.  The Netgain motors come with a screen covering the front bell housing, and the brushes.  People run them like this all the time.  The problem is some dirt and sand will inevitably get in and get on the armature and brushes cause them to wear prematurely.  OK, so that's the trade off.  But now, what if the inlet for that air came from a place that was less prone to see dirt and sand in the first place?  After all, the front of the motor sits right where you would expect most of the dust and grime to be, so if I could find a place for the inlet that would provide cleaner air than that, I should be good.  What I found was that there was a way to run a 3" hose from the fan inlet up in front of the firewall and just behind the large battery pack that's over the motor.  It's shielded from the main airflow when the car is moving down the road, yet it's got an open area large enough that it can easily get all the air it needs.  I checked and the output of the fan was terrific.  As far as I'm concerned, problem solved.  It's true that a bit of dirt may be blown into the motor, but I think this is a far better solution than cleaning the filter weekly to ensure good airflow through the motor.

The truth is, I'd love to get a fan that would push more air into the motor.  The one I have pushes 120 CFM.  George even said that's likely too low.  The problem again is one of space.  The fans I've found that push more air won't fit in the space I have.  I keep an open eye out for one, from time to time I comb through the interwebs looking for a suitable candidate.  So far, no luck.

That's all for now, but check back in early March on the car's 3rd anniversary as I'll post some more stats.

10,000 Electric Miles

I pulled into the garage last night and noted the amp/hours I'd used and the mileage on the odometer so that I could record them like I do every time I charge the car.  The mileage read 144,214 which is significant because that marks exactly 10,000 miles since the Z3 was reborn as an EV.  I figured that this would be a good time to go over some of the numbers I've been collecting that last 2 years, 4 months and see what I could glean, and then share them with you. 

530        Number of Charge Cycles

18.9       Mean average miles driven between each charge
34.9%    Mean average depth of discharge
36.0%    Median average depth of discharge (half the data points are above, half below 36.0)


WARNING: Wild numbers and speculation will now commence. 

CALB says that these batteries are good for 2000 cycles at an 80% Depth of Discharge (DOD), and 3000 at 70%.  But how long will they last if I'm averaging roughly 35% DOD?  Of course no one knows.  However, if you use the 50% increase we see going from 80% DOD to 70% DOD as a baseline, and extrapolate that out, we might be able to conclude that we could get 4500 cycles at 60% DOD.  If we keep going and then apply it to my average DOD of ~35%, we come up with something close to 12,500 cycles.  At 18.9 miles per cycle, that works out to 236,250 miles. 

Of course that's all theoretical, but it's likely not too far off from reality.  But let's be conservative and say I only get half that number of cycles out of the batteries, that's still 118,000 miles.  However, we need to keep in mind that the original 2000 and 3000 cycles that CALB states is a bit misleading.  It's not as if the batteries stop working when they get to 2000 cycles.  What they really mean is that after 2000 cycles to 80% DOD, the battery will only hold 80% of it's original capacity, so they will still push the car as far as I need to drive on a daily basis.

</Wild numbers and speculation>

As you can see this whole "cycle life" or "life expectancy" question for the batteries is highly fluid with the real numbers determined by a number of factors all at once which are, for practical purposes, impossible to determine or track.  One thing that is certain is that these batteries will out perform a lead acid pack by at least an order of magnitude.  Seeing as they only cost 4 times as much as a lead acid pack, I call that a good bargain.  And that's not even taking into account the numerous other benefits they offer, like the 60 mile range vs. a lead acid packs 20 miles (at best). 

$1,402    Amount saved not buying gas
3639       Total number of kWhs used to charge the car

That $1,402 figure is derived by taking into account the price of gas when I charged the car and subtracting the cost of the electricity used to charge the car.  I always charge the car at off peak hours, and I add an extra 10% to the amount of electricity consumed to take into account the inefficiencies of the charger as it converts the 240 Volts AC to 160 Volts DC. 

So how has the car performed?  How well has it used that energy?

376        Mean average Watt-hours consumed per mile
388        Mean avg Watt-hours/mile with the old solid brushes
319        Mean avg Watt-hours/mile with the new split brushes

You can see there's been a marked difference in efficiency since replacing the brushes.  The old average of 388 Watt-hours per mile was experienced over 442 charge cycles and 8,184 miles.  The average has dropped to 319, and that has been over 88 charge cycles and 1,816 miles.  I don't know how one could dispute the claim that these Helwig Carbon split Red Top brushes are better. 

