Topic: Erratic charging/ overcharging


old 40 guy    -- 05-06-2016 @ 6:02 AM
  Problem: Car (1940, 85 hp with rebuilt 2 pole generator and new wiring and regulator) shows overcharging (in the red to right of green on battery gauge)and wild readings on voltmeter (readings change constantly 3-4 times per second, and fluctuate from 2 to 24 volts and everything in between when car is running.
Battery reads 6.3 volts before starting. Volt reg is polarized and well grounded with separate ground wire; generator is grounded; wiring appears to be correct; swapped out regulator for new and got same result; swapped our generator with same result. Removed ground from battery with engine running and engine continued to run which would indicate it is the regulator ?? Need help - what additional tests can I do. Could problem be shorted battery or a problem with the headlight resistor unit under the dash ??


old 40 guy    -- 05-06-2016 @ 7:05 AM
  Additional info - this is standard/ unaltered 6 volt system; distributor and coil rebuilt by Skip Haney; taking volt readings across the battery and at regulator "bat" terminal and ground; turning on headlights moves battery gauge slightly to the left but still remains in the red zone. Engine starts and runs fine.


TomO    -- 05-06-2016 @ 7:27 AM
  It sounds like a grounding problem to me. Connect a jumper wire between the voltage regulator ground and the generator case. If the voltage meter settles down, clean the generator mount and the area under the regulator mounting screw that is grounded.

Also make sure that the ground strap from the firewall to the battery and from the fire wall to the engine are in good shape and are mounted to clean surfaces.

Tom


pauls39coupe    -- 05-06-2016 @ 7:25 PM
  I agree with Tom O that you likely have a ground problem.
If you are using a digital volt meter, it will fluctuate all over the place from the magnetic field produced by the generator, and radiation from the steel plug wires. Find an old style analog meter (one with a scale and pointer) they are more stable when working on these old Fords.


old 40 guy    -- 05-09-2016 @ 4:12 PM
  Just want to say thanks to Tom O - you were correct - bad ground. Cleaned every connection - working perfectly. Very greatful.

Also thanks to Paul - the old school analog meter did the trick - no erratic readings. Thanks.


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