The Stovebolt Site Forums The Shop Area The Electrical Bay 6 or 12 volt generator?

Hi,
I am working on a 1946 Chevrolet Utility, 12 volt system. Upon teardown of the front clip to replace the harmonic balancer and water pump, I noticed the generator end frame is cracked and the flange is damaged. I have a few generators sitting on the shelf, but do not know if they are 6 or 12 volts.

Is there a visual way of determining a 6 volt or 12 volt generator? If not visual, can I use a volt meter to test for 6 or 12 volt?

Thanks,

Dale

Check the ID tag riveted to the generator.

Black tag = 6v
Red tag = 12v

Thanks OlBlue,
The generator on the truck is missing the ID tag, and has 12V stamped on it. On the other ones, I am not sure if the tags are still there. What I am interested in is a bench test?
Or can I install one off the shelf, mount it on the engine with no wires attached and get a voltage reading?

I ran mine on the bench with an electric motor and belt. With the field grounded and no load it produced 20 volts. That was a six volt.

Great, do you know what the RPM of the motor was? If I use the engine as a test stand, will the voltage output increase/decrease with the engine running at various RPM?

Try measuring the field coil resistance with an ohmmeter, from the "F" terminal to the insulated brush holder. Use your known 12V field coils as a reference. If there's a noticeably lower resistance, you've got a 6 volt field coil set. I don't know of a quick way to identify a 6 volt armature.
Jerry

Edit: With no wires connected and the armature turning, a polarized generator will produce about 2 volts at the armature terminal, but there's no way to predict where the voltage will go with the field grounded and the armature terminal open-circuited. It would have to be connected to a battery so it can generate some current. Open-circuit voltage can go above 50 volts, and it just keeps increasing as speed goes up.