Alternator Low Volt Observation and quick fix..

I thought I'd post up an observation of how my alternator was (or was not) pushing current through the system and a small 'fix' I made today.

I was noticing through my Scangauge that I only had around 12.5 V on my battery just after start when it should read between 13.7 and 14.2 V. Not only that it would bump down to 12.4 then 12.2, etc. Obviously I'm not getting juice from the alternator just after start. When I took it out for a spin it suddenly spiked back up to 14.1 V then settled around 13.8 after about a 1/4 mile.

I tested at alternator by putting a multimeter positive to the A+ contact and the negative to the chassis and it mirrored the battery voltage of 12.4 just after start. (note: if you put the multimeter to the pos and neg posts you'll get some kind of reading from the voltage regulator, not the output of the A+ stud)

I took a wire brush and cleaned the base areas around + and - posts AT THE ALTERNATOR and what do you know, 14.1 V to the battery right after start.

I easily could have written this off as a bad alternator and there would have gone another few hundred dollars and a few hours of my time.

I guess I got lucky there was a connection at some point after I got moving prior to cleaning the contacts.....

Thanks! Filing away.

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Yeah I had really similar symptoms going on with my van that finally resulted in a no-start condition. I wasn't quite as patient as you with my diagnosis so a new alternator and new starter ordered and it was a loose grounding strap attachment bolt that took about 6 seconds to fix... 14.1V all day long.

If anyone needs a new-in-box starter let me know.