Battery Freezing
WARNING: This page does not describe the selected car, but rather 208 other vehicles, including the 2010 BMW Z4, 2010 BMW X6 M, 2010 BMW X6, 2010 BMW X5 M, and 2010 BMW X5. However, it is still accessible from the selected car via links, so may be relevant.
A fully charged battery can be stored at sub-freezing temperatures with no damage. The battery is protected from freezing to a temperature of -75° F. A fully discharged battery however will freeze at +27° F.
Avoid freezing by keeping the battery fully charged.
Carefully inspect a battery which has frozen for a cracked case.