case 1690

avant 1735 · Aug 22, 2019

I put an alternator on a 1690 tractor, 2 wires on the alternator, one to carry the current and one to excite the alternator. Everything was working fine for a few months. Now the voltage meter acts like a tach. when you rev the engine the voltage will max out at 16+ volts and when you let off to idle the voltage will drop to 8, no mater the rpm's. I checked the battery with a multimeter and it shows 12-12.5 volts. So any ideas why the volt meter is acting this way, when the alternator wont even charge above 13 volts. It did not do this when I first installed the alternator. Thanks

Janicholson · Aug 22, 2019

If the alternator is a Delco 10SI, or Hitachi 14231, it needs a sensor wire attached from #2 (or S) terminal to the output terminal. If it is a modified clone to be one wire, I would say it is failing. Alternator voltage less than the battery voltage could also mean that it is disconnected from the battery. Charged at rest battery voltage should be 12.6 volts. Charging (when fully charged) should be at 14.2 to 14.5 Volts. Jim

J.Wondergem · Aug 22, 2019

Sounds like the internal regulator went out.

Steve@Advance · Aug 22, 2019

If the battery voltage is that low, the charge is not getting to the battery.

Check the voltage at the battery stud on back of the alternator. It should be battery voltage.

If low or no voltage engine off, and high voltage running, there is a broken connection between the alt and the battery.

case 1690

avant 1735

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Janicholson

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J.Wondergem

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Steve@Advance

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