Posts
Work continues on the Clubman. Actually the work is going quite well. The Video work I'm getting a little behind on. I did just post the video for removal of the Exhaust system and the fuel system. This talks a bit about our battery box placement as well and the SAE J1772 plug we hope to have from Yazaki before the project is completed.
I also got edited down and posted the video on front drive shaft removal. This provides a step-by-step on removal of the front right drive shaft. I rather failed to mention you need to remove the front left drive shaft as well. It is essentially identical except it does NOT have the engine brace that has to be removed on the front right.
We installed two battery boxes yesterday under the rear seats. These are 18x13 inch boxes each designed to hold three "batteries" of four cells. As the Blue Sky cells are 67 millimeters thick rather than the 61 mm of the Thundersky's, and as we still have NOT received these batteries that were supposed to be here July 1, I'm guessing a bit. But I think they'll fit. The Thundersky winds up being about 11.25 inches for four cells and the end plates. I've assumed 12.25 inches for the Blue Sky's.
The rear seat boxes went in very nicely. Brain installed a 1x1x20.5 inch 12 gage brace between the rear suspension member and the cross member at the front of the rear seats. The boxes went in and he bolted them to the cross member with some 1 inch angle iron. You could stand in the result and the boxes came out beautifully. The original gas tank straps went right back into place, and we JUST cleared the emergency brake cables. Actually, the cables are stretched to the limit around the boxes, but it still seems to work ok.
If the rest of the boxes come out this well, I'm going to be a very happy camper. We will have a second box resting on top of the cross members defining the rear seat area and this box will hold 12 batteries of 4 cells each. That is quite a box - about 360 pounds.
We were a little daunted by the concept that if we needed to reach the lower batteries in the rear seat area, we would have to remove ALL of the 12 batteries in the box on top of it, as well as the box itself. That seems like a lot of work. Brain has located a set of rails used on railroad locomotives for batteries. They are rated for 1000 pounds and work kind of like a desk drawer. His plan is to mount the big battery box on these rails, and it will slide aft into the cargo compartment, revealing the lower batteries underneath. That would be terribly cool. We'd have to empty the cargo area of course to operate it, but taking the dry cleaning into the house would be a lot easier than disconnecting and removing 12 batteries. If he can pull it off, this will be a conversion deluxe.
We'll have an additional 7 batteries and two Brusa chargers (I hope) in a box mounted where the spare tire is now. I haven't got this totally worked out but am working toward a 32x22 inch box - the 22 being the problem. I think by narrowing the box from 35 to 32, I can get enough extra room between the trailing links of the rear suspension to pull this off. I REALLY need 22 inches here if we are to include the two Brusa NLG513s in the spare tire box.
Jack
Wednesday, July 29, 2009
Sunday, July 19, 2009
Transmissions
Somebody wake me up. This cannot be. It just cannot be.
One of the reported problems with the BMW Mini-E is that apparently MOST of the vehicles have a problem with the transmission just magically kicking into NEUTRAL while going down the road - even while accelerating. A lot of the owners are returning the cars for service on this issue, and reports are that the technicians are not only not expressing surprise, but actually seem familiar with the problem and can fix it rather readily.
Hooray.
I'm still stuck on the NEUTRAL part. How does the transmission kick into NEUTRAL? Well I watched one users video. And I watched it again. And what I saw just floored me. PRND. You've GOT to be kidding me.
Do NOT tell me, (actually if anyone can confirm this, please DO tell me) that they coupled an AC induction motor to an AUTOMATIC TRANSMISSION????
It simply cannot be. But it DOES explain another problem reported by owners. Apparently, there is a significant delay when starting out between pressing the accelerator and actually departing. It is reported to be sufficiently significant to be both annoying and potentially dangerous. And the explanation I read questioned why they would program this into the controller. It doesn't appear while you are going down the road, just when taking off.
It can't be.
An automatic transmission operates on hydraulic pressure in the torque converter. This is not only quite inefficient, but it poses a real problem to us electric drive types. You see a gasoline engine idles at the stop light. ANd it turns sufficient RPM to maintain the hydraulic pressure in the torque converter. An electric car does NOT idle at the stoplight. It just sits there. The shaft is quite still.
So one explanation might be that they did actually use an automatic transmission . ANd made no provisions for an external pump to maintain pressure. Without one, the pressure falls, and when you do finally put on an accelerator pedal, there will be a DELAY while the torque converter spins up to pressure. This would be very annoying.
