TECHNOLOGY FOCUS - ELECTRONICS - Preferred Power Supply: The power supply comprises a set of the fuel cells, each fuel cell comprising a generally longitudinally elongated cylindrical lithium iron phosphate battery, the batteries being housed in a generally longitudinally aligned and hexagonally packed orientation. The charging circuit electrically communicates with a first thermal cut-off switch operable to interrupt flow of the charging current on the occurrence of a first pre-selected minimum threshold temperature. The first threshold temperature is selected at about 75 degrees C. The switching power circuit electrically communicates with a second thermal cut-off switch, operable to interrupt flow of the back-up current on the occurrence of the threshold temperature. The charging current comprises a DC current. The power supply as well comprises at least one fusible conductor electrically connecting a set of the fuel cells in series, the fusible conductor including a current interrupting member operable to interrupt current flow therepast in the event of a pre-selected triggering condition. The current interrupting member comprises a low temperature thermal fuse, and the triggering condition comprises a minimum threshold temperature selected at about 75 degrees C. The potting material comprises essentially silicone. Alternatively, the power supply for supplying back-up power during a power-out event comprises: a housing, an electrically insulating potting material, a fuel cell array comprising a set of fuel cells for supplying a back-up current during the power-out event, each fuel cell being disposed within the housing and substantially encased within the potting material, at least one conductor bridge electrically connecting a set of the fuel cells in series, the connector bridge including at least one current interrupting member which is actuable to interrupt current flow in the event of a pre-selected triggering condition, a charging circuit electrically connected to a first the fuel cell and an external power source for providing a charging current to the first fuel cell during normal power-on conditions, and a switching power circuit electrically connecting the fuel cell array and a power supply output for outputting the backup current during the power-out event. The conductor bridge includes two of the current interrupting members, a first the current interrupting member comprising a low temperature thermal fuse actuable to interrupt current flow along the conductor bridge on a minimum triggering temperature selected at about 75 degrees C, and the second other the current interrupting member comprising a high temperature fuse actuable to interrupt current flow along the conductor bridge on a minimum triggering temperature selected at about 130 degrees C. The fuel cells each comprise a generally cylindrical fuel cell for supplying a backup current during the power-out event, the fuel cells being disposed in an orientation selected from a generally square packed orientation and a generally hexagonally packed orientation to define longitudinally extending interspaces between it. The fuel cells are electrically connected in series, the first and second current interrupting members being disposed within a selected one of the interspaces. The charging circuit electrically communicates with a first thermal cut-off switch operable to interrupt the charging current on the occurrence of a pre-selected minimum temperature selected at about 150 degrees C, and preferably at least about 130 degrees C. The switching power circuit electrically communicates with a second thermal cut-off switch operable to interrupt flow of the back-up current on the occurrence of the pre-selected minimum temperature selected at about at least 150 degrees C, and preferably at least about 130 degrees C. The potting material comprises essentially silicone. Each fuel cells comprises a sealed lithium iron phosphate battery. The fuel cells are spaced from a next adjacent fuel cell by a minimum distance selected at between about 0.5 and 3 mm. The lithium iron phosphate battery each comprises a sealed rechargeable battery having a voltage selected at between about 2 and 5 volts, and preferably about 3 to 4 volts. In a second alternative case, the power supply for supplying backup power during a power-out event comprises: a housing, an electrically insulating silicone potting material, at least one fuel cell array comprising a set of electrically rechargeable lithium iron phosphate fuel cells for supplying a backup current during the power-out event, the fuel cells being generally of equal size and disposed in an aligned and hexagonally packed orientation to define longitudinally extending interspaces between it, the fuel cells being electrically connected in series and disposed within the housing substantially individually encased within the potting material, at least one conductor bridge electrically connecting a set of the fuel cells in series, the connector bridge including at least one current interrupting member which is actuable to interrupt current flow in the event of a pre-selected triggering condition, a charging circuit electrically connected to a first one of the fuel cell and an external power source for providing a charging current to the fuel cell array during normal power-on conditions, and a switching power circuit electrically connecting at least one the fuel cell and a power supply output for outputting the backup current during the power-out event. The power supply comprises a set of the conductor bridges, a selected one of the current interrupting member of each conductor bridge being disposed in an associated one of the longitudinally extending interspaces. Each of the set of fuel cells are spaced from a next adjacent fuel cell by a minimum distance selected at between about 0.5 and 3 mm. The power supply includes four the fuel cell arrays, each fuel cell array comprising between 6 and 10 the fuel cells. The power supply comprises at least four of the fuel cell arrays, each fuel cell array comprising between 5 and 12 rechargeable batteries. The housing comprises a substantially sealed housing, where the housing comprises a sealed stainless steel housing, and further including a heat sink for transferring thermal energy from at least one of the fuel cell arrays to an exterior region of the housing. The silicone potting compound has a specific gravity selected at between about 0.8 and 1, and preferably about 8.2 to 8.4. The charging circuit and switching power circuit are substantially encapsulated within the potting material.