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I have a 69 BB that I have been chasing a charging issue for a while now. If running the car around town, no radio or acc the gauge read on the + side of 0. If I turn my running lights on, gauge drops to -20 and if I add the head lights, it maxes the gauge at -40. I have changed out the alternator and I have the same symptom, can this be a grounding issue, fusible link?
Rich
I would get that new alternator checked at the local parts store first -- my local parts store does it for free.....
If it indicates that it's ok, then perform the following checks:
Take the following voltage readings at the battery terminals:
Engine off
Engine running with no other electrical loads energized.
Engine off with loads added.
From what you are describing you have some compromised wiring and are applying 12 volts to ground with either of those systems energized. Pull the bulbs out of their sockets and with a VOM check to see that the sockets aren't totally grounded. Only the outside of the socket should be grounded.
I don't know if these carried through to '69, but I would change the voltage regulator if it is external. When you turn on your headlights, the sensor, or field, (I don't remember which of the two) wire is supposed to kick in another set of windings, or such, that increase the output. Sounds like this is not doing its job.
From what you are describing you have some compromised wiring and are applying 12 volts to ground with either of those systems energized. Pull the bulbs out of their sockets and with a VOM check to see that the sockets aren't totally grounded. Only the outside of the socket should be grounded.
Thanks, That's what I am starting to suspect. I drove the car yesterday and while driving I could watch the gauge and it would be charging for a good long time and then would suddenly drop to discharge. It did the a few times, so I have a shorted wire in the circuit somewhere.
Because the battery is so close attach an ammeter between the pos cable and battery (30a) scale if you have and after starting car or not turn your park and headlights on and see what kind of current you draw?
Another Alternator Thread
