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Hi all, my project is not a ev conversion persay, but this forum seems to be the place where I might find some answers.I have a 48 volt sepex golf cart I have converted to lithium ion using leaf cells. I have not beeen able to locate any information concerning the stock motor other than it is a GE 3.2 hp at 3060rpm. I have also installed a alltrax xct72500 controller good for up to 80 volts which i plan on getting to eventually. Can anybody tell me what the insulation is good for in this motor or a general guideline for brushed dc motors I know the lowest rating for a nema motor is 105c I would think it would be good for at least that but I dont know. The mechanical rpm limit i am told is 6000 rpm, does that sound about right and is their any way to increase that? Is the most heat produced in the commutator and the heat path mainly out through shaft and bearing? Or is the whole armeture approximately the same temperature?
 

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I can help with some of this.

Can anybody tell me what the insulation is good for in this motor
Temp-wise, typically Class H.

Class A = 105'c
Class B = 130'c
Class F = 155'c
Class H = 180'c

But see if you can dig up a datasheet or, if it says on the label.

This is for 20,000H of runtime before insulation failure.

Voltage-wise, typically any insulation will hold up north of 150v.

The mechanical rpm limit i am told is 6000 rpm, does that sound about right
DC motors are generally not speed limited by their bearings, but by the edge forces on the exterior of the comutator, which is spinning. Bigger motor, bigger commutator, edge speed is faster. It will rip itself apart from being spun.

6000 RPM for a golf-kart sized motor sounds about right. Other ratings you can bend, but this one I would adhere to as a genuine do not cross line.
 

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Hey thanks for the info, It is hard to come by on anything golf cart related. Is there any other thermal limits in a brushed dc motor other than insulation value? I have tried to dig up a data sheet and no go. The motor tag or lack thereof only lists hp, the rpm I had to find on the web. And that is pretty much all the information that you can find on a motor of this type. My research indicates that sepex and shunt mean the same thing is this true?
Thanks again
Russ
 

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My research indicates that sepex and shunt mean the same thing is this true?
No, not the same thing.
In a shunt-wound brushed DC motor, the field windings are connected in parallel across the armature winding, via the brushes and the commutator. The field is "shunted" across the armature.
In a separately-excited ( sepex ) motor these two parts are completely separate electrically. Power for the field windings is connected and controlled independently from the armature.
 
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