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-   -   My Battery keeps dying for no reason?? (http://forum.e46fanatics.com/showthread.php?t=970897)

M3B4U 02-13-2013 12:34 PM

My Battery keeps dying for no reason??
Don't know why my battery on bmw e46 m3 keeps dying on me when I don't drive my car for 2 day. Can somebody can help me

YYCBMW 02-13-2013 02:49 PM


Originally Posted by M3B4U (Post 15158369)
Don't know why my battery on bmw e46 m3 keeps dying on me when I don't drive my car for 2 day. Can somebody can help me

Have your alternator checked. It's relatively cheap to do. Also, if it's an old battery, over 5 years, they can often times die, even if you haven't had any previous issues over the 5 years. My battery has been fine since 2005, so obviously it's not all batteries...

Also if you have drained that battery more than twice, typically batteries don't hold a charge worth crap after.

hope that helps!

M3B4U 02-13-2013 04:02 PM

I only had my battery for a year. Okay thanks ill check

YYCBMW 02-13-2013 04:06 PM


Originally Posted by M3B4U (Post 15159148)
I only had my battery for a year. Okay thanks ill check

I forgot to mention that you should have your battery checked because if the battery is fine, then that opens up a whole slew of other problems it could be.
Good luck!

Bmill160 02-14-2013 02:07 AM

Just went through this..

Where do you live? I travel a lot for work and regularly leave the car sitting M-F. Two weeks ago it was below 10 all week and when i got back the car wouldn't start but had power to run locks, lights, etc.

Can you drive around for 45+ minutes without problems? If so, google how to use the dash test on your alternator. The battery should be 12v+ with the car off, 13.7+ with it on. If both the above are true, probably not the alternator..

Next test the battery. Either take it to Autozone and they'll test for free, or if the battery isn't fully charged they'll want to charge it first before testing. Either give it to them for an hour or take it out and throw a trickle charger on the posts over night.

Let the battery sit (out of the car) for a day or two once charged and then drop it in and test it. If it works, you're good and it was just cold weather. If it doesn't, your battery isn't holding a charge and is cooked.

Last scenario is bad. If you charge it and let it sit and it goes in and works, the battery is fine. If it dies again after a day or two, you are leaking voltage and have a real problem.

Best of luck!

Sent from my DROID RAZR using Bimmer App

M3B4U 02-14-2013 06:26 PM

Just went and check my battery an they said it my alternator that I need to change. Thank you

YYCBMW 02-14-2013 07:00 PM

Did they test the alternator though? They can test it while in your car. That's good news (sort of) if its only your alternator.

Qstackfield 04-15-2013 09:37 AM

I woke up one morning and my battery in my Xi was dead, charged it and didn't think much of it.
Weeks later I went to the gas station, filled it up went to start and it was dead again. (Got a jump). I then took it to have the battery tested, it was fine.
It drove fine for weeks, then it died 3 times in a week. enough is enough, I dropped it off at the garage.
They couldn't find out what was wrong with it, took it home. Then that night around 3 am I walked past the car and the fan was running. BINGO!

Long story short. The relay or resistor went bad on the radiator fan, which cased the fan to kick on at random times and drain my battery.

BMWCaptain 04-15-2013 09:50 AM

Check your battery voltage when you stop the car and then test it before you start it 2 days later to see how much voltage is lost.

Do need to take your baytery.to get charged and test first. Advance Auto parts does a great job of charging and testing It.

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