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Re: (ET) Motor overvoltage



Being an electrical dolt I tend to understand this stuff on the most basic level.  Maybe I can add some value here, even if only in a simplistic sense.
 
In ICE design you juggle a huge variety of parameters and strike many compromises to get as much of the energy in your fuel as possible to the ground.  An electric motor, however, will do a very good job of delivering whatever you feed it.  The object of electric motor design then is to withstand the power it's managing.
 
So yes, your 36V motor will certainly handle 48V.  The question is how long.  Will it overheat?  Will the brushes and their pigtails handle the increased amps?  Are the shaft, bearings, etc. up to the increased torque?
 
You may be only looking at a shortening of its life, and probably not by much.  If it will be used lightly, maybe that doesn't matter.  Also keep in mind the original 36V rating is probably continuous.  How frequently will you be giving it the full 48V?
 
If it was me I'd try it and tread lightly at first.  I think there's a good chance it will take 48V just fine.  If it starts showing signs of stress, a supplementary fan might be all you need.
 
This link to Neon-John's upgrade of a GE Citicar motor might be useful:
 
http://www.neon-john.com/EV/motor_repair/motor_repair.htm
 
Chris

On Sun, Aug 3, 2008 at 10:23 PM, Max Hall <maxo iname com> wrote:
For whatever it's worth, Bill, I drove a 36v golf cart drive assembly (motor, diff, axle, oversized wheels, even) at 72v for tens of miles (maybe more than 100) in one phase of an EV project. I later used the motor for something else... it's still in "circulation' in my projects... and it never seemed any the worse for wear. (I think I had a 275A max current at 72v, or about 20kW, and I wasn't shy about using it, either.)

If that GE motor is really precious to you, a family heirloom motor, for instance, don't do it. If you can stand the *possibility* of it failing, then I think you should wire it up with confidence; my bet is you'll be fine.

 
Confessions of an overdriver,
-Max

On 8/3/08, Bill Alburty <willaim kc rr com> wrote:
I have a 36V Cushman golf car with a GE motor. Does anyone know if I can
increase its speed by increasing the voltage to 42 or 48 volts without
damage to the motor?

Thanks,
Bill  Alburty


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