A power system for a digital license plate includes a sensor, storage memory, and a battery status monitor operable only during operation of the digital license plate. The battery status monitor includes an analog to digital converter (ADC) connected to a battery to provide status data to a processor in the digital license plate, with status data being stored in the storage memory. A determination of battery lifetime being made at least in part using the status data and input from the sensor. In one embodiment status data can include external temperature.