That increase in efficiency has moved the car from a 50 mile range using the 388 Watt-hours per mile figure to 61 miles using 319 Watt-hours per mile.  Of course most of you know how much range can fluctuate with an EV depending on how and where you drive.  I've been on 40 mile trips with the car where I saw the energy consumption average drop to 266 Watt-hours per mile, which works out to 73 mile range.  Is that useful data?  I don't know, but it's interesting.

Expanding on that, I found 4 data points that fit together nicely.   These are individual trips with the miles driven, the total kWhs used and the Watt-hours used per mile.

50 miles      17.23 kWhs    345 Watt-hours/mile
51 miles      17.89 kWhs    351 Watt-hours/mile
51 miles      16.49 kWhs    323 Watt-hours/mile
51 miles      14.57 kWhs    286 Watt-hours/mile

Guess which trip occurred after the new brushes were installed in the motor.  By the way, those were all trips to the same destination and back.

The real question at this point is how are the batteries fairing?  For those not familiar with the car and reluctant to go back and read the multitude of tedious posts, I bottom balanced the pack back in February of 2011.  The only way to find out how the batteries are doing now is to draw the pack back down to the bottom and make note of the amp/hours taken out and the state of charge on each battery.  Hmm... sounds like another post.  Stay tuned.

Efficiency I Can't Quite Explain

With the exception of the few months the Z3 has been off the road for repairs or upgrades, I've been driving the car for just over 26 months.  During that time, I've kept detailed records of every charge/discharge cycle of the batteries.  Every time I plug in, I note the mileage on the odometer, and the number of amp hours I've drawn out of the pack.  I then take that data and plug it into a spreadsheet that calculates a number of things for me, including how much money I've saved because I wasn't burning gas, how much the electricity I'm using is costing me, and most interestingly, how many Watt-hours per mile the car is using.

I've reported in the past the the car averages about 320 Watt-hours per mile on surface streets.  That's the number I've used to calculate the range of the car: 19,400 Wh / 320 Wh = 60.625.  This is why I've always stated the car has a 60 mile range.  And I've proved that out once, driving 62 miles on a charge once, in preparation for doing a bottom balance on the batteries.

Of course, once I go on the freeway traveling between 65 and 70 mph, that 320 Watt-hours per mile begins to look like a distant dream.  The aerodynamic drag on the car causes energy consumption to quickly rise to around 420 Watt-hours per mile at 65 miles an hour.  That meant that my round trip to work, a 23 mile journey, which includes 7 miles of surface streets and 16 miles of freeway, averaged between 370 and 380 Watt-hours per mile.  I've made this trip a few hundred times, I know the numbers.

It's no secret that I've had a few problems with the motor in the car.  The balancing putty has come off for a some inexplicable reason, twice.  Just recently it developed a short to the case that no amount of air blown through its guts could resolve.  George Hamstra at Netgain has been a champion through all of this and ultimately had a new motor sent to me.  In addition, we swapped out the brushes from the standard H-49 brushes used for high current applications like drag racing, to H-60 brushes which are better suited for street use.  A cool feature on Helwig H-60 brushes is the split, Red Top design, which helps to ensure better contact on the commutator.

At any rate, I got the new brushes seated in the motor properly, put the car back together and launched it back onto the streets about 3 weeks ago.  The car is my daily driver, so once I began driving it to work and other places, and recording the energy consumption, I was a bit surprised to notice it was more efficient.  At first I thought it was maybe just an anomaly, but it's clear something has caused the car to make much better use of the energy in the batteries.  My round trips to work are now averaging about 280 Watt-hours per mile.  Compare that to the older 370!  That's more than a 25% improvement in efficiency!  I made one trip where the average dropped to 266.

Today I took a bit of a longer trip out to Scottsdale.  A total of 38 miles, with 30 of those miles on the freeway, traveling around 70 mph.  The average consumption for the entire trip was 274 Watt-hours per mile.  In the past, I would have estimated this trip to be a 400+ Watt-hour per mile trip.  But that's not all!  During the entire trip, I had the AC system on (which draws about 9 amps) and of course, I've configured the power steering pump to run all the time now adding another 2 amp continuous draw.  BTW, the change to the power steering is interesting, but that's another post.  So there are more parasitic loads, yet, efficiency is up.

