Ford Jubilee Electrical Problem

Larry Kastens · May 4, 2022

On our Ford Jubilee (NAA), what would cause the generator to overcharge? The voltage regulator and the ammeter are new. When the engine is running, the ammeter needle jumps around and when the needle is still, it shows a 30 amp charge.

Thanks to anyone who responds
Larry Kastens
Hereford, Arizona

Sean in PA · May 4, 2022

Sounds like the meter itself may be problematic. Get an accurate multi-meter and set it to amps and put it in series with the one in the dash and make sure that the tractor is really pulling that many amps. If it really is pulling 30 amps, measure the voltage across the battery. If it is much above 14.6 volts with the engine running then the generator and/or VR are not working properly. Also, if it really is pumping 30 amps into the battery constantly, don't expect the battery to last long, as it will boil away the water in the electrolyte in short order. If the voltage is good (between 13.5 and 14.6) when running, then another possibility is some other load in the circuit that is drawing a lot of amps through itself to ground.

Larry Kastens · May 4, 2022

(quoted from post at 18:09:28 05/04/22) Sounds like the meter itself may be problematic. Get an accurate multi-meter and set it to amps and put it in series with the one in the dash and make sure that the tractor is really pulling that many amps. If it really is pulling 30 amps, measure the voltage across the battery. If it is much above 14.6 volts with the engine running then the generator and/or VR are not working properly. Also, if it really is pumping 30 amps into the battery constantly, don't expect the battery to last long, as it will boil away the water in the electrolyte in short order. If the voltage is good (between 13.5 and 14.6) when running, then another possibility is some other load in the circuit that is drawing a lot of amps through itself to ground.

Thank you. It is a six volt system with positive ground. We also changed the ammeter the second time, and it did the same thing, so likely it may be the generator. Do you know of a way one can check the generator to show how many amps it is putting out?

Sean in PA · May 4, 2022

Sorry, I should have realized it might still be 6 volts. You should be measuring voltage, not amperage, when testing the generator and VR. How many volts does it measure across the battery when the engine is running and the ammeter is showing 30 amps? If it is between 6.7 and 7.3 volts then the charging circuit is working correctly.

Larry Kastens · May 5, 2022

(quoted from post at 19:51:49 05/04/22) Sorry, I should have realized it might still be 6 volts. You should be measuring voltage, not amperage, when testing the generator and VR. How many volts does it measure across the battery when the engine is running and the ammeter is showing 30 amps? If it is between 6.7 and 7.3 volts then the charging circuit is working correctly.

Thank you, Sean. We will check that out next week. Thanks.
Larry

Larry Kastens · May 7, 2022

Thanks to those who responded. It turned out to be a defective voltage regulator.
Larry

Ford Jubilee Electrical Problem

Larry Kastens

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Sean in PA

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Sean in PA

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