I've been getting High Battery Discharge on start up last few days. It does not pop up every time I start the car - maybe half the time. I have a 6 month old battery, and had it checked this weekend and it shows battery is good. Last time I had service, BMW checked my alternator and said it rated 9 out of 10. My 2007 530 has 124,000 miles.

If the battery and alternator are good, something must be draining the system. The car cranks up and starts with no issue. Yesterday I had to reset my time/date after start up.

Any thoughts?

 

battery connections for earth damaged or not connected fully?

 

I was getting random battery discharge warning. Although my battery was draining (down to about 5V). The battery positive cable which contains the battery monitor was replaced. The monitor was faulty and discharging the battery and occasionally telling the car no battery was present. Not a cheap fix - £90ish for cable and 1hrs labour.

 

Do you have comfort access? I had the exact same problem and it turned out to be a defective door handle with comfort access. Replaced and handle and no more problems.

Edit: I see in your sig you do have CA. I would check that out.

 

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Sounds like you may need to get a closed current draw test done first to figure out what's really going on? Too many parts involved that could go wrong and cause the drain.

 

124k miles on a 07? Must be a heavily used DD. How has the car held up in terms of reliability?

 

Could it be this? http://www.bmwtis.com/tsb/bulletins/...p/B610605g.htm

 

Thanks for all your responses. Per the suggestion, I checked the battery connections and ground, and all seem snug and clean. It's about the only thing I can think of to do myself, so I'll make an appointment with my dealer.

This is the first head scratcher I've had with the car, and hopefully something simple (or at least not expensive). This has been the most reliable and trouble free car I've owned (I'm 53 so there have been a few).

 

On the positive line there was nothing to visually inspect. The little black box was failing.

Try putting the car on charge (use the points under the bonnet). Get a meter and check the voltage accross the battery. If it is cycling and not really increasing i.e. voltage going high then dropping back to the original volage.

This would suggest the positive line is faulty.

Should of added there are loads of possible drains to the battery. Most common - confort access doors, heated wing mirrors, cd changer, car not going into full sleep mode.