The one thing I haven't done yet is to see what average I would get if I traveled at 40 or 45 mph.   There's no reason to think the gain in efficiency that I'm seeing wouldn't appear there as well, but I simply don't have those numbers yet.

It seems like an obvious conclusion to draw that the increase in efficiency can be attributed to the new motor, or brushes, or a combination of them both.  But I really can't say that with certainty.  Perhaps I'd made some error when installing the drive line in the past which caused some binding or friction that I simply wasn't aware of.  I kind of doubt that, but who knows?  There's no question I've gotten better at disassembling the drive line of the car, but there really isn't much room for error here.  I have no reason to doubt the numbers the meter is giving me; after all, it's the same meeter with the same set up I was using before the motor swap.

What ever the cause, the car does seem to be more efficient.  At an average draw of 280 Watt-hours per mile, it's gone from a 60 mile range to nearly a 70 mile range.  I'll take it.

Update 5/20/2012:

I've continued to see the gains in efficiency I detailed above, but I've realized I've let myself fall victim to insidious creature that is over optimism.  I've always maintained that the Z3 had a 60 mile range.  That was based on the fact that it consumed about 320 - 330 Watt-hours per mile when driving at ~45 mph in normal traffic.  What I really hadn't done is take an average over multiple trips to get a more balanced number, a real world number you can take to the bank.  Well since I've seen this improvement in efficiency, I've gone back  to my spreadsheet to see if I could mine some more useful, accurate data from the numbers.  Here's how it works out...

Since the car was put on the road, up until the motor/brush replacement, it has averaged 376 Watt hours per mile.  That is the real world average.  Sure there were many trips that were better, but there were also many that were worse.  I can't get out of my neighborhood without consuming something like 480 Watt-hours per mile.  It's all about stopping and starting.  With no regenerative braking, stop signs and stop lights really affect your range.  The more of them per mile, the worse your range.  Well, there's 6 stop signs on one of the routes it takes to get from my house to the main streets, so you can imagine what that does to energy consumption.

The average after the motor/brush swap has dropped to 321 Watt-hours per mile.  Compare that to the old 376, and you note a 14.7% improvement.  That is huge!  Interestingly, and I've mentioned this above, virtually all of the trips I've made in the car since putting it back on the road have been on the freeway at 65 - 70 mph.  Meaning, that as more trips on surface streets are recorded I expect that 321 number to drop even further.

The bottom line is that I've been misrepresenting what the car's range really is by skewing the data toward the happier, more optimistic lower numbers.  Not intentionally or maliciously mind you.  The old average was 51.6, the average now seems to be 60.4.  A painful thing to admit, but there you have it.  Just as I could have easily squeezed 60 miles out of the car before, sticking to surface streets and avoiding stops, I expect I could squeeze 70 miles out of it now, doing the same. 

I've brought all this to Jack Rickard's attention at EVTV, and just like me, he was skeptical and ultimately amazed.  He's been doing some tests swapping out the original H49 brushes for the split, Red Top H60's and he's finding the same results.  I have a feeling this is going to be a hot topic in the EV community for a while.

What An Ordeal

The few of you who read this blog have probably wondered what's been going on with the Z3.  When I last left you, I'd received the new motor, had put the new split top, harder brushes in and was seating them by running the motor off of a 12V battery.  Well, quite a lot has happened, and frankly, it wasn't all good.  So sit back and enjoy the saga.

Once I installed the new brushes and turned the motor on, it made a hell of a racket for the first few hours.  I remember seeing a video John Allen had made when he was breaking in new brushes for his Warp 9, and I was struck by how loud it was, so I wasn't too surprised when mine made similar noises.  I ran the motor for 100 hours and at the end, it sounded as smooth as silk.  Job done!

