Patent ID: 7846598

Claim:
A method of stopping operation of a fuel cell system, said fuel cell system comprising a fuel cell operated for power generation by reaction of a fuel gas supplied to an anode and an oxygen-containing gas supplied to a cathode, and an energy storage for assisting the output of said fuel cell, said method comprising the steps of: detecting a power generation stop signal; determining whether said energy storage stores energy of a sum of energy required for starting a next operation of the fuel cell system and energy required for performing a scavenging process of said anode when said power generation stop signal is detected; continuing said power generation of said fuel cell to charge said energy storage if said energy storage does not store the energy of the sum of the energy required; starting a scavenging process by supplying the oxygen-containing gas to said anode if said energy storage stores the energy of the sum of the energy required; monitoring the remaining electrical energy stored in said energy storage after starting said scavenging process; and finishing said scavenging process when the monitored remaining electrical energy is decreased to a remaining electrical energy threshold that is sufficient for start-up of the fuel cell at a next start-up operation.