My 88 325ix began having a dead battery after sitting a few days. Thought the old Sears Diehard was finally going bad and bought a new Interstate Battery. I'm still having the same problem, I've checked the obvious, trunk and glove box lights not going out. Anyone have a clue as what else to look for?
Brad,
A start is to temporally wire in an ammeter (0-10 amps) and check the quiescent current. Anything over about 0.030 amps (30mA) requires checking, but if it's going flat in a few days it will be much more than that. So start on the 1-10 amp range and then use a lower one to get an accurate reading. If it's very high - more than 1 amp - start pulling out fuses and see if it goes lower. A reading of several amps might be a failed alternator diode - easily checked by disconnecting the alternator. Other possibilities are an aftermarket booster amp on the stereo not shutting down.
Sounds like you have a parasitic leak somewhere in your electrical system. My sister had the same problem in her 89 E30 and it turned out to be a continously running blower motor in her A/C system.
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