A data compression system has been constructed with software and hardware specific to the electric vehicle (EV). The system and sensors are described. The system is modular and consists of a signal condition board, an analog to digital conversion board, a 16 bit microprocessor and an integral tape recorder. The microprocessor forms a trip histogram consisting of a map of average electrical and mechanical power, average velocity and time based on vehicle mechanical power and velocity intervals. Regenerative braking energy is distinguished. Temperature, voltage, current and power extreme parameters are recorded with time. Discharges are recorded based on battery depletion or at charge initiation. Charge parameters are sampled every three minutes. A tape should last one month in typical EV operations.