# Planning 1997 BMW Z3 conversion



## dimitri (May 16, 2008)

Z3 is a great donor, several been done, look at EVAlbum. 97 would not have sophisticated ECU to worry about, plus you can just ignore most of it if you have manual transmission.

Lots of battery room under the hood. I don't get your commend about FWD or RWD? How is that even a choice in a RWD car? Warp9 would be perfect choice for such car.

I used to own a Z3 and loved it, but had to sell it to fund my first Miata conversion. I couldn't afford to gut Z3, but your 97 seems like a great project. 

Please, don't kill such great potential conversion by going after Lead Acid batteries, try to stretch your budget and go with LiFePO4.

Soliton Junior would make a great controller for this car along with Warp9 motor. I would use 100AH cells and try to pack as many as possible for high voltage, which will get you good performance.

Post pics, we all love pics! Good luck with your project!


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## dtbaker (Jan 5, 2008)

yeah, yeah, go for it if you can get a good price on donor!

8" motor will be marginal as you probably don't want to push past 120v. better with 9"dc and a controller capable of some amps off the line as the Z3s are kinda heavy. for 40-50 mile range, you'd be ok with 100ah Li at 120v-144v.

count on a little more $$ though.... allow $6-ish for electrics, and another $5k-$6k for batteries.


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## Yabert (Feb 7, 2010)

Like dtbaker said, 5-6k$ for battery is accurate, but you can probably pay less than 2000$ for all electrical if you can build your controller and if you can find and rebuild an old forklift motor. But it's a lot of work.

The easiest way is to buy the Soliton Jr to control a Kostov 10" motor at 144 to 192v.

What kind of performance do you need? (acceleration and top speed)


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## jiggapoo (Apr 6, 2011)

dimitri said:


> Lots of battery room under the hood. I don't get your commend about FWD or RWD? How is that even a choice in a RWD car?


I was wondering the same thing! I assume people do not not retrofit other, lighter, drivetrains for the purpose of efficiency or weight. But I guess that would make it no longer a Z3 if it drove like a Subaru (or Metro).


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## jiggapoo (Apr 6, 2011)

Yabert said:


> What kind of performance do you need? (acceleration and top speed)


Well... a 4 cyl Z3 is mostly a dog to begin with (compared to most sporty roasters) with 0-60 in the 9-10 sec range. And I'm not concerned with top speed or acceleration as most of my driving is stop-and-go with speed limits around 45. In the '97 1.9L, at least, the 'fun magic' of the car is all in the diff, which is geared to really suck your gas mileage in the hopes that you won't notice your crummy performance. Now you know why they only put the 4cyl in that car for two years.


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## jiggapoo (Apr 6, 2011)

dtbaker said:


> count on a little more $$ though.... allow $6-ish for electrics, and another $5k-$6k for batteries.


So we're looking at a marginal cost of $125 / battery? I assume there are good links to 'where to buy' elsewhere on this site...


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## dtbaker (Jan 5, 2008)

jiggapoo said:


> So we're looking at a marginal cost of $125 / battery? I assume there are good links to 'where to buy' elsewhere on this site...


for a 40 mile useful range (no more than 70%-80% DOD) you'll need at least 38 x 100ah cells giving a nominal voltage of 120v. Using 100ah cells you should be moderate with the accellerator, and try not to go over 3C (3 x 100ah=300amps) very often for very long. So, a 'wimpy' but relatively inexpensive controller like the Curtis 1221c which can only put out a max of 400amps would keep you out of trouble. Or, since you have such a cool car, you might consider a more expensive, but more flexible controller like the Soliton Jr where you could program it to allow 500 or 600 motor amps, but no more than 400 battery amps.... etc.

If you go with a Netgain Warp9, you can bump the voltage up to 144v with a couple more cells, which would give a lot more zip, and a little more range... you'd need to move up to a Curtis 1231c on the lower end, or strongly consider the soliton jr., raptor, or some other 'performance' controller.

with 144v, Warp9, and a controller able to dump in 500-600 motor amps off the line, I'd guess the z3 would perform WAY better than stock.

battery suppliers have been somewhat problematic. There have been a few dis-honest ones (the infamous EVComponents debacle with James Morrison) that have us all a little skittish a this point, especially with the Thundersky supply lines involving pre-pay FOB from China. You should check out the 'Vendors' category and do a little homework to make your own decisions. The supply of CALB batteries seems much more responsive right now with prices ranging from $1.25-$1.45/ah. Vendors I have had good luck with include kta-ev.com (no batteries), EvolveElectrics.com (stuff including batteries), currentevtech.com(stuff including batteries).... you should contact them and order from stock as waiting for shipping FOB china is questionable.


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## Dodje (Apr 8, 2011)

http://yushenke.net/energy/radiantnaya/tesla_switch.html


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