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BMW Battery Drain

I just bought a 2008 BMW 535ia. I owned it four days before the battery died. I went back to the dealer I bought from and he told me that it was my fault – I didn’t drive the car enough. Said due to “advanced electronics” car has to be driven for at least 30 minutes each and every time other wise battery will continue to drain. Sold me a $60 charger and now I have to plug my car in all the time if I want it to start. Does this sound right? Obviously I want to unload this car as soon as my six month financing agreement expires, but am afraid to buy another luxury car – are they all like this now?

I work at home so I only drive the car three or four days a week,mostly for a 10 minute trip to town. I’m afraid to take this car anywhere. For me, luxury now means having a car that you know will start.

There are some considerations…If you’re going to start a car, you should at least drive it long enough to heat everything up and get rid of the moisture that will accumulate. 10 minutes should be enough, really, depending on ambient temperature, to do that, and charge the battery to pre-start condition. I used to be a BMW fan, but these kinds of horror stories have put me back to the good old 'Yota genre. Sounds like you’re being told a story, rather than them actually wanting to see if there’s something wrong.

I don’t want to go too far out on a limb, but I seriously, seriously doubt every BMW owner manages to get 30 minutes drive time every time they get in their car.

Maybe someone else here can chime in with a better reason. But for my .02, it doesn’t sound right.


“I owned it four days before the battery died…due to “advanced electronics” car has to be driven for at least 30 minutes each and every time”

He’s trying to get you out of his hair.
The charging system needs to be tested to confirm the battery is being properly charged when the car is running.
The battery drain current needs to be measured when the car is off.
With all those “advanced electronics” there’s more chance of something going wrong.

As a rule of thumb the battery voltage should be ~14V with the engine idling and all accessories off.
Battery drain should be less then 100 milliamps, under 50 even better.

Have any decent repair shop perform a “Parasitic Load Test” to isolate the problem and fix it…What the dealer told you is pure BS…BMW could not stay in business very long selling cars like that…

Thanks. Now I know specifically what to ask for at another shop.

I wonder about the dealer though. I made it pretty clear that I was unhappy. You would think they would have an incentive to try to find the problem, before I warn everyone I know not to buy a BMW. (too late now!)

Something else nags me about this – If I’m the only one having this problem, then why does BMW make a plug in charger?

As far as I know, they don’t actually make the charger. They may throw a badge on it, but the insides are almost certainly China born.

I wouldn’t be too hard on Beemers. It’s not the car, it’s the particular dealer you had. You may want to consider going back, and talking to someone higher up the food chain than the service adviser you were dealing with. You could try the service manager, and failing a decent result with him, even wander around and find a mechanic out having a smoke and chat with him. There’s really no reason you should put up with this on a car you’ve owned for just a little while…although you probably should have started this inquiry the day this all happened.

Best of luck, whatever route you choose.


Edit: If you have any paperwork, take it with you! You’ll want that evidence as backup.

The problem could be a defective blower resistor. This causes the blower to run even when the car is not running hence draining the battery

The dealer is lying to you. People have been kind of dancing around that. You can report him on Annieslist and

The story you were told about having to drive the car daily is bogus, at least on a car that is working properly. Most vehicles require a current drain on the battery of between 15 to 30 milliamps to keep things running. You should be able to park your car for a month without starting it and have enough battery charge to still start the car. I’m sure BMWs are no exception to this and if they were there should be something mentioned in the Owner’s Manual about the issue.

There may be a problem with the battery as it may be the original one and is getting near the end of life. It sounds like the dealer didn’t do a load check on the charging system as they should have done. This will check the system to see how the alternator and battery are working. My guess is you may need a new battery at least. That will give you better storage capacity so the starting will be easier. The current drain on the battery needs to be checked also to verify there isn’t a problem there. I recommend you take the car back to the dealer service and have them check those things out. Especially if you have a service warranty through them. They need to do their job correctly and not give you a line about being your fault and selling you more things.

Thanks all. I asked (actually demanded) that the service person put in a new battery but he talked me out of it saying that it wouldn’t help.

I have a service appt. tomorrow and I’m printing these comments out and taking them with me. Then I’m going to another service dealer.

You really should have a load test done before changing anything out. The test will show what is having a problem if there is something to be concerned about. The shop should also check the current drain on the battery while the systems are in the ‘sleep’ mode to make sure the current drain is within specs.

Caddyman has the right first step in my opinion. Start trouble shooting with a meter as he described.