2001 BMW 323i

Battery keeps going dead over night. Are there any well known location of the problem. I have ruled out Battery connections, alternator and common sense areas?
Need your help.
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mtyjoe wrote:

How old is the battery? Have you considered replacing it?
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Check for something electric that may be staying on. Trunk light, perhaps? Radar detector? Turn the car off and open all doors, hood and trunk and look for a light(s) that shouldn't be on. Maybe an audio amplifier? Powered subwoofer? I've done that one! :)

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Had this problem before. Disconnect the battery on one side and connect a voltmeter to bridge the gap from the battery to the cable. Start pulling fuses to see when the voltage drop stops. (be logical about this step) It's safe to have the fuse diagram handy to get the right amp fuses where they go.
Mine was a radio that was in "stand-by mode" instead of "off". I just popped the faceplate loose each time I left the car and it was fine.
Bill in Omaha 86 535i
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Some devices are always 'live' on a modern car, so this test wouldn't be conclusive. Use an ammeter and look for a total in excess of about 50mA which is the normal 'resting' current. Anything which takes out a good battery overnight will be drawing several amps and this isn't normal.
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*Ambition is a poor excuse for not having enough sense to be lazy *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Bill wrote:

I thought these models were designed so that the car goes to "sleep" after a certain period of being shut off? I had on occasion left a light on in my e46 and never found the battery to be dead. I would think that you still have the original battery and it is time for a new one!
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