General notes on disconnecting battery

WARNING: This page is about a different car, the 2013 BMW 550i GT, 2012 BMW 550i GT, 2011 BMW 550i GT, and 2010 BMW 550i GT. However, it is still accessible from the selected car via links, so may be relevant.

Do not disconnect battery leads and leads from alternator and starter motor while engine is running.
Vehicles with IBS on battery negative terminal:
Do not under any circumstances pull/lever off pole shoes by force.

Do not under any circumstances release socket-head cap screw of IBS.
Disconnect terminal of BATTERY NEGATIVE LEAD from vehicle battery. Cover battery negative terminal(s) and secure.
When work is carried out on the electrical system, faults may be caused in the fault memories of some control units when the battery is connected.
When installing battery terminal: Tightening torque 61 21 1AZ .