Patent ID: 8736101

Claim:
A power source system for an electric powered vehicle equipped with a motor generating vehicle driving power, comprising: a main power storage device for storing electric power input to and output from said motor; a sub power storage device having an output voltage lower than an output voltage of said main power storage device; a voltage converter configured to convert the output voltage of said main power storage device to a level of the output voltage of said sub power storage device, and output the converted output voltage to said sub power storage device; and a first controller operated using electric power from said sub power storage device, for monitoring states of charge of said main power storage device and said sub power storage device and controlling operation and stop of said voltage converter, said first controller being configured such that, in a vehicle running state, said first controller is always operated, and always operates said voltage converter to maintain the output voltage of said sub power storage device at a target voltage, and when said electric powered vehicle is in a key-off state, said first controller is intermittently operated, and if the output voltage of said sub power storage device becomes lower than a prescribed voltage during operation, said first controller performs charging processing for said sub power storage device using the electric power of said main power storage device, by operating said voltage converter.