Battery in luggage compartment under floor trim panel
WARNING: This page is about a different car, the 2011 BMW 750xi, 2011 BMW 750Lxi, 2010 BMW 750xi, and 2010 BMW 750Lxi. However, it is still accessible from the selected car via links, so may be relevant.
Follow instructions for disconnecting and connecting battery.
Fold back floor trim panel (1).
Lift cover (2) on battery negative lead.
Disconnect and cover battery negative lead (3).
Release nuts (4).
Remove battery cover.
Courtesy of BMW OF NORTH AMERICA, INC.