On Mon, Jan 1, 2018 at 2:34 PM, Lee Hart via EV <ev@lists.evdl.org> wrote:

> 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.

I have ad heat issues with my motors, likely from the continuous loads from
pushing the blower through deep snow.   An ammeter and digital thermostat
proved it- I would pull 100 amps continuous with peaks to 300 amps going up
our big hill.  You would think the motor would stay cool in -10 and the
occasional snow pile hitting it when backing up but the temps would hit
over 120c on the case  before I started actively cooling it.  As well,
without active cooling those temps would remain high for 2+ hours with the
cart shut down.   Smooth, sealed iron bodied motors that are tucked up
under the seat don't get much cooling.   If you are rolling down streets
without big hills there should be enough time between loading to dissipate
some heat but understand the heat takes a long to time to fade.  High
gearing and extra passengers will increase those temps.

> 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.

Would love to see that setup!  I have two diffs and more than two motors in
parts..  I also have another MARS ME1003 I have been gearing up, have the
coupler made just need to finish the adapter mount.  It's an aluminum
bodied, open with an internal fan motor, much better cooling ability and
power output.
Does anyone know how much the dana/ spicer diffs can handle?  I can limit
the current at the controller so it doesn't grenade immediately.

> 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.

I picked another golf cart this summer (defunct EGT electric) that has a
Curtis controller and a Hall pickup on the Sepex motor.  The controller
limits the current based on the hall pickup speed.

> 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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