How to test discharging generator

[Larry B.]

Went for a cruise in the '61 and the ammeter gauge suddenly showed a discharge. I put a voltmeter on the few month old battery and the car was running off the battery at a little over 12 volts. No voltage change or charge when raising the RPM'S.

Grounded the regulator field wire to the regulator case and no change in voltage. Jumped the generator regulator terminal to the regulator batt terminal and just a very very slight drop page in voltage.


How do I isolate the generator from voltage regulator as the culprit? Battery is good and holds a load test. Thanks

[Larry B.]

Re: How to test discharging generator

Anyone have an answer?

[Jim D.]

Re: How to test discharging generator

The easiest and best way to check output AND rule out the volt. reg. is to disconnect all the wires from the generator, hook a volt meter to the arm. terminal and start the car. You should have between 2-6 volts. Now ground the field terminal and you should get over 15 volts when you rev. the engine. If you do, you have a bad regulator (assuming your wiring is okay). If you don't, you have a bad generator. Simple as that.

[Robert S.]

Re: How to test discharging generator

Sounds like you may have run out of brush material. It is easy to change the brushes on a generator. Try this and see what happens. May cure the problem and it can't hurt.

[Terry B.]

Re: How to test discharging generator

Last year my generator stopped charging and I determined that there was no output from it. As I was removing it to rebuild it the blue wire fell off. Moral of the story, check those wire carefully before tearing apart the generator.