LouMan's 94 Ford Aspire Electric Conversion

[vpoppv]

$30/piece for batteries is a really good price, but if you don't mind a little extra work, you can call all the places you have in the area that sell batteries and ask if they will sell you battery cores. Not very many places are willing to do it, so you have to make a lot of calls- or even better go in and talk to the manager and explain your project. Most of the batteries you get will be good and just need a charge. You can exchange bad cores for good ones elsewhere, and eventually you will end up with a good solid set to work with. I used to pay $7/each for battery cores, and now I found a place that sells them to me for $2. A word of advice though: don't leave your batteries outside. I got a whole bunch stolen that way.....

[Automcdonough]

ebay?? no kidding. Guess what other website I just opened...

[jackbauer]

drop me a pm with your address and i'll get the bits on the way.........

[Automcdonough]

lol ok well let me know which auction it is and I promise not to bid-war your friend.

[jackbauer]

Your biggest problem with used slightly old igbts is switching speed. That one in your spec is horrendously slow. I run a pair of fuji 1mbi800-u4l parts bought on ebay from a guy in germany. They are pritty slow and old 3rd gen parts but have yet to fail. I run 8khz switching frequency. I would look for a 5th gen part if you can get your hands on one. There is a guy in massachusetts on ebay selling some good parts. I'll try to dig out the details ......

[jackbauer]

Powerex IGBT, 400A, 600V, CM400DU-12F Mod 4 Piece Lot - eBay (item 190305777785 end time Oct-28-10 00:30:03 PDT)

these are the guys you need. I'm building a new controller with 4 off. Beauty is that you short the high side gate emitter and it becomes the freewheel diode. I'm using a 15v dc dc converter on the control board in place of the 12v for extra turn on power. Regards calculating the switching times yeh you can do the math but why bother. At the end of the day you need the lowest toff and ton that you can find and afford. Your 1200amp module probably has a very high gate charge hence the slow switching.

[jackbauer]

Those are both good modules for the vintage. That toshiba is widely used in forklift chargers being run at 20+ khz in a switching converter topology. I would still run at 8khz though as it makes life easier on the parts and reduces switching losses by 50% compared to 16khz.

[jackbauer]

Yeh i think the toshibas would work well. i'm too tired right now to go looking up switching times but i did drive them quite hard in a charger design quite recently and they worked well. 700v dc bus and 100amps DO put a good snubber between B- and M- and poly caps in parallel with the elecs. To my surprise my caps ( 4 big 400v comp grade elecs) are showing no sign of distress. Another ebay guy in new york sells caps at good prices.

[jackbauer]

no problem i'd had a few too many coffees! I'll send those bits asap.

[Automcdonough]

yes actually this is a precision area.. There's a few threads on here and over on diyelectric about how to set the motor brush timing.. this is one thing you don't want to blow off as a minor detail!