Patent ID: 8728672

Claim:
A fuel cell system comprising: a fuel cell including a cell stack body in which a plurality of unit cells is stacked, the fuel cell generating electric power through an electrochemical reaction of a reactant gas which is supplied to the cell stack body; an output current control section programmed for temporarily increasing an output current of the fuel cell by reducing the voltage of the fuel cell to a voltage lower than the required voltage and taking out a current larger than the required current from the fuel cell while maintaining an amount of the reactant gas to be supplied to the fuel cell; a resistance component calculation section that is programmed to calculate a resistance component from an output current value and an output voltage value of the fuel cell being that of when the output current is temporarily increased by the output current control section; a moisture content calculation section that is programmed to calculate the moisture content in the fuel cell corresponding to the resistance component calculated by the resistance component calculation section; a moisture content determination section that is programmed to determine whether or not the moisture content calculated by the moisture content calculation section is equal to or lower than a dry state threshold value, which is for determining the dry state; and a moisture content increasing section that is programmed to perform a moisture content increasing process which increases a moisture content in the fuel cell, when it is determined by the moisture content determination section that the moisture content is equal to or lower than the dry state threshold value, wherein the output current control section is programmed to increase the output current of the fuel cell, whereby the current and the time are determined based on the amount of electric power that can be supplied by the remaining oxygen and the remaining hydrogen in a catalyst of the fuel cell.