Battery Charging Issues

Tim Workman · Aug 26, 2014

I noticed the other day on my Farmall C that my amp gauge was showing a discharge instead of a charge when selected on the light switch. It"s a 4 position. I replaced the brushes on the inside of the generator thinking that they might be bad considering they are the original parts. No joy when I got it put back together. Took the cover of the Cut-Out Relay off and noticed that one point would disengage and the other would not. All the wiring is correct and hasn"t been switched around.

Should I be in the market for a new Relay or should I be replacing the switch? Any troubleshooting ideas?

Russ from MN · Aug 26, 2014

I would take a volt meter and verify your suspicion before I would start buying parts. Ammeters are not necessarily that accurate.

El Toro · Aug 26, 2014

Measure your charging voltage across the battery terminals with the engine at 1/2 throttle or better. Should see about 7- 7.2 volts. Hal

Brian Jasper co. Ia · Aug 26, 2014

+1 more on check your voltage at 1/2 throttle or faster.
You can test the generator yourself. Disconnect both the A and F wires on the gen, then remove the belt. Run a hot wire from the battery (jumper cables work well for this) to the A terminal on the gen. It should spin fast like a motor with little or no arcing. While motoring, ground the F terminal to the case. The gen should slow down, but continue to motor. From there, load test all of your wires, a headlight bulb works well for this. Use each wire in a circuit with a headlight. Bright light = good wire. DO NOT use an ohmmeter for this. One slight strand of wire will show a good connection on the meter, but that strand will not be able to carry the current needed for the system to work.
Once you"ve passed all of the wires, and it still doesn"t work, make sure the regulator is grounded. Remove any rust or paint from the regulator mounting. Still not working, needs a regulator.

Owen Aaland · Aug 27, 2014

On a two contact voltage regulator the normal at rest position is to have the currant relay contacts open and the field control contacts closed.

As the generator starts to charge the currant relay should close and remain closed until the charging voltage gain drops to just a bit above battery voltage. The field relay should remain closed until the voltage from the generator reaches the upper limit of charging voltage. At that point it should start to rapidly vibrate between closed and open to maintain the proper charging voltage.

Battery Charging Issues

Tim Workman

New User

Russ from MN

Well-known Member

El Toro

Well-known Member

Brian Jasper co. Ia

Well-known Member

Owen Aaland

Well-known Member

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