I am having some funky electrical fluctuations on my volts gauge. Can somebody help me out? I just got the car out from winter storage and was driving around and I noticed that the volts wihile cruising would go as high as 15 to 15.5 volts and when I would stop at a light it would drop down to around 12 volts. I went home and charged the battery for 8 hours just to get it good and charged and drove it again and the same thing happened. My main concern is too much volts. And what happens in summer when I have my electric fan on and radio and headlights at night? I run an MSD box, electric fan and relay, also I installed a 100 amp alternator last year too. I still have an external voltage regulator that who knows how old it is. Could this be the culprit?

Last week I noticed a voltage problem too, my battery was bubbling over (I was getting 15.5 amps to it)!I changed the voltage regulator and things got normal again, plus all my lights are brighter and my turn signals blink faster. Hope that works for you. I think they are like 22 dollars from AC Delco

Most lead acid batteries top out at around 15 volts under heavy charge. Your readings are consistant with a high rate of charge so the voltage regulator is highly suspect.

It's also possible that you've got a bad connection somewhere in the charging circuit causing the regulator to misread the system voltage and command the over-charge. Often, though the bad connection is inside the VR.

-dnult

Bet it's the regulator. Had the same exact sounding problem and also had the boiling-over battery problem. Took the cover off the voltage regulator and found one side of the contacts had welded itself shut and also a burned wire. Replaced it and all is well.

I remember my dad having some contact burnishing files. He is an electronics tech and used them to maintain relays. He used to burnish the contacts on those old voltage regulators when they'd start acting flaky. But over time, he would have to do it every few weeks and eventually replaced them.

-dnult

Let me say this. Replace the voltage regulator everytime you change the alternator. I learned the hard way after burning up half of my harness. It is only like $14 investment that could save you hundreds.