This question isn't exactly related to my mustang but on my winter driver the battery keeps going dead. I work third shift so it is dark on my way to work and on the way home. I can leave for work with a charged battery but by the time I get home it is dead. I tested the alt with a multimeter and it is puttin out the correct voltage and I just bought the battery 2 weeks ago and had it retested when this started to happen. The car runs as long as I don't turn it off even when the battery is dead but the headlights are very dim and the other electricals fail. Any suggestions?