Battery light comes on intermittently

sam48is · #1 02-18-2009, 02:04 PM

It started happening yesterday. Sometimes when I'm driving the red battery light comes on for a few seconds then goes away.

I should mention that the battery seems OK because the car always starts normally with no hesitation. Someone told me it could be the alternator.

Any ideas?

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sam48is · #2 02-20-2009, 02:03 PM

Okay now the light is coming on more often and for longer, but still goes out after a while then comes back on.... Starting to get worried...

Any ideas???

primetime · #3 02-20-2009, 02:19 PM

Its the begining signs of telling you that the alternator is about to go out. Get it looked at and mention that. If you keep going its going to shut off while you're driving and you'll have no power in the middle of the highway or road..take your pick.

sam48is · #4 02-20-2009, 02:46 PM

what happens if the power goes out while I'm driving? Won't the battery last a while?

NOVAX5 · #5 02-20-2009, 02:49 PM

get your battery check immediately, check voltage on alternator as well. you dont want to be in the situation we (me and my wife) were. she was left stranded on middle of I-95 when everything shuts down. she told me it was scary experience. the thing just shut down, i mean everything. she was lucky enough to pull over the shoulder of high speed traffic I-95. thats because in the morning she forgot tell me that the battery light is on, she took it to work and on the drive home the alternator died and the batter is gone too, that causes the whole thing to shut down. drive carefully.

sam48is · #6 02-20-2009, 02:52 PM

wow, that is scary... i'll have it checked out right away, although I've been driving it and everything seems normal... engine powers up with no hickups so I know the battery is (still) good.

What sucks is that the warranty ran out last month!

primetime · #7 02-20-2009, 03:00 PM

Battery won't be good for long. Trust me..That thing's gonna be dead in less then 5 days..And if you're lucky, it won't die while your driving..I'd be surprised if it lasted that much longer. In fact, I wouldn't drive it at all. If you do have to drive it, I'd drive it strait to the shop and nowhere else.

MATTYP · #8 02-20-2009, 03:25 PM

I had this problem, my light is still on, changed the voltage reg. The light is still on, I checked the charging rate and it is 14volts. I have run out of idears now

fast4d · #9 02-20-2009, 07:24 PM

after I installed a new alternator the light kept coming back on. had to take it to the dealer where they reset something.

01 BMW_X5 · #10 02-20-2009, 08:20 PM

Quote:

Originally Posted by MATTYP

I had this problem, my light is still on, changed the voltage reg. The light is still on, I checked the charging rate and it is 14volts. I have run out of idears now

Did you check and clean the contact surfaces for wear before you replaced the regulator?
Replacing just the voltage regulator won't solve the problem if there is an open circuit in the positive/negative or exciter diode.
You will have to replace the alternator if these conditions exist.
Get the alternator tested or if you have access to an oscilloscope, check it yourself.

As far as a reset, our resident BMW technician could tell you more on whether it is just to clear code using a generic OBD11 or if has to be on GT1/MoDIS.

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