Patent ID: 7579806

Claim:
A method for operating a battery pack cell adapted to be connectable to a load capable of being turned on and off; the battery pack comprising a fuel cell, wherein said battery pack is adapted to be connectable to a fuel container; the battery pack further comprising a control means for connecting the secondary battery to the heating element in the event of the sensed temperature being below a first predetermined level; wherein said control means is responsive to a temperature sensed at the temperature sensor, and is responsive to the condition of the load being connected or not, and is responsive to the condition of the load being turned on or not, and is responsive to the condition of a fuel container being connected to the battery pack or not, and is responsive to the event of a load being connected and being turned on, and is responsive to the event of a fuel container being connected to the battery pack; the method comprising the steps of: operating the fuel cell and charging a secondary battery therefrom, the fuel cell and secondary battery both within a housing; thereafter, sensing a temperature at the fuel cell; in the event of the control-means-sensed temperature dropping to a predetermined level, and in the event of a control-means-sensed fuel container being installed to the battery pack, and in the event of the battery pack being connected to a control-means-sensed load, and in the event of the control-means-sensed load not being off, connecting the secondary battery to a heating element in thermally conductive communication with the fuel cell, thereby warming the fuel cell.