Patent ID: 7745025

Claim:
A rechargeable power pack comprising: a. a fuel cell stack; b. a DC-DC converter coupled to receive the output of said fuel cell stack; c. a first battery and associated battery protection circuit; d. a second battery and associated battery protection circuit, and said DC-DC converter being coupled between the output of the fuel cell stack and a dual path, said dual path having power paths leading to each of said first and second battery; e. a system controller and balance of plant assembly configured to receive a signal indicative of a charge characteristic of each battery and to control operating characteristics of said fuel cell; f. at least one isolation circuit between said first and said second associated battery protection circuits, and between said first associated battery protection circuit and said system controller and balance of plant assembly; and g. a switch network defining one or more of said power paths, said switch network having: (i) a first set of switches associated with said first battery, including a pair of switches coupled across said first battery and associated battery protection circuit which, when closed, allows current to flow such that the fuel cell stack charges the first battery, and a third switch which couples the first battery to provide power to an associated load that is being powered by the rechargeable power pack, said first set of switches having at least one switch driver that is in turn powered by the first battery; and (ii) a second set of switches associated with said second battery, including a pair of switches coupled across said second battery and associated battery protection circuit which, when closed, allows current to flow such that the fuel cell stack charges the second battery, and a third switch in the second set of switches, which couples the second battery to provide power to the associated load, said second set of switches having at least one switch driver that is powered by the second battery; said controller being programmed to operate the sets of switches such that when one battery is powering the load, the other battery is being charged by the fuel cell, in non-fault conditions.