generator charging question

Ray · Feb 1, 2011

I have a 12 volt delco generator that i want to use on a tractor.The generator won't charge,but will motor if voltage is applied to the armature terminal.How can it motor but not charge?

Bob Bancroft · Feb 1, 2011

Some years ago I was changing an AC C over to 12 volts. It had worked well when I used a 12V gen. off a newer AC (D series) The guy I was dealing with had a gen. he wanted to get rid of. It wouldn't charge. Found out it was for an older JD. It didn't spin up fast enough on the AC. If yours has an original tag, and you can find someone with a chart, it will tell you all about it.

John T · Feb 1, 2011

Theres two parts to the Motor Test. First ground the FLD post to case/frame and apply voltage to the ARM post with case/frame grounded. If she spins good n smooth that says the Armature and Brushes and bearigns are in decent shape. Then unground the FLD and she should speed up a bit, if so the Fields are likely okay, if not they may be bad (shorted or open) in which case she wont charge correct. If it passes BOTH tests, it usually will charge okay.

John T

generator charging question

Ray

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Bob Bancroft

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John T

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