Dead battery, a matter of time....

[3Series]

"Got a call this morning from the SA, who said they ran the diagnostic overnight and determined that the cause was "the parking lights were left on""

My theory on this is that the battery is weak and doesn't charge to 100%, but it charges high enough to not be "defective" or "dead".

So, if you leave your car door open for literally 5mintues, it will drain the battery enough where you will have problems and the car will say "parking lights left on". Unfortunately, I don't think it tells you how long they were left on.


The E60 forums has an actual PDF of the Energy Diagonostic procedure and the possible results that the tech reads.

"So, can service dept check the health of battery by some sort of a diagnostic? I should talk to them then. Last winter, car just didn't start with a blink. Before warranty expire, I might talk to SA to replace my battery."

Yes, but I bet they won't. They will run an Energy Diagnostic on the entire car. It will say if Comfort Access is draining your battery, the car isn't going into sleep mode or you don't drive enough to recharge the battery.

You can check the health of a battery yourself using a volt meter seeing how much voltage the battery if putting out when cold and also when the car is running with all the accessories on.