[xDrive50i]

It's NOT the USB you left plugged into the center console. I have a 64GB USB Flash drive plugged into the center console since I got the car (back in June of last year) and never had an issue with the battery.

You need to take a look some of the following:

1) how often do you drive the car?
2) what's the distance you travel each time?
3) do you use battery power after you arrived at your destination (e.g. you drive and drop someone off and wait in the car with the engine turned off but you listen to the radio, etc)?
4) do you move the car often without really driving it (e.g. start the car to move it to a different location like from one place to a different one in your driveway)?

3 and 4 above will quickly discharge your battery to the point where you will end up with the "Increased Battery Discharge" warning! If you don't drive the car far enough, the battery will not have enough time to recharge to a point where it can sustain all of the electronic that keeps drawing power from it especially during the time the car is not being driven!