quick generator bench check

Sparky

Sparky

Well-known member
I have an old generator I'd like to refurbish. It needs a thorough cleaning and fresh paint, a new front bearing, one of the brush holder posts is loose, and the cloth wire insulation is flaking off, but it does spin freely. I didn't want to try testing it on my car because I was afraid it would self-destruct. So on my workbench, I connected a voltmeter to it and was able to spin it up with a drill as I held it with my hand. The voltage started climbing and when it reached 1-2 volts I could feel it trying to twist from the field starting to build up. Based on this, can I assume it is working OK?
 
A simple test is to hook 6 volts to it and see if it "motors" spins on its own. If it does then your fields and armature are sound, if it doesn't then you have a connection or electrical problem.
 
Your generator is probably good. They will start charging the battery when they spin about 750 generator RPM, which is 500 engine RPM.

When the field windings don't work the generator will only put out about 1/2 volt from the residual magnetism.

Liquid tape works great for small amounts of the cloth insulation flaking off.
 
Used liquid tape just this week to touch up insulation on a generator that was given to me. Great stuff for just this kind of fix.
 
I just used a compressor to blow off all the black dust from my generator's field coils, and noticed a flap of cloth that is loose. I don't want to "brush" the field coils, fearing I'll remove more cloth insulation. will "liquid tape" seal it up good without a super clean surface?
 
Henry's Lady's Man said:
I just used a compressor to blow off all the black dust from my generator's field coils, and noticed a flap of cloth that is loose. I don't want to "brush" the field coils, fearing I'll remove more cloth insulation. will "liquid tape" seal it up good without a super clean surface?
Click to expand...

Yes, brush on the liquid tape and the wrap should stay in place. I've done the same thing a few times.
 
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