I dunno... I have a 2004 car, a 530. I've had it for years now and never once had to plug it into anything.

 

I suspect that my high battery drain was initially caused by the car continually being opened by prospective buyers and the battery never got charged properly and was at the end of its useful life. One thing I learnt was that the high discharge warning was more likely if the car never got to sleep (in my case because it was a novelty when I first had it and I kept going in and playing around). Some parts of the car take a lot of current whilst it's awake so now I purposely avoid unecessary intrusions. And the weekly charge no doubt helps too. With previous cars I have had batteries lasting over 10 years but I suspect this would be too much to expect with the kind of goings on with the electronics in the E60/1.

See Rudy's thread #5 in another post about E60 "High Battery Discharge" for other causes.

 

I've also been told that if you have the 'comfort access' option, to lock the doors. This will ensure the car goes to sleep mode.

 

Other way around...when the car is sleeping, all lights are dark. When it's awake, the start/stop or "P" indicator is still on...

I've seen that posted here many times but still don't believe it's true. If the car is working properly, it should still go to sleep if it's unlocked. With CA, it should even go to sleep with the unlocked and the key inside.

 

What a silly thing for the tech to say. The Battery Tender sold by BMW is the only BMW-approved charger for our cars.

 

I can verify that my car goes to sleep normally locked or unlocked.

 

One would guess that BMW would only approve their brand of charger. My [un-approved] B&D cost about 1/3 of what I would have paid at the dealer parts counter.

sixcard

 

I'm not using a BMW battery tender. I'm using a Deltran Battery Tender Plus 12V @ 1.25A http://batterytender.com/automotive/...-at-1-25a.html

I'm assuming that BMW's battery tender is different?

 

I had read a while back that Deltran is the OEM manufacturer for the BMW tender. Don't know whether this is an accurate statement or not, but the BMW battery tender sure looks similar:

http://accessories.bmwusa.com/ItemVi...=6&subItemId=1

 

Probably just bein' generic ... not to use *any* kind of battery tender ...