A telematics unit is provided for a vehicle having a power unit, along with a method for controlling a telematics unit for a vehicle. The telematics unit includes a voltage sensor, a global positioning system unit, and a processor. The voltage sensor senses a measure of a voltage of the power unit. The global positioning system unit obtains position data as to a position of the vehicle. The processor is coupled to the voltage sensor and the global positioning system unit. The processor is configured to determine whether the voltage for the power unit has decreased using the sensed measure of the voltage, determine whether the vehicle is moving using the position data, and command the telematics unit to an off mode if the voltage has decreased and the vehicle is not moving.