There are two solutions to this. One is to tap into the transmission and add on an external hydraulic pump that runs all the time. That's not very eifficient, but it solves the problem.
The other is a litttle tricky, you have to modify the controller/inverter to spin the shaft at low rpm even with no accelerator input. This is quite wasteful, but really doesnt take much power. ANd it would keep the torque converter under pressure.
The obvious solution is not to deal with it at all. VERY FEW car conversions are done with automatic transmissions. People converting automatic transmission cars mostly pull the entire rig and try to drive the differential directly with an electric motor. The problem with this is you need a much more powerful motor to take off, and usually they wind up increasing the gear ratios in the differential to at least 5:1 to do this.
With the front wheel drive, this really isn't an option on the Mini automatic transmission. But it begs the question WHO DRIVES AN AUTOMATIC MINI anyway. It goes against the entire ethos of the car. And they have one of the best six speeds in the world with the Getrag 6 transmission that normally comes in the mini anyway!
This transmission is just a work of art. It has THREE overdrive gears, yet remains very tight and close, shifts like a dream, and makes this little economy car drive like a Porsche. It is just SUPERB. I don't see the point in a sub compact economy car with an automatic transmission, but you can get one strangely enough. But I almost refuse to believe they mated an AC induction motor to an automatic transmission.
If so, great news. If they can get 100 miles, we can get 110 with the Getrag 6.
We have actually removed the engine and transmission from the car. We sent the motor and transmission to VAC MOTORSPORTS in Philadelphia to be mated. This is actually a BMW racing shop with full CNC machine shop that is going to do several things for us. First, they are going to device a bell housing adapter to allow us to bolt the motor to the Getrag. Second, they are going to work some sort of shaft in to mate the female involuted spline shaft of this strange motor to the flywheel. Third, they are going to install a lightweight aluminum flywheel. And finally, they are going to install a Quaif automatic torque biasing differential in the transmission.
This should give us a SUPERB drivetrain. After driving the stock Getrag, and examining it on removal, I would rate this piece of equipment AN ENGINEERING MARVEL. By installing a lightweight aluminum flywheel and Quaif differential, we will have brought it up to full track specs.
With all this going for it, that BMW would put an AUTOMATIC in the MINI-E is just not believable. Somebody tell me I'm wrong. But it WOULD explain the delay on takeoff that users are experiencing. And I DID see PRND in the video.
Jack Rickard
One of the reported problems with the BMW Mini-E is that apparently MOST of the vehicles have a problem with the transmission just magically kicking into NEUTRAL while going down the road - even while accelerating. A lot of the owners are returning the cars for service on this issue, and reports are that the technicians are not only not expressing surprise, but actually seem familiar with the problem and can fix it rather readily.
Hooray.
I'm still stuck on the NEUTRAL part. How does the transmission kick into NEUTRAL? Well I watched one users video. And I watched it again. And what I saw just floored me. PRND. You've GOT to be kidding me.
Do NOT tell me, (actually if anyone can confirm this, please DO tell me) that they coupled an AC induction motor to an AUTOMATIC TRANSMISSION????
It simply cannot be. But it DOES explain another problem reported by owners. Apparently, there is a significant delay when starting out between pressing the accelerator and actually departing. It is reported to be sufficiently significant to be both annoying and potentially dangerous. And the explanation I read questioned why they would program this into the controller. It doesn't appear while you are going down the road, just when taking off.
It can't be.
An automatic transmission operates on hydraulic pressure in the torque converter. This is not only quite inefficient, but it poses a real problem to us electric drive types. You see a gasoline engine idles at the stop light. ANd it turns sufficient RPM to maintain the hydraulic pressure in the torque converter. An electric car does NOT idle at the stoplight. It just sits there. The shaft is quite still.
So one explanation might be that they did actually use an automatic transmission . ANd made no provisions for an external pump to maintain pressure. Without one, the pressure falls, and when you do finally put on an accelerator pedal, there will be a DELAY while the torque converter spins up to pressure. This would be very annoying.
There are two solutions to this. One is to tap into the transmission and add on an external hydraulic pump that runs all the time. That's not very eifficient, but it solves the problem.
The other is a litttle tricky, you have to modify the controller/inverter to spin the shaft at low rpm even with no accelerator input. This is quite wasteful, but really doesnt take much power. ANd it would keep the torque converter under pressure.
