Emergency battery

WARNING: This page is about a different car, the 2013 BMW X5, 2012 BMW X5, and 2011 BMW X5. However, it is still accessible from the selected car via links, so may be relevant.

The emergency battery is designed as a nickel metal hydride battery with 4.8 V and a capacity of 600 mAh. The emergency battery serves as a voltage source if the voltage supply of the vehicle for the TCB control unit basic version is interrupted due to an accident for example. In this case, an emergency call can be placed and the connection to the emergency center maintained for at least 5 minutes independent of the voltage supply in the vehicle.

The TCB control unit basic version monitors the emergency battery after every start-up as part of an internal self-test. The emergency battery has a service life of at least 5 years. If the capacity of the emergency battery is exhausted to the extent that placing an emergency call can no longer be guaranteed then this is shown by a Check Control message (emergency call system fault!). In addition, a fault code entry is stored in the TCB control unit basic version.