The Ford Barn - View Single Post - Generator not charging-where to start?

nkaminar · 07-03-2023, 03:50 PM

Use a voltmeter. Set your multimeter to the DC volt scale. The 20 volt scale should be fine. Run the engine at a fast idle, about 1,000 rpm. Measure the voltage at the generator stud, opposite side of the cutout from where the wires hook up. You should see either about 7 volts or 14 volts depending on whether you have a 6 volt or 12 volt system. If that is OK then measure again at the wire side of the cutout. If this is at the battery voltage then the cutout is bad. The generator can be putting out much more that the 7 or 14 volts if it is not connected to the battery. If this is the case, do not run the engine very long, just half a minute or so, or you stand the chance of burning out the generator. If the generator is less than 7 or 14 volts, then it is bad or the third brush is not adjusted correctly.

Also check all the wiring to make sure that there are no open circuits or short circuits. You can use the ohm scale on your multimeter.

A good site for all things electrical on a Model A is https://www.mafca.com/downloads/Semi...ex%20Janke.pdf

07-03-2023, 03:50 PM	#10
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 3,950	Re: Generator not charging-where to start? Use a voltmeter. Set your multimeter to the DC volt scale. The 20 volt scale should be fine. Run the engine at a fast idle, about 1,000 rpm. Measure the voltage at the generator stud, opposite side of the cutout from where the wires hook up. You should see either about 7 volts or 14 volts depending on whether you have a 6 volt or 12 volt system. If that is OK then measure again at the wire side of the cutout. If this is at the battery voltage then the cutout is bad. The generator can be putting out much more that the 7 or 14 volts if it is not connected to the battery. If this is the case, do not run the engine very long, just half a minute or so, or you stand the chance of burning out the generator. If the generator is less than 7 or 14 volts, then it is bad or the third brush is not adjusted correctly. Also check all the wiring to make sure that there are no open circuits or short circuits. You can use the ohm scale on your multimeter. A good site for all things electrical on a Model A is https://www.mafca.com/downloads/Semi...ex%20Janke.pdf __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.