1961 generator output testing

[The Okay Boomer]

Hello classic T-Bird community. My 1961 (390 cu in, convertible) has a charging issue. My battery slowly drains as I drive the car. I need to charge the battery every few weeks to maintain 12.7 volts (engine off). I've installed a new battery, and a new voltage regulator, but the voltage still decreases as I drive. My battery is at 12.7 volts with the engine off. After starting the engine, it increases to 13.2 volts initially. Then it decreases to 12.5 volts after idling a few minutes. If I turn on the heater fan, it drops to 12.2 volts. I suspect the generator is bad. Can you please tell me how to test the generator output? Can it be tested with a multi-meter? Appreciate your advise. Thanks.

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[Frankie the Fink]

A generator should put out between 13.8V to 14.2V at a fast idle as measured across the battery terminals...pretty steadily.

If not there is a problem That is your test. The measurements you cite will not keep your battery charged nor your accessories properly powered (e.g. dim lights, etc)..

UNLESS you can find somebody with an "old school" growler (not many around now).

You will have to find a specialty shop to get it properly checked out.

The generator could be weak, need brushes or a fan belt could be too loose.
Did you polarize the system when you replaced the voltage regulator ? And is it a repro ?
Some of the repros are just terrible.

 

[Mrjagrock]

Some of the Parts stores (Auto Zone, Oreillys) can check your Generator output for free!