The obvious solution is not to deal with it at all. VERY FEW car conversions are done with automatic transmissions. People converting automatic transmission cars mostly pull the entire rig and try to drive the differential directly with an electric motor. The problem with this is you need a much more powerful motor to take off, and usually they wind up increasing the gear ratios in the differential to at least 5:1 to do this.
With the front wheel drive, this really isn't an option on the Mini automatic transmission. But it begs the question WHO DRIVES AN AUTOMATIC MINI anyway. It goes against the entire ethos of the car. And they have one of the best six speeds in the world with the Getrag 6 transmission that normally comes in the mini anyway!
This transmission is just a work of art. It has THREE overdrive gears, yet remains very tight and close, shifts like a dream, and makes this little economy car drive like a Porsche. It is just SUPERB. I don't see the point in a sub compact economy car with an automatic transmission, but you can get one strangely enough. But I almost refuse to believe they mated an AC induction motor to an automatic transmission.
If so, great news. If they can get 100 miles, we can get 110 with the Getrag 6.
We have actually removed the engine and transmission from the car. We sent the motor and transmission to VAC MOTORSPORTS in Philadelphia to be mated. This is actually a BMW racing shop with full CNC machine shop that is going to do several things for us. First, they are going to device a bell housing adapter to allow us to bolt the motor to the Getrag. Second, they are going to work some sort of shaft in to mate the female involuted spline shaft of this strange motor to the flywheel. Third, they are going to install a lightweight aluminum flywheel. And finally, they are going to install a Quaif automatic torque biasing differential in the transmission.
This should give us a SUPERB drivetrain. After driving the stock Getrag, and examining it on removal, I would rate this piece of equipment AN ENGINEERING MARVEL. By installing a lightweight aluminum flywheel and Quaif differential, we will have brought it up to full track specs.
With all this going for it, that BMW would put an AUTOMATIC in the MINI-E is just not believable. Somebody tell me I'm wrong. But it WOULD explain the delay on takeoff that users are experiencing. And I DID see PRND in the video.
Jack Rickard
Regenerative Braking
The AC induction motor and controller give us the option of employing "regenerative braking". This concept derives from the fact that there really isn't much difference between a motor and a generator. If you apply voltage to the motor, the shaft turns. On the other hand, if you turn the shaft, voltage comes out.
The BMW Mini-E does employ regenerative braking. And by all reports, it is a nightmare. It kicks in when you remove your foot from the accelerator. And it pretty much throws you forward into the seatbelts when it does so. Nobody likes it.
The problem is twofold. First, when you quit using the motor as a motor, and use it to convert the forward motion of the vehicle to electricity to recharge the batteries, it is actually quite controllable. By altering the excitation to the motor, you change how much power it will put out, and that is a function of how much power is available at the shaft. What this means is that you set it up so that it slowly decreases the speed of the vehicle, or really QUICKLY decreases speed, electronically. They provided NO adjustment for the driver. Assuming that would be too techie, they just hardwired it full on. So as soon as you take your foot off the accelerator, it goes into full power regen, and the car speed plunges. It's just LIKE putting on a brake hard.
The solution is pretty simple. We'll tie our regen to the brake light signal. In this way, you don't get regen until you put your foot on the brake. This makes sense, braking should come from the BRAKE not the accelerator. The brake lights come on at the lightest touch, so by just feathering the brake pedal, you'll be able to kick in regen without putting much brake into the game.
The second solution is to give the driver the control. We'll have a small knob/potentiometer where you can dial in just the amount of regen you want. On a long steep downhill, you might want to crank it up and get some juice out of it. In normal flat city driving, you might want to dial it all the way down and not deal with it. And at all times, you should quickly learn where it feels most comfortable for you.
This opens another pretty touchy opportunity. The Mini has power assisted brakes that work off of engine vacuum. We don't have engine vacuum. So we are going to have to install a small vacuum pump. The problem is not installing it, and they aren't terribly expensive. But they are annoyingly noisy.
We have opted for a unit from EVcomponents that features an oil filled muffler and is supposed to be ultraquiet at $375. Any $100 automotive vacuum assist pump will actually do but they are noisy.
But we have a target of opportunity here. It may well be that we won't want to use this pump at all. With regen on the brake light switch, we may find that regen offers sufficient braking, and we actually WANT the real brakes to only come in with dramatic pressure on the brake pedal. I suspect we don't need the vac boost AT ALL. The problem is, we won't know until the car is pretty much completed.
