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How to test generator output

John Hood I have a 1947 John Deere A with a Delco Remey generator. I bought a new regulator and after installation I turned on the lights and noticed they got bright and then it blew a 25amp fuse I had installed in the power curcuit. Any ideas on how to check the generator. I think it is putting out to much voltage. Thanks.
Dale G. Basgall John : The generator is a permanent magnet motor, the faster you spin the generator the more voltage is present and inversley the more voltage applied to the generator the faster it will spin as a motor. So a permanent magnet generator can be used also as an electric motor. Like the Wisconsin engines in the old days using the generator as a starter motor for the engine.

Remove the wiring from the generator and start up the tractor, use your digital volt ohm meter to check the output voltage. One lead goes to ground and the other to the big terminal on the generator case. You will find that as you increase the engine rpm, if the generator is working well the voltage will go up as the rpm is increased.

The important part is the regulator, it regulates the voltage to the battery and system, these can be wired independent to the tractor ignition wiring. As long as the generator rotates you should be getting voltage.

Dale G. Basgall

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