PURPOSE: A telematics power managing system is provided to freely use a telematics function by always performing the telematics function after a user shuts off an engine. CONSTITUTION: A telematics control unit(120) checks the remaining level or discharge time of a sub battery(100). A charging control unit(130) charges the sub battery using a power supply unit. A vehicle unit(140) receives power from the sub battery and is controlled by the telematics control unit. The sub battery is repetitively charged and discharged. [Reference numerals] (100) Sub battery; (110) Power supply; (111) Main battery; (112) Charging unit; (120) Telematics control unit; (130) Charging control unit; (140) Vehicle unit
