i have a 1995 300e had the alternator rebuild 3 wks ago started fine but the charge battery light came on when first cranked then went off. Last week it would not start but would turn over charged battery was under 50% started fine for a few days. happened again took back to repair shop they tested it said it was not the alternator but the battery bought a new battery started fine that day and night. next morning would not start battery was again under 40%. Any ideas