I drive a 1995 3.1L V6 Pontiac Grand Am SE.
I’ve been disconnecting my battery often to work on my car. I’ve had a lot of problems with it shutting off on me while driving but after replacing all 3 ignition coils and the crank sensor it seems as though I’ve fixed the problem.
In the process of fixing the problem of shutting off, I had a mechanic replace the alternator. It kept shutting off, so I had the crank sensor replaced because it was throwing a code. It stopped shutting off, so the first mechanic was nice enough to take the alternator off and give me a refund for it when he changed my brakes. With both the replacement alternator and the original/now-installed alternator (which was put in about 2 years ago with a new battery), the voltage gauge on the dash is running high (about 15.5 volts). Before it ran at a steady 13 volts and though the gauge is about 1-2 volts from the red zone, I don’t want to be constantly overcharging my battery. I’ve been told that the voltage regulator in the alternator may be bad, but I find this unlikely considering I noticed the high voltage with both the new and the old alternator.
My understanding is that when the key is in the “ON” but not “START” position, the dash voltage meter reads the battery’s voltage, but when the car is running it reads the alternator’s voltage output. Is this correct?
When it’s reading the battery’s voltage it reads about 11-12 volts. Then when the engine is running it reads about 15-16. 17-18 is the red zone, so that’s why I’m worried. Do you think that the alternator is putting out more voltage because the battery voltage is low before starting (not sure if 11-12 volts is low or not)?
What else could be causing this besides a voltage regulator?
Also: I plan to take it to AutoZone to get the battery and alternator checked but I won’t have the chance to do so for a few days, so some ideas in the mean time, would be much appreciated.