Patent ID: 8900768

Claim:
A fuel cell system comprising a fuel cell that generates electricity in response to supply of reaction gas, the fuel cell system comprising: a fuel cell comprising electrode catalyst; a voltage conversion device that changes output voltage of the fuel cell; a voltage detection device that detects output voltage of the fuel cell; a current detection device that detects output current of the fuel cell; and a decision device which is programmed to determine whether the electrode catalyst of the fuel cell is degraded or not, wherein during an activation treatment on the electrode catalyst the decision device is programmed to (a) temporarily stop supplying oxidation gas; (b) make a supply amount of the reaction gas constant; (c) change output voltage of the fuel cell while monitoring voltage detected by the voltage detection device; (d) detect a cyclic voltammetry characteristic of output current of the fuel cell detected by the current detection device, the output current changing associated with change of output voltage of the fuel cell; (e) calculate a value corresponding to an effective area of the electrode catalyst based on the detected cyclic voltammetry characteristic; and (f) compare the calculated value with a degradation decision value to decide whether the electrode catalyst is degraded or not.