I recently replaced my generator with an alternator in my ’53 half ton pickup (converted to 12V negative ground) and botched the job. I created a short that was draining my battery. I think I’ve found and fixed the problem, but before I mark this case closed, I want to find out if a couple of unusual readings I’m getting indicate another problem.
I’ve disconnected the battery cables and turned everything off. The truck has no clock so there should be no continuity through the electrical system. But, when I put an ohmmeter between the battery cables I get a 1.75 ohm reading. When I move the ohmmeter to the new alternator and take a reading directly across the alternator I see the same 1.75 ohms. So, I have continuity through the electrical system even when everything is turned off and the current is going through the alternator.
Next I reconnected the + battery cable and inserted an ammeter in series between the battery’s minus terminal and the ground strap. The ammeter showed 2mA. Everything was still switched off so the current must have been going through the alternator.
Is this normal or is there something wrong with the alternator? Are these readings acceptable or should it be showing no continuity through the circuit?
I don’t drive the truck every day and the whole reason for switching to an alternator was because I was tired of charging the battery every couple of weeks. How long will a 2mA draw take to kill my battery?
And another thing . . . not that it really matters . . . just out of curiosity . . . but, why is the current so low? If I take 12 volts divided by 1.75 ohms I get 6.86 amps.