So we are going to install it, but have a switch to turn it off or on. You may not need one at all. We'll see.
Jack Rickard
The BMW Mini-E does employ regenerative braking. And by all reports, it is a nightmare. It kicks in when you remove your foot from the accelerator. And it pretty much throws you forward into the seatbelts when it does so. Nobody likes it.
The problem is twofold. First, when you quit using the motor as a motor, and use it to convert the forward motion of the vehicle to electricity to recharge the batteries, it is actually quite controllable. By altering the excitation to the motor, you change how much power it will put out, and that is a function of how much power is available at the shaft. What this means is that you set it up so that it slowly decreases the speed of the vehicle, or really QUICKLY decreases speed, electronically. They provided NO adjustment for the driver. Assuming that would be too techie, they just hardwired it full on. So as soon as you take your foot off the accelerator, it goes into full power regen, and the car speed plunges. It's just LIKE putting on a brake hard.
The solution is pretty simple. We'll tie our regen to the brake light signal. In this way, you don't get regen until you put your foot on the brake. This makes sense, braking should come from the BRAKE not the accelerator. The brake lights come on at the lightest touch, so by just feathering the brake pedal, you'll be able to kick in regen without putting much brake into the game.
The second solution is to give the driver the control. We'll have a small knob/potentiometer where you can dial in just the amount of regen you want. On a long steep downhill, you might want to crank it up and get some juice out of it. In normal flat city driving, you might want to dial it all the way down and not deal with it. And at all times, you should quickly learn where it feels most comfortable for you.
This opens another pretty touchy opportunity. The Mini has power assisted brakes that work off of engine vacuum. We don't have engine vacuum. So we are going to have to install a small vacuum pump. The problem is not installing it, and they aren't terribly expensive. But they are annoyingly noisy.
We have opted for a unit from EVcomponents that features an oil filled muffler and is supposed to be ultraquiet at $375. Any $100 automotive vacuum assist pump will actually do but they are noisy.
But we have a target of opportunity here. It may well be that we won't want to use this pump at all. With regen on the brake light switch, we may find that regen offers sufficient braking, and we actually WANT the real brakes to only come in with dramatic pressure on the brake pedal. I suspect we don't need the vac boost AT ALL. The problem is, we won't know until the car is pretty much completed.
So we are going to install it, but have a switch to turn it off or on. You may not need one at all. We'll see.
Jack Rickard
More Mini
Oh, the link to the videos for the Mini is http://evtv.me/mini.html.
We currently have an Intro video showing the features of the car and why we selected it for conversion. We also have our first conversion video which covers the wheels, brakes and suspension. This will give you a sample of the level of detail we intend, and just how boring these videos promise to be.
We installed the very best Brembo Gran Turisimo brakes on the front end, a 12.6 inch floating rotor with 4 piston fixed caliper. It should dramatically improve braking. To do this, we had to go to a larger 17 inch wheel. We used an ADR Venomous style wheels. This requires some conversion studs for the tuner lugs, and a 5 mm spacer to get the spokes to clear the calipers.
Jack Rickard
We currently have an Intro video showing the features of the car and why we selected it for conversion. We also have our first conversion video which covers the wheels, brakes and suspension. This will give you a sample of the level of detail we intend, and just how boring these videos promise to be.
We installed the very best Brembo Gran Turisimo brakes on the front end, a 12.6 inch floating rotor with 4 piston fixed caliper. It should dramatically improve braking. To do this, we had to go to a larger 17 inch wheel. We used an ADR Venomous style wheels. This requires some conversion studs for the tuner lugs, and a 5 mm spacer to get the spokes to clear the calipers.
Jack Rickard
2009 Mini Cooper Clubman
We have started our 2009 Mini Cooper Clubman conversion, actually some weeks back. I'm remiss in posting, and indeed the process will be MUCH slower than the Porsche Speedster.
We are trying to document each step of the conversion process. There are some 450 participants in the lease process from BMW for the Mini-E. At the end of a year, they are going to have to give them back. My intent is to do a BETTER conversion than BMW did, on a better car (The Clubman version instead of the S) and have it completed before the end of that period. But it moves very slow because of the overhead of documenting every bolt removal on video, and of course we are having to learn to shoot video and edit it, along the way.
The result is that this is going to be the longest EV conversion project in history. And the videos promise to be the longest, most boring videos in the world. I would love to compress it to 50 seconds and compete with "Charlie Bit My Finger" but the nature of the beast dictates probably 20 hours of video after editing.
