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Generator Voltage Regulator Adjustments and What the Coils Do

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  • Electrical: Generator Voltage Regulator Adjustments and What the Coils Do

    Here's a picture of the inside of the voltage regulator for my 1950 Champion. I have the screwdriver pointing to the spring tab that needs to be bent upward very slightly to lower the reading on the amp meter if the battery is fully charged but the ammeter still shows a high reading. Be sure to check the meter reading with the cover installed because the cover can sometimes affect the final reading. Some regulators have screws to adjust the spring tension, and this makes the adjustment much easier. The contacts for this voltage regulator should remain closed until the output from the generator exceeds about 7.3 volts. Then the contacts open and the output falls, so then they close again. This happens very rapidly and keeps the output at the correct level for maintaining a fully charged battery. You'll notice wire wound resistors on the bottom of the voltage regulator, and they shunt much of the contacts current, which helps to keep the contacts from arcing and burning up.

    The center coil is the current control coil and the contacts should remain closed until more than the generator's rated output is exceeded. If you had a short or a load of over 35 amps, then the contacts on the center coil should open if the generator's rated output is 35 amps, such as my 50 Champion is. This protects the generator from overload and burning up.

    The top coil in my picture is the cutout coil and stays open until the generator puts out more than about 6.5 volts. I adjust the open contacts gap to about .025" for the cutout. This cutout coil and contacts keeps battery voltage from feeding back into the generator and killing the battery and/or burning up the generator when the engine is turned off. Again, on this coil you can adjust the spring to make the contacts close at the correct voltage of 6.5 volts.

    Older Motor's Manuals are an excellent source for generator and voltage regulator information and adjustments.

    Click image for larger version

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    Last edited by TWChamp; 07-05-2015, 05:50 PM.