This one has got me baffled. Its my dad's car and I've gone through 3 new batteries from PepBoys. They are Eveready batteries size 49D. Each time it goes dead, I take it in and they do a load test, fully recharge it and it tests out fine. I reinstall the fully charged battery and it lasts a few days then dies again. Jumping it and running the car for an hour seems to charge the battery a little bit but its dead the next day.

The really weird part is that when I take the battery back an exchange it for a new one, it lasts about 3-4 months then its the same thing again.

We've taken the car in and the charging system checks out fine. My only guess is that its an intermittent problem probably with the alternator (brushes, regulator, ??)

Any ideas would be appreciated. My dad is so frustrated he wants to get rid of the car which I can't bear to see happen.

-Chris
'88 535is
'73 2002tii