I have a 1985 380SL which has been giving me problems, many problems. Today it is the ABS light which is always on! Along with the light the battery goes dead within 24 hours. I have had two new Interstate batteries that went dead and then would not recharge (gave a 'Fault' on the charger). I now have the battery disconnected while I look for an answer. I noticed, using a voltmeter, that when I turn off the engine the voltage starts to drop. I can see the reading go down about 0.1 or 0.2 volts every minute or so.
What the heck has happened?

Thanks for any clues.

Bob Chapman