Patent ID: 8088524

Claim:
A fuel battery system comprising a fuel battery, a gas supplying device for supplying fuel gas and oxidant gas to the fuel battery, and an impedance measuring device for measuring impedance of the fuel battery, the fuel battery system comprising: an air compressor for supplying air which is the oxidant gas to the fuel battery; a key switch for instructing a start or a stop to the fuel battery system; and a controller for executing a film drying process based on an amount of water obtained by measurement of impedance when the key switch is switched OFF, wherein the controller changes an operation mode of the fuel battery from a low output mode to a high output mode upon detecting that that the key switch is switched OFF, so as to avoid an excessive state of the fuel battery in an estimated start-up time of the air compressor caused by the change of the operation mode, and executes the impedance measurement after detecting that the supply of air has been stabilized.