I have a 3 month old 525i with about 3500 miles on it. About a month ago, it started to develop a problem where the battery drained overnight. A few weeks ago, I brought it in for service. They tested the car out, could find nothing obvious wrong with it and gave me a new battery on the theory that the battery may have been defective and developed a memory problem where it did not fully charge.

Now, three weeks later, the same problem recurs. I called my service center and he thinks the problem may be with the computer waking up overnight.

Has anyone else had a similar problem? If so, what was the resolution?

 

I dont remember the details but someone has posted something similar before - you should have a search through the forum.

 

I think the earlier posts were someone leaving the key in overnight while the car was parked in their garage. I assume that rfg17 is not leaving the key in as well, because that will cause the battery to drain. If not, there has to be either a software issue where the car is not going to sleep or is waking up like his dealer described, or possibly some other electrical issue/short that is draining the battery.

 

I don't think the key in the ignition was the problem, it was the software bug that causes the lights to come on if you open a (non driver's) door while the car was asleep with the key in the ignition and the headlight switch set to auto.

I leave my key in the ignition all the time in my garage and I never have a battery problem except for the software bug mentioned above...

 

Just to clarify: I do not keep my key in the car overnight. Also, on the previous service visit, they tested for obvious draws on the battery when the car was asleep and could not find any.

 

This was a big issue when BMW introduced the new 7. If no one here has a solution, perhaps you can serach out a 7 forum to see how the problem was fixed.

 

Here's a link to the previous thread that dealt with a similar situation:

http://forums.e60.net/index.php?showtopic=6878

edit: Ooops, I just realized that rfg17 started that thread too! Oh well, I guess the new battery didn't cure the problem, eh rfg17?

 

I had the problem. Flat batter in October. Flat in November. Flat in December.
Fix = software upgrade.
I left the car with the dealer when I went skiing and they had 7 days to fix it. They upgraded me just before Christmas and now I have not had a problem. I have left the car for 3-4 days and before longest was 2 days with flat. So I presume its fixed.
Apparently there was some sort of drain issue with earlier software versions (something like March to July 2004).

 

Do you know what CIP version it was? My car has a 9/2004 build date.

 

It was also a problem with E46's