Originally Posted by pimpernell

If I were you, when your finished with the car for the day, disconnect the battery until the next morning. The next day, reconnect the battery, and try and start the car. If it starts, the battery is holding its charge, if it doesn't, you know the battery is suspect. If the battery passes that test, I would recheck the alternator, by disconnecting all the wires attached to it, including the heavy battery cable, put your multi tester in continuity mode, and place one lead of the tester on the alternator battery connection post, and the other lead to the engine block or any ground point. If you get a continuity reading, it means that one or more of the alternator diodes have failed, and is allowing current to flow from your battery to the engine block. I had that happen to my car, and if the battery were left connected, it would totally discharge in a matter of a few hours with the key in the off position.