Is My Motor Too Small For My EV Conversion?

by Bill
(Warner Robins, GA, USA)

I want to use a 10 hp motor (approx 7500 watts and 3500 rpm with a 1:2 gearbox) with an Allen-Bradley power flex 40 drive, and a good potentiometer for the accelerator. The AC power however would come from a 3 phase gas generator. Is the motor too small?

I saw where you suggested a higher wattage motor in a previous question. Doesn't the transmission and rear end do the work if geared right? The vehicle I believe has a curb weight of 3300lbs (80's Firebird). I don't expect the car has to go over 80mph.

Hi, Bill -

I think you left a lot of stuff unsaid, here, and now I'm dying of curiosity.

Like, how big is your generator?

If you enjoy driving your electric car on the freeway, it will take at least 30hp to get there without batteries, according to my new friend, Alain St. Yves.
You don't mention a thing about batteries, so I don't know if you're planning to ditch them and power your motor only with the generator or not.

About the size of your motor...yeah, I think it's too small. Especially with a curb weight of 3300 lbs, that's pretty heavy.

When you're going transmission-less, you want a bigger one, not a smaller one. I'm not going to tell you that size doesn't matter. (Sigh.)

Maybe you should ask the guys at the EV Discussion List? They might have more to say about just how much you can get away with in the gearing department.


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