1996 GT Charging Issue
G'Day to you all,
I have a dilemma with the charging system in my Mustang. During normal daytime driving, my battery seems to stay charged (minimal load). I've monitored my volt meter and it stays (relatively) normal. At night I've noticed the volt meter slowly drops down to 8-10 volts or so. During this time I see the lights dimming, and the car runs a bit rough. It sometimes bounces back up to normal charging area, and then slowly progresses back down to 8-10 volts. Tonight this occurred and the car finally died, dipping below the 8 volt mark. Fortunately, it died near Wal-Mart and I was able to get another batter to get me home. With that being said, all the way home the volt meter stayed in the normal charging range all the way home, 40 miles.
Things I've done to fix the issue... I've purchased a new battery a couple of weeks ago (the same one that died tonight). I've replaced the negative cable as it was completely corroded from the battery terminal back from the previous battery. I've removed the alternator and took it to two different auto stores and had it tested and it came back as being "Good" at both (Autozone and O'Rileys). I assumed it was the alternator as I couldn't think of anything else that it could be???
Does anyone have any other ideas as to what might be causing this issue with my GT? I've done some searches and don't really find anything relating to this. My assumption is the Alternator/Regulator is bad, but I had it tested at two different parts stores? I did drive home tonight in 4th gear to keep the revs a bit higher (2500 compared to 1500). Again, the volt range stayed normal during the trip home, and prior to I was in 5th at 1500 RPM. Could it be the Alternator just isn't putting out enough power at 1500 RPM?
Any input would be great as I don't know where to go from here?