I mounted the motor up to the transmission and tightened up all the bolts and called it a day, planning to reinstall the motor/transmission back into the car the next day.  During the night, I realized I'd done something kind of stupid.  The manual for the car states that you should put a little grease on the input shaft before you mate it up to the motor.  It already had a film of grease on it, but I thought more is better.  When thinking about it that evening, I realized that I had cleaned off a little grease I'd found on the flywheel.  It was in a pattern that looked like it had been thrown off the shaft.  It was at that point I realized more is not better, and I'd set myself up for a greasy, slip prone clutch.  So I took the tranny off the motor, cleaned the shaft of excess grease and mounted it back up.  It only took 45 minutes or so, so it wasn't that bad.  I'm telling this story so that if anyone out there reading this can learn a lesson from my stupidity, then I've served some purpose on this planet.

Moving on.  The motor/transmission assembly went in to the car later that day without a hitch, and thanks to my dad who came out to help me.  I mounted up the drive line and started the process of re-assembling the car.  It went quite smooth really.   I was making one of the last battery connections when I leaned my elbow on the chassis, and it felt like I got stabbed or cut.  I remember thinking that I didn't remember the bolt I leaned on being particularly sharp.  I touched it again and realized that I didn't get stabbed, I got shocked.  That's right my friends, the leak, which I was trying to get rid of, the one for which I'd been sent a replacement motor, was not gone.

Talk about a kick in the teeth.  I started testing and dis-assembling everything and came to the conclusion that, once again, the source of the leak was in the motor.  How could this be?!!!   I was absolutely gutted and just walked away from the car for what ended up being the whole weekend while I thought about what to do.

I decided what I had to do was figure out, definitively if it was the motor or something else.  I decided the best way to do that was to assemble all of the components completely, but leave the motor out of the assembly process.  In place of the motor, I simply ran a cable from the Motor + terminal on the controller to the Motor - terminal.  This was simply to replicate the existence of "something" in the system at that position in the circuit.  Once it was all back together (minus a few batteries) I found that there was no leak. I added the motor back in, the leak appeared.

I thought perhaps breaking the brushes in had created enough dust to cause the problem, so I decided to blow it out with compressed air.  While some dust did come out, I could still measure the HV pack voltage on the chassis.  Ghaaaa!!

It was time to contact George again.  I can't express to you how much I did not want to darken his inbox with bad news again.  George asked if I would send him and Tom Brunka of Helwig Carbon Brushes a picture of one of the brushes that I broke in.  He wanted a close up of the face and shot of the profile.  Puzzled, and unsure of how that would help, I obliged and sent off the photos.  Tom got back and said that the brushes looked like they were broken in perfectly, so that was good.  But then he apparently noticed something else, and that was the model number printed on the brush indicated it was for a 9" motor.

The pieces started falling into place for George at that point.  The commutator on a 9" motor has a smaller circumference than that of an 11" motor.  That means that the brushes for a 9" motor would be made with a smaller arc to the face.  Aside for that, they are identical in function, composition and structure.  But what that meant was that rather than the brush's surface resting with more or less complete contact on the commutator, it was riding on the very edges.  That explained why they were so loud when I first put them in.  Truthfully, at that time, I even wondered if I might have been sent brushes for a 9" motor, but it was just a passing thought.

So, through an innocent mistake, George had sent me the wrong brushes.  He mentioned that it really was no problem to use them now that they were seated so well, and I would have had to wait another 2 weeks to get 11" brushes anyway.  I was fine with keeping these.  Anyway, because the brushes weren't contoured correctly for the 11" motor, that meant that a bit more material had to wear off of them than would have normally happened.  Couple that with the fact that when running off a 12V battery, the motor doesn't spin fast enough to create enough airflow to vent the dust that does come off the brushes, and you have a recipe for developing and internal path to ground.

I went back and measured the resistance of the path from the motor terminal to the chassis and found that it was .880 mega Ohms.  Don't ask me why I didn't measure that after I blew the motor out the first time, but I didn't think to.  I saw that I could measure voltage on the chassis and felt that was enough of a problem that I didn't think to measure resistance.  But what I found was that after I had blown it out, it had made a difference.  .880 mega Ohms can only pass 0.13 milliamps at 160 volts.  I could touch the terminal of the battery and the chassis and felt nothing.

George added that once I got the motor back on the road and spun it up to 3000 RPM, it would blow the rest of that dust out.  he also mentioned that Warfield Electric consider a leak to chassis acceptable as long as it won't light up a light bulb.  Well, .13 milliamps isn't enough to light a light bulb, and it's also not enough to cause my charger to complain.

