Quote Originally Posted by bmorgil View Post
We need LarrBeard to pipe in here but, I would be looking at the regulator. It might need adjustment.
Herr von Klepper:

We “Old Guys” don’t mind answering the “Why isn’t my battery charging; what’s wrong with my generator?” questions. It makes us feel like we’re still important! Here is more than you probably want to know....

Disconnect the Field lead from the generator (at the generator case), that would generally be the smaller of the two terminals. Since you have a rebuilt – donated – generator, make sure you have Field and Armature figured out correctly.

You are going to ground the field terminal; by doing this you are going to bypass all of the relays and resistors in the voltage regulator and put the generator at close to full output. The most conservative way is to make up a test lamp (12-volt tail light bulb), hook one lead to a good frame ground and with the motor running, connect the other to the Field terminal. This allows a bunch of current to flow through the Field windings. The bulb should light up (it should be pretty bright) and you should get a + reading on the ammeter. This connects the light back to the battery through the Field windings and brushes, but limits the current through the Field coils to what the lamp would normally draw. (An 1141 bulb will draw about an amp or a little more – it might not bring the generator to full output, but it will give you an idea if things are alive).

The other less conservative way is to just take a clip lead and ground the Field terminal directly. This will put a LOT of current through the Field windings, so do not hold it too long or magic smoke will come out of somewhere, usually the insulation of the clip lead. This should put you at a hearty + reading on the ammeter – full output of the generator. Really old timers called this “full fielding” a generator.

This should give you an idea of your generator’s ability to turn RPM’s into amps. If you don’t get amps with these tests, I suspect an issue with the generator. If these checks give you amps, I’d replace the regulator. Defective (but new) voltage regulators are rare but not unheard of. Adjusting one is almost never necessary and it takes a lot more “stuff” that most of us want to fool with these days.

Good luck, let us know what you find – and we’ve not seen any pictures of the project lately.