# 2nd and hopefully last new question for tonight. (homemade controller)



## Mr. Sharkey (Jul 26, 2007)

Don't do it. You'll spend more money replacing dead and dying batteries in the first year than a full-featured controller would cost. EV batteries need to experience identical discharge/charge profiles to be kept healthy. Switching them in and out of the circuit, besides being an electrical engineering nightmare, would cause the batteries in the lowest end of the pack to be discharged more than the ones in the higher end. Result = unhappy batteries that will bite you in the wallet to get even. Stick with modern, soild-state controller technology, it's worth it. If you're very clever, you could design and build your own to save $$$.


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## houseoffubar (Nov 18, 2007)

Mr. Sharkey said:


> Don't do it. You'll spend more money replacing dead and dying batteries in the first year than a full-featured controller would cost. EV batteries need to experience identical discharge/charge profiles to be kept healthy. Switching them in and out of the circuit, besides being an electrical engineering nightmare, would cause the batteries in the lowest end of the pack to be discharged more than the ones in the higher end. Result = unhappy batteries that will bite you in the wallet to get even. Stick with modern, soild-state controller technology, it's worth it. If you're very clever, you could design and build your own to save $$$.


 Not to mention the switches to turn on, and off the batteries would take a beating, trying to switch on and off the full fury of each battery (lots of amps)


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## Devon Hynes (Dec 7, 2007)

I was thinking starter relays, but anyways thank for your help.


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## houseoffubar (Nov 18, 2007)

Devon Hynes said:


> I was thinking starter relays, but anyways thank for your help.


 They make big contacters, that people have used like this in the past. I read about an EV built in the 70"s that did this, but had problems with sticking contacters, etc. This is why the motor controller was developed. They work so seamlessly, that there really is no other practical option.
You can find controllers used for quite cheap. old forklifts, power pallet jacks, ETC. Check out Ebay, type in Curtis, or DC motor controller and see what you find. Also check out project forkenswift, He built his car for a few hundred $http://www.forkenswift.com/


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## david85 (Nov 12, 2007)

Forkenswift, I highly recomend you check that conversion out. They made a few Utube episodes that were quite clever (used sound bites from GM's promo for the EV1).


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## Devon Hynes (Dec 7, 2007)

The Forkenswift is exactly what I needed to see, thanks allot to everyone who replied to both my questions. I have a preatty good idea of what I want to do, my eyes are on a shell and hopefully if I can convince someone that it would make a good Christmas present I should have the ball rolling soon.

p.s. I was starting to think ummm maybe not for me, but when the gas light in my car came on today that was the deciding factor. Thanks agian everyone.


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