A crash notification system (12) has a main battery (58) and a backup battery (60). The main battery has a main battery voltage and the backup battery has a backup battery voltage. A telematics control unit (16) senses the voltage of the main battery and receives an emergency notification signal from a restraints control module (18). In response to a change of state of the emergency notification signal and the main battery dropping below a predetermined battery the backup battery may be used. In addition, if an SOS button (52) is employed in the system, and the main battery voltage drops below a predetermined voltage the backup battery (60) may also be used.