Today I got everything back together, tested the systems, and flipped the charger on with fingers crossed.  It came right on and dutifully charged the batteries back up to full.  All systems go!  I took the car down from the jack stands drove it out of the garage and put 20 miles on it this afternoon.  It seemed like everyday since the car has been out of commission, I came across either a Nissan Leaf, or a Chevy Volt, while out driving and I would just grumble in envy.  Today I saw Leaf  while I was driving the Z3, and I simply felt joy.

Seating New Brushes

You're probably familiar with the problem I've been facing recently regarding the leak to chassis ground through the motor.  It's proven to be a very strange problem. I made a quick video to demonstrate what I'm seeing, take a look.

A leak at 635 Ohms and 160 volts equates to 252 milliamps.  The 436 Ohms I read the following day would produce a current leak of 367 milliamps.  I've seen the reading as high as 1180 Ohms, and as low as 350 Ohms.  This sort of leak is most often caused by the accumulation of dust in the motor.  I've blown enough air through the motor that if that were indeed the problem, it should have fixed it.  But as you all know it hasn't, so George Hamstra has decided he's seen me suffer enough at the hands of this motor, so he's sent me a new one.

 Since that picture was taken, I've pulled the clutch assembly, flywheel, adaptor plate and taper-lock hub assembly off the old motor with the help of my friend Dave from Tucson.  However, I haven't put it on the new motor yet.  In email exchanges with George, I mentioned that I would be sending back the $320 brushes he sent me (at his expense) to try to resolve the problem with the original motor.  But he replied saying instead that I should put them in the new motor.  He believed that the brushes in the new motor were likely brushes better suited for racing.  I peered in the motor and found they were the Helwig Redtop brushes, but when I compared them to the ones George had sent me I could see a marked difference.  They were a bit shorter, but much darker in color.

So at George's recommendation, I swapped them out.  But that means I need to seat, or bed in the new brushes before I put the motor in the car.  Essentially, you strap the motor down, and connect it to a 12v battery and let it spin for 100+ hours.  It sounds easy enough, but actually getting it done required some effort.

First I needed a 12 battery.  I don't have one laying around, so I went to the local Costco and bought the cheapest 12v deep cycle battery they had for about $80.  I was under the impression that the motor would draw about 3 to 5 amps, once it had spun up and was running smoothly.  So I thought my little 0-12 amp battery charger could keep up.  Well, that was off by a factor of 10.  It actually draws about 45 amps at start up and settles in to a constant draw of about 35 amps.  Fortunately a friend at work was kind enough to lend me his heavy duty charger that can put out up to 200 amps for starting a car, or as much as 40 amps for charging the battery.  Perfect!  Here's how the assembly looks.

At the top right, we have Fred's big charger.  Below and to the right, is the 12V battery.  I have both the cables to the motor hooked up to it, as well as the cables from the charger.  Notice on the negative line running to the motor is a big switch; a nice way of turning the motor on and off.  My meter is sitting on top of the battery with the probes connected to the terminals.  In the morning, I turn the motor on.  When I see the battery hit about 11.00 volts, I turn the charger on.  It operates by timer, so I set it for 2 hours.   It immediately pushes the voltage up to about 12.8 and puts out about 43 amps.  The motor is drawing about 35, so it's a net of about 8 amps going to the battery.  Over that two hours time, the voltage on the battery rises to about 13.5.  By the time the battery hits 13.7, the charger is putting about about 36 amps, or one amp more than the motor draws.  So I turn the charger off and let it rest.  (I don't want to burn it up.)  When the battery gets back down to 11V, the charger goes back on.  I'm on day 4 of the break in, and it's been running about 50 hours.  Since the charger is on a timer, I can't run the system at night.

When the brushes have had enough time to seat, I'll re-assemble the adaptor plate and clutch, then work to getting it back in the car.

A Great Video 

On an unrelated note, a PBS station back East, WSIU, has published a story about last Septembers EVCCON and EVTV.  The story is quite well done.  It explains what the movement is about, why people are doing it for themselves and why Jack and Brian are producing the weekly EVTV show.  It's about 1/2 hour long, and it's well worth watching.  While the Z3 is not featured in the video, you can see it in the background on a few shots.  Take a look: