Patent ID: 8470481

Claim:
A power supply unit comprising: a fuel cell using methanol as fuel; a secondary battery for supplying power to a load; a fuel cell control part for controlling the amount of fuel and/or air supplied to said fuel cell; a power converter for converting the power output from said fuel cell to a predetermined voltage or current, supplying power to the load and/or said secondary battery; and a secondary battery residual capacity detector for detecting the residual capacity of said secondary battery, wherein said fuel cell control part has a plurality of power generation modes that each correspond to a range of residual capacities detected by the secondary battery residual capacity detector and a predetermined quantity of the fuel and/or air to be supplied to the fuel cell, wherein the fuel cell control part supplies the predetermined quantity of the fuel and/or air corresponding to a selected one of the power generation modes and maintains the predetermined quantity of the fuel and/or air supplied to the fuel cell over the range of residual capacities corresponding to the selected one of the power generation modes.