This is gruesome. But potentially useful. If you want to do a Mini Cooper, it will pretty much show you all the necessaries. But be forewarned, I have expensive tastes, and like quality equipment. You'll have to make some changes to economize. We spent $32,000 on a brand new Clubman. And it's looking like about $35,000 just in parts for the conversion.
For a drivetrain, we have selected the MES-DEA 200-250 motor with a MES-DEA TIMS600 controller (http://www.metricmind.com) This is nominally a 30kW AC induction motor with a 400 amp 3-phase inverter/controller. We intend to operate with a 320v nominal 360 volt max battery pack made up of 100 Blue Sky 100 Ah cells.
This works out to about 128 kW of power. The motor actually delivers precisely 177 ft lbs of torque at 300 amps which is EXACTLY the torque delivered by the Peugot ICE engine that came in the car - at 1600 rpm. I think this is a SUPERB match to this vehicle, and gives us the ability to do regenerative braking.
This may seem an odd choice. BMW used the AC Propulsion 200kW drive train. We talked to them, extensively, and decided to pass. FIRST, their specs are just wishful thinking. They do 200kW about as well as I do with a AAA battery in my mouth. Second, their system is very much tied into their battery modules. The battery modules consist of 5088 individual cells assembled into modules. It is a design recipe for a fire. And the controller/charger doesn't deal with them particularly artfully when charging.
There wouldn't be much point in doing a video about converting a vehicle using components you can't buy yourself anyway. But after looking at the specs and talking with AC propulsion, we don't think its the best choice anyway. I DO like the idea of having a charger and inverter and DC/DC converter all in one box. But not this box.
The Blue Sky's are not quite as light and easily packaged, but we have a little more room in the car than the S model, and we think they'll be much more durable and less likely to cause problems.
We will again use the Brusa charger. To do higher voltages we'll use the NLG-513. Unfortunately, with a pack size of 36 kWh, this would take about 9.5 hours to fully charge and that's off of 240vac. The Mini-E lessees that were unable to get a 240 vac charge station approved have been seeing 120 vac charge times of TWO DAYs. Unfortunately, the laws of the universe prevail.
So we are going to be forced to install TWO of the Brusa chargers at about $3400 EACH. That's right - $6800 just for chargers for this vehicle. But it should bring us back down to a 5 hour charge process, quite programmable, and quite good for dealing with these LiFePo4 batteries.
We DO have an option. For $4400 you can get a Manzanita 75 amp charger. They have just released this new model, and if you can get your garage wired for a 75 amp 240 vac circuit (we can, we do our own wiring) which will probably be difficult to get a licensed electrician to do. But it has the potential to charge this car in less than 2 hours and for a third less cost than the Brusa.
It does NOT have the programmability of the Brusa. And it is far too large physically to have in the car unless you really want to give up your cargo space. But it would be less expensive. And it should be a monster. We've ordered one for the garage as a general purpose "quick" charger for all the vehicles. I would see hooking up the Manzanita for an hour, and then doing the finish charge on the Brusas during the day.
At night, I will simply use the Brusas. We'll use both for the bulk charge stage one and just one for the finish charge stages that require less current and more care.
We are trying to document each step of the conversion process. There are some 450 participants in the lease process from BMW for the Mini-E. At the end of a year, they are going to have to give them back. My intent is to do a BETTER conversion than BMW did, on a better car (The Clubman version instead of the S) and have it completed before the end of that period. But it moves very slow because of the overhead of documenting every bolt removal on video, and of course we are having to learn to shoot video and edit it, along the way.
The result is that this is going to be the longest EV conversion project in history. And the videos promise to be the longest, most boring videos in the world. I would love to compress it to 50 seconds and compete with "Charlie Bit My Finger" but the nature of the beast dictates probably 20 hours of video after editing.
This is gruesome. But potentially useful. If you want to do a Mini Cooper, it will pretty much show you all the necessaries. But be forewarned, I have expensive tastes, and like quality equipment. You'll have to make some changes to economize. We spent $32,000 on a brand new Clubman. And it's looking like about $35,000 just in parts for the conversion.
For a drivetrain, we have selected the MES-DEA 200-250 motor with a MES-DEA TIMS600 controller (http://www.metricmind.com) This is nominally a 30kW AC induction motor with a 400 amp 3-phase inverter/controller. We intend to operate with a 320v nominal 360 volt max battery pack made up of 100 Blue Sky 100 Ah cells.
