# my battery keeps dying



## dodgerdave (Mar 20, 2010)

hello, i keep having a problem with my 01 325i battery dying. i've noticed that the fan has been going on and off on its own and sometimes stays on on its own even when the car is off and key is out. i even one time parked my car on saturday night (didn't notice a fan on, and always know when its on) and came back to it sunday afternoon and the fan was going and the car didn't have the juice to start. im wondering if anybody out there has a solution for me? i've heard maybe something about the f.s.u? please help i cant afford to take it to the shop to be screwed around on $$.


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## delmarco (Jan 2, 2009)

if your battery has not been changed in the last 5 years then it is time to change it.


which fan is this? the ac auxiliary fan?


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## dodgerdave (Mar 20, 2010)

*battery keeps dying.*

yes the battery was purchased august 07 brand new from the dealership. as for which fan im not sure. i don't feel air coming thru the vents when i have the problem. could it be the f.s.u. i've read about?


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## Kel (Mar 29, 2003)

The manual seems to say to charge it periodically. Some battery and tire places will charge your battery free of charge.


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## slbmw (Sep 2, 2009)

We had the same problem, guys on this forum told me what the problem was . Its the final stage resistor a easy fix well thats what i think . Good luck


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## stlbmw (Dec 2, 2008)

I would think it is the sensor/switch that tells the fan when to turn on. The dead battery is just a result of the botched
info from the switch telling the fan to turn on even though the car is not running. Run the fan without the car on and the alternator
charging things up and you'll draw the battery down until its dead.

stlbmw


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## vetsbmw (Oct 9, 2008)

It's definitely the motor resistor - I had the exact same problem. Fan kept running even when the car was off - battery would go every two days - I had to keep unplugging the battery every night for fear of not being able to go to work! Replaced the motor resistor after doing some research on this site. Cost me about $80 for the part and $40 for the labor. No More Problems!! Don't take it to the dealer - they will play dumb!!!! Trust me on this I'm a single woman with no car repair experience - you just got to be smart. Good luck.


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