Quiescent current consumption is in the range between 500 mA and 1000 mA - AF54.10-P-6400-03T

Possible cause of fault: 

The COMAND module (A40/3) with version 3.6 can cause a quiescent current of up to approx. 900 mA.

Measures: 

Install COMAND module (A40/3) with version 3.7.3 or higher.

At a quiescent current greater than 500 mA, the battery control module (N82) remains permanently "awake" and requires approx. an additional 80 mA for this purpose.