This works out to about 128 kW of power. The motor actually delivers precisely 177 ft lbs of torque at 300 amps which is EXACTLY the torque delivered by the Peugot ICE engine that came in the car - at 1600 rpm. I think this is a SUPERB match to this vehicle, and gives us the ability to do regenerative braking.
This may seem an odd choice. BMW used the AC Propulsion 200kW drive train. We talked to them, extensively, and decided to pass. FIRST, their specs are just wishful thinking. They do 200kW about as well as I do with a AAA battery in my mouth. Second, their system is very much tied into their battery modules. The battery modules consist of 5088 individual cells assembled into modules. It is a design recipe for a fire. And the controller/charger doesn't deal with them particularly artfully when charging.
There wouldn't be much point in doing a video about converting a vehicle using components you can't buy yourself anyway. But after looking at the specs and talking with AC propulsion, we don't think its the best choice anyway. I DO like the idea of having a charger and inverter and DC/DC converter all in one box. But not this box.
The Blue Sky's are not quite as light and easily packaged, but we have a little more room in the car than the S model, and we think they'll be much more durable and less likely to cause problems.
We will again use the Brusa charger. To do higher voltages we'll use the NLG-513. Unfortunately, with a pack size of 36 kWh, this would take about 9.5 hours to fully charge and that's off of 240vac. The Mini-E lessees that were unable to get a 240 vac charge station approved have been seeing 120 vac charge times of TWO DAYs. Unfortunately, the laws of the universe prevail.
So we are going to be forced to install TWO of the Brusa chargers at about $3400 EACH. That's right - $6800 just for chargers for this vehicle. But it should bring us back down to a 5 hour charge process, quite programmable, and quite good for dealing with these LiFePo4 batteries.
We DO have an option. For $4400 you can get a Manzanita 75 amp charger. They have just released this new model, and if you can get your garage wired for a 75 amp 240 vac circuit (we can, we do our own wiring) which will probably be difficult to get a licensed electrician to do. But it has the potential to charge this car in less than 2 hours and for a third less cost than the Brusa.
It does NOT have the programmability of the Brusa. And it is far too large physically to have in the car unless you really want to give up your cargo space. But it would be less expensive. And it should be a monster. We've ordered one for the garage as a general purpose "quick" charger for all the vehicles. I would see hooking up the Manzanita for an hour, and then doing the finish charge on the Brusas during the day.
At night, I will simply use the Brusas. We'll use both for the bulk charge stage one and just one for the finish charge stages that require less current and more care.
Thundersky Batteries
We've received a lot of questions about the Thundersky LiFePo4 batteries we used in the 1957 Speedster conversion. I've done an hour and a half video on the topic of battery chemistry where I stumble through an attempted explanation of how they work. And we bandsaw a Thundersky battery into pieces and take it apart so you can see what's inside it. It's long. It's tedious. And I didn't spend a lot of time editing it. But here it is: http://evtv.me/movies/thunderskybat-desktop.m4v
There is a Yahoo discussion group specifically devoted to these batteries at http://tech.groups.yahoo.com/group/ThunderSky. I follow this discussion somewhat religiously. They basically compare notes on how to struggle through the battery management issues. I made the video in response to a discussion about what was inside the battery.
We're perhaps unique in that most people converting cars are trying desperately to do anything possible to protect the batteries - they are of course quite expensive. On the other hand, I am more or less in it for the knowledge and so we bring them to the point of failure, and often that means failure, more or less on purpose. At these prices, it still hurts when I blow one, but unlike most, I can be relatively casual about it and learn from the experience. So we sawed a blown cell up and disassembled it.
Enjoy
Jack Rickard
There is a Yahoo discussion group specifically devoted to these batteries at http://tech.groups.yahoo.com/group/ThunderSky. I follow this discussion somewhat religiously. They basically compare notes on how to struggle through the battery management issues. I made the video in response to a discussion about what was inside the battery.
We're perhaps unique in that most people converting cars are trying desperately to do anything possible to protect the batteries - they are of course quite expensive. On the other hand, I am more or less in it for the knowledge and so we bring them to the point of failure, and often that means failure, more or less on purpose. At these prices, it still hurts when I blow one, but unlike most, I can be relatively casual about it and learn from the experience. So we sawed a blown cell up and disassembled it.
Enjoy
Jack Rickard
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