Patent ID: 8450016

Claim:
A fuel cell system having a fuel cell for generating power by reaction of reactive gases and a scavenging means for introducing scavenging gas to the fuel cell after the fuel cell stops generating the power, the fuel cell system comprising: a water amount measuring means for measuring an amount of water in the fuel cell, the water amount measuring means comprising: a water amount estimating means for estimating the amount of water in the fuel cell, based on a predetermined relationship map between an integrated value of generated electric current by the fuel cell and an amount of water in the fuel cell, a power generation stop period measuring means for measuring a power generation stop period of the fuel cell, and an after-stop water amount estimating means for estimating a current amount of water in the fuel cell after the fuel cell stops generating the power, based on a predetermined relationship map between a power generation stop period and an amount of water in the fuel cell; and a scavenging period determining means for determining a scavenging period based on a predetermined relationship map between a current amount of water in the fuel cell and scavenging period.