Patent ID: 8298711

Claim:
A method of operating a fuel cell system which has a multi-cell fuel cell having a plurality of single cells connected to a fuel supplier, an electricity storing member, and a control unit connected to the fuel cell and the electricity storing member, the method comprising: a step of starting to supply power from the electricity storing member to the control unit and an external load connected to the, control unit when starting the fuel cell system; a step of detecting a power discharge amount of the electricity storing member; a step of starting to supply a fuel from the fuel supplier to the fuel cell when the power discharge amount of the electricity storing member reaches a predetermined power discharging amount that is equal to or greater than the amount of power provided from the fuel cell by consuming the fuel remaining inside the fuel cell after stopping to supply the fuel from the fuel supplier to the fuel cell; a step of supplying the power from the fuel cell to the external load by way of the control unit; a step of detecting the power discharge amount of the electricity storing member by restarting the supply of power from the electricity storing member to the external load by way of the control unit when a request for power from the load is equal to or larger than a maximum output of the fuel cell; a step of supplying the power from the fuel cell to the external load by way of the control unit and charging an electricity amount of an amount of a difference between a predetermined value and the power discharge amount to the electricity storing member when the request for the power from the load is less than the maximum power of the fuel cell and the power discharge amount of the electricity storing member is equal to or larger than the predetermined value; a step of starting to supply the power from the fuel cell to the control unit and interrupting. the supply of power from the electricity storing member to the control unit; a step of stopping to supply the fuel to the fuel cell when the external load is stopped; a step of continuing to generate power by the fuel remaining inside of the fuel cell using only a single cell of the multi-cell fuel cell simultaneously with stopping the supply of the fuel to the fuel cell; and a step of supplying the power generated by the remaining fuel to the electricity storing member by way of the control unit.