Let me just say up front that this question is about an alternator in a 1992 Pont Bonneville... but I own a Chevy, have been reading this forum for years so I know I'm going to get good info here... and I figure the problem and solution is related to the alternator and not the type of vehicle.
Battery with no load is about 12.7 volts. With engine running and no load the volts _slowly_ increase up to 13.9 volts. This takes about 7 seconds. With lights on, AC blasting, radio on, car stopped but in reverse and turn blinker on, the volts _slowly_ drop down to 12.7. This take about 15 seconds. Then over the period of about a minute, they drop down and stay at
12.3 volts.We had initially replaced the alternator but had the same problem. After that we found that the cables connected to the battery were very corroded. We cleaned them and then it appeared that the alternator might not have been the problem. This is when we had the original tested, they said it was fine (tested w/o a load) and we put it back in.
When I check my voltage (Chevy S-10!), it jumps right up to 14 volts and no matter what I do, I cannot get it to drop below 14 volts.
I'm under the impression that the regulator is built into the alternator. But even with the new alternator, the voltage slowly rose and fell. I'm under the impression before this problem started that it jumped right up to
14 volts and did not take several seconds.The replacement alternator was 105 amps. The vehicle does not have a heated windshield or defogger (it's in Florida). I connected a charger to the batter and set it at 10amps. The same readings mentioned above were obtained. I should have disconnected the battery and measured the voltage under a load but I overlooked this.
Any ideas on what the problem may be? What to check? I'm mainly wondering why the volts take so long to increase and decrease and why they drop to
12.3 under load.