After leaving car with dealer for 4 days the best explanation for battery low/draining was due to "old software". The service manager does not think the old software was the problem either. Considering nothing changed in my driving habits from 1 year ago. BMW NA made them run diagnostic after diagnostic with same result that there was a fault in the parking brake system or the control module was coming on when the car was off. Loading new software made the fault go away so there is nothing more they can do until the next time the warning light comes on.
As far as replacing the battery, BMW NA would not approve as the software update made the fault go away. I will give it a week or two to see if the fault reappears. If so I will call Germany if I need to. Getting concerned about what happens when the warranty is over. Maybe I better invest in an extended one.......
2011 550i xDrive, Imperial Blue Metallic/Oyster & Black Nappa, ZAV, ZCW, ZMP, ZP2, 2TB, 337, 465, 610, 6NF and 6WA. Worth the wait!