jerry freedomev via EV wrote:
Hi Dan and All,
>
> Looked at EVDRive and interesting but I was trying to find a lower
> cost solution...

I think we can help you there. Controlling a Sepex motor is almost as easy as a series motor. :-)

As for 6.7" lasting I've been  abusing them for decades now and they
> take it well normally running at 2 x rated power even in Florida heat
> with a fan.

I agree. My ComutaVan, and my LeCar both had 6.7" motors. I never had a bit of trouble with them failing or overheating. Of course, I live in Minnesota. But you can easily add an external blower for cooling.

You might also try Bob Rice's solution. He used *two* golf cart motors, one per wheel. He switched them in series/parallel, to effectively have a 2-speed transmission. It also eliminated the differential.

I'm planning a very low drag  EV, 60-80wthr/mile so even at 50mph if
> the gearing lets it should be a problem.

You can also tweak the ratio with tire size, as you said.

First hitting the power  supply/field full on and then the start
> solenoid with resistor inline, then short out the resistor and then
> reduce the field to increase speed?

Yes, that's what I did for my very first EV. It was a 1974 Datsun pickup, with 72v of golf cart batteries in the bed, and a surplus 30v 500a aircraft generator for a motor. This is in effect a sepex motor.

My homemade controller used a big rheostat to control the field current. It was connected to the accelerator pedal. The armature was powered by a contactor controller, which could apply 36v or 72, with or without a series starting resistor.

It's important to wire it so you can't apply power to the armature unless there is field current. In my case, I had a relay coil in series with the field that had to be pulled in to enable power for the armature controller's contactors. If I dig around a bit, I can probably find my old controller schematic.

It was a very drive-able setup. Good speed control, smooth accelleration, and very strong regenerative braking. However, it was quite unlike any normal car's throttle response. The accellerator pedal behaved more like a cruise control; moving it caused the motor to try very hard to move to the new speed. In particular, removing your foot from the accellerator pedal commanded *full regen*, which would lock the tires on anything but dry pavement.

--
Whether we or our politicians know it or not, Nature is party to all
our deals and decisions, and she has more votes, a longer memory,
and a sterner sense of justice than we do. -- Wendell Berry
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com

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