BATTERY STATE DETECTION DEVICE

PROBLEM TO BE SOLVED: To provide a battery state detection device capable of determining the state of degradation of a secondary battery, even if a current which is supplied from the secondary battery and is consumed in its electric load varies frequently. SOLUTION: The battery state detection device for detecting the state of the secondary battery 200 which supplies power to a portable device 300, includes: a voltage detection section 20 for detecting a voltage of the secondary battery 200; a current detection section 30 for detecting a charge/discharge current of the secondary battery 200; an arithmetic processing section 50 for calculating an internal resistance value of the secondary battery 200 on the basis of the voltage difference between voltages of the secondary battery 200 before and after a charging start detected by the detection section 20, and the current difference between currents of the secondary battery 200 before and after the charging start detected by the detection section 30, and determining the state of degradation of the secondary battery 200 on the basis of the calculated internal resistance value; and a communication processing section 70 for outputting a signal responding to the determination result in the processing section 50. COPYRIGHT: (C)2010,JPO&INPIT