With a battery charger, I charged up the battery on my 90 Winter Car, to make sure it did not have to work too hard to recharge the battery. Started the car, and my battery light is on. Much to my surprise, when I put a gauge on it, the alternator was at 15 Volts at the idle speed. I swapped out the battery and the reading was the same. What goes on inside the alternator to begin the over-charging situation. I do not relish the removal of the alternator and going to a repair shop, so I am asking if there are any things I can do to get it to charge properly. Any ideas or advice is welcomed.