Question about 2005 BMW M3

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Own a 2005 BMW M3, car battery draining -battery less than year.

Own a 2005 BMW M3, new battery in last year. Garage kept during Chicago winters, but started occasionally. Recently battery won't hold charge (intermittent behavior), battery needs to be recharged before able to jump start. Was told by BWM that it is normal? Even with vehicle off, one of the supposed 8 computers was still showing a drain on the battery. Is BWM dealer telling truth or just want to avoid a costly computer chip replacement while under warranty? Could it be wiring harness or starter relays?

Posted by Anonymous on

  • Anonymous Mar 25, 2010

    I appreciate your response, but the battery is only 8 months old. Allegedly BWM said that one of the 8 computer chips was causing drainage; but then came back with the answer because the car hasn't been driven often enough. Even though it was not on the road except for a few days in our Chicago winters, it was started and motor running for awhile. Then all of of a sudden, it would have intermittent times when it did not want to start. Did purchase a battery charger and fully charged, guess time will tell; if we get stranded or not. Battery in trunk was indicating a different draw than the battery connections in engine of car too? Seems like lots of BMW's (models/makes) have been having similar battery issues. I was thinking it was more the battery cable/harness wiring, etc. You can only drain and recharge a battery so many times before it is useless. The car was purchased in 2006 and never had this issue in the prior years with lack of use; just out of nowhere. thanks again!



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Dave C

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From what you're saying here, I believe that you simply have a bad battery. Most batteries only last 5 years, much less if they're left to sit in storage periodically. You really should charge the battery overnight and do a load test on it the next day. The person(s) you spoke to at BMW were probably sales staff and not actual technicians. Costco has very good batteries at reasonable prices.

Posted on Mar 24, 2010

  • Dave  C
    Dave C Mar 24, 2010

    You may not like my answer, but after you need a battery.

  • Dave  C
    Dave C Mar 25, 2010

    Check the car at night to see if any interior lights are on. Even get someone to lay in the trunk when you close the lid and check for light. I really doubt the computer theory. Also, make sure all devices are unplugged from the lighter or power outlets.



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SOURCE: 2005 BMW M3 battery not holding charge, intermittently dead

install a battery tender this will mantain the voltage in the battery these work great and will not harm battery or car

  • Posted on Mar 24, 2010


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