Allis chalmers C generator wiring

Anonymous-0 · Jan 7, 2014

I have a C allis that the generator is not working. Someone removed the lights and light switch and hooked the field wire from the light switch to the negitive side of the amp meter. So there is no voltage control without the light switch. How can I fix the problem without insatlling a light switch? The amp meter is good but I do not know if the generator or cutout relay is good. I do know that when I hook up the battery ground wire that there is a current flow through the generator. If I disconnect the armature wire from the cutout relay the current flow stops. Is this telling me that the relay or generator is bad?

Thank you for your help

old · Jan 7, 2014

First thing I would do is check battery voltage with it not running then check it with it running. Not running you should have around 6.3 volts and with it running around 7 or so volts

Anonymous-0 · Jan 7, 2014

After I posted my questions,I removed and disasembled the generator. The generator is fried. I assume that when the lights and switch was removed that there wasn't any voltage control and that must have burnt up the generator.

steve(ill) · Jan 7, 2014

The light switch puts a resistor in series with the "F" wire to ground. When the lights are on, it bypasses the resistor and grounds the "F" directly. Grounding the "F" wire is a test to see if the generator is working. You dont need the higher charge all the time. IF you take the light switch out of service, you can add a big resistor on the "F" wire to ground so you get a constant 2-3 amp charge. I think its 3 OHMS, but no guarantee without looking it up.

steve(ill) · Jan 7, 2014

The cutout should be open when not in service. When the generator is running and putting out voltage above the battery, the cutout closes and current flows to the battery. If the battery flows backward when off, the cutout is bad.

Ted in NE-OH · Jan 7, 2014

It is fried because someone hooked the field terminal to the amp meter which is at battery voltage. The field only goes directly to GROUND (high charge) or to Ground thru a resistor for (low charge,)

chalmersbob(Pa) · Jan 7, 2014

You MUST remove the field wire from the amp meter.
The F wire goes to ground as was stated. If you connect the F wire directly to ground the genny will put out 10+ amps, but grounding through 3 ohm resistor it will charge 2-3 amps. You can do this though a toggle switch. hook the F wire and a 3 ohm resistor to 1 terminal of the switch and a wire from the other terminal and the loose end of the resister to ground. With the switch off the F wire grounds through the resistor. With the switch closed (on) the F terminal is connected directly to ground. Path of least resistance. Bob

Anonymous-0 · Jan 8, 2014

Thank You everyone for your help and knowledge. Now all I have to do is decide whether to install an alternator or find a 6v generator.
I think it will be cheaper to get an alternator but if I find a generator I will have your knowledge to do it correctly.
Thanks again

Bob Bancroft · Jan 8, 2014

Another possibility. I put a D series, 2 brush 12 V gen. and regulator on my C when I got it. Works great.

Allis chalmers C generator wiring

Anonymous-0

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old

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Anonymous-0

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steve(ill)

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steve(ill)

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Ted in NE-OH

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chalmersbob(Pa)

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Anonymous-0

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Bob Bancroft

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