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Bench testing an old 6-volt generator...how to?

15K views 6 replies 5 participants last post by  highlandlake 
#1 ·
Hi everyone reading this,

I'm working on a '51 Flathead 6-cylinder engine. The generator is a 6-volt type and has not been run for many years. In it's original condition, I bench tested it as-is. My method was to hook up a voltmeter to the output and ground terminals. Then I took a 20-foot long piece of twine and wrapped it around the belt pulley. I pulled it as hard and fast as I could. The meter read 0.5 volts.
So spent a couple of hours disasembling the unit and gave a very thorough cleaning. I replaced the armature bushings with new ones. Used 0000 steel wool on all the inner contact surfaces and gave them a shine like new. Vacuumed and blew out all the dust and wool debris. Cleaned and polished all the terminals.
It looked great, shined like new inside.
After putting it back together I did the twine trick again and got the same result....0.5 volts at the highest speed I could spin it. Turning it slowly by hand will get about 0.15 volts.
So, what am I doing wrong? Should the generator be spinning at 1000 rpm or more to get a 6-7 volt output?
Any advice or suggestions to test the output when it is on a bench?
Thanks,
Tom

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#2 ·
How I use to do it is , Hook up two 6 Vt. leads to the gen. If it is working it will run BACKWARDS like a 6 Vt. D.C. motor. My Dad showed me this in 1956.
Bob
 
#3 ·
Still wondering how to check the output voltage when the unit isn't on a running vehicle.

(Bob, thanks for the reply about how to check if it will turn, not quite ready to do something like that, but haven't ruled it out if I have nothing else to try :))
 
#4 · (Edited)
The output voltage for something made in 1951 would be controlled by the voltage regulator. I cannot remember if you need to ground the F(ield) terminal or hook it to the A(armature) terminal for doing you test. Either way , you cannot hurt anything. If you can, find an old old Motors Auto Repair manual that would have info on these generators.

edit: you could PM a TCer named Stellar, as he works in the automotive generator, starter and alternator biz and I think he is a pretty helpful guy.
 
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