Originally Posted by ard

Truck? Oh, you mean SUV.




(Sorry, pet peeve...)

BMWs really do some funny stuff with low voltages...enough to start, but then voltages too low for some modules, etc.... I am just guessing here, but first I'd trickle charge it. Disconnect the battery from the car for a while, charge it, reconnect. If it is a 4,5 year old OE battery I'd just replace it. It may NOT be the battery, but chances are you'll be needing one sooner or later. If it fixes it, great- if not you are looking at $$$ for a tow and diagnostics.

I usually buy the largest battery I can fit. I think yours is an AGM, so you will need to have the car's battery module 'reset', maybe reprogrammed if you change sizes.