Abstract: Exemplary temperature-adaptive battery charging systems can discontinue, or disable, charging of the rechargeable battery in accordance with various C rates, such as the C/40 rate, the C/20 rate, and/or the C/15 rate to provide some examples, in response to the temperature of the rechargeable battery. In some embodiments, the exemplary temperature-adaptive battery charging systems can discontinue, or disable, charging of the rechargeable battery in accordance a first C rate, such as the C/40 rate to provide an example, when the temperature of the rechargeable battery is within a first temperature range. The exemplary temperature-adaptive battery charging systems can dynamically adapt the discontinuing, or cutting off, of the charging of the rechargeable battery in response to the temperature of the rechargeable battery increasing and/or decreasing as the rechargeable battery being charged.

Abstract: The invention is a hydrogen passivation shut down system for a fuel cell power plant (10). An anode flow path (24) is in fluid communication with an anode catalyst (14) for directing hydrogen fuel to flow adjacent to the anode catalyst (14), and a cathode flow path (38) is in fluid communication with a cathode catalyst (16) for directing an oxidant to flow adjacent to the cathode catalyst (16) of a fuel cell (12). Hydrogen fuel is permitted to transfer between the anode flow path (24) and the cathode flow path (38). A hydrogen reservoir (66) is secured in fluid communication with the anode flow path (24) for receiving and storing hydrogen during fuel cell (12) operation, and for releasing the hydrogen into the fuel cell (12) whenever the fuel cell (12) is shut down.

Abstract: To mitigate bubble blockage in water passageways (78, 85), in or near reactant gas flow field plates (74, 81) of fuel cells (38), passageways are configured with (a) intersecting polygons, obtuse angles including triangles, trapezoids, or (b) hydrophobic surfaces (111), or (c) differing adjacent channels (127, 128), or (d) water permeable layers (93, 115, 116, 119) adjacent to water channels or hydrophobic/hydrophilic layers (114, 120).

Abstract: To mitigate bubble blockage in water passageways (78, 85), in or near reactant gas flow field plates (74, 81) of fuel cells (38), passageways are configured with (a) cross sections having intersecting polygons or other shapes, obtuse angles including triangles and trapezoids, or (b) hydrophobic surfaces (111), or (c) differing adjacent channels (127, 128), or (d) water permeable layers (93, 115, 116, 119) adjacent to water channels or hydrophobic/hydrophilic layers (114, 120), or (e) diverging channels (152).

Abstract: A PEM fuel cell power plant includes fuel cells, each of which has a cathode reactant flow field plate which is substantially impermeable to fluids, a water coolant source, and a fluid permeable anode reactant flow field plate adjacent to said water coolant source. The anode reactant flow field plates pass water from the coolant sources into the cells where the water is evaporated to cool the cells. The cathode flow field plates prevent reactant crossover between adjacent cells. By providing a single water permeable plate for each cell in the power plant the amount of water present in the power plant at shut down is limited to a degree which does not require adjunct water purging components to remove water from the plates when the power plant is shut down during freezing ambient conditions. Thus the amount of residual ice in the power plant that forms in the plates during shut down in such freezing conditions will be limited.

Abstract: A cascaded fuel cell stack (9a) includes a plurality of groups (10-12) of fuel cells (13) connected electrically in series by means of conductive separator plates (58, 59) and current collecting pressure plates (56, 57). Each group has an inlet fuel distributing fuel inlet manifold (17a, 19c, 20c), a fuel exit manifold (19a, 20a) of each group except the last feeding the inlet manifold of each subsequent group. A microcontroller responds to signals from a plurality of voltage sensing devices (48a-48c) to cause corresponding switches (50a-50c) (a) to connect each group, and all preceding groups in the sequence, to a voltage limiting device (VLD) (45), or (b) to connect each group to its own (VLD (45a-45c), in response to sensing a predetermined average cell voltage across the corresponding group. When normal operation occurs, the microcontroller connects the main load and disconnects the voltage limiting device (53) (25).

Abstract: Fuel cells (38) have water passageways (67; 78, 85; 78a, 85a) that provide water through reactant gas flow field plates (74, 81) to cool the fuel cell. The water passageways may be vented to atmosphere (99), by a porous plug (69), or pumped (89, 146) with or without removing any water from the passageways. A condenser (59, 124) receives reactant air exhaust, may have a contiguous reservoir (64, 128), may be vertical, (a vehicle radiator, FIG. 2), may be horizontal, contiguous with the top of the fuel cell stack (37, FIG. 5), or below (124) the fuel cell stack (120). The passageways may be grooves (76, 77; 83, 84) or may comprise a plane of porous hydrophilic material (78a, 85a) contiguous with substantially the entire surface of one or both of the reactant gas flow field plates. Air flow in the condenser may be controlled by shutters (155). The condenser may be a heat exchanger (59a) having freeze-proof liquid flowing through a coil (161) thereof, the amount being controlled by a valve (166).

Abstract: The invention is a hydrogen passivation shut down system for a fuel cell power plant (10). An anode flow path (24) is in fluid communication with an anode catalyst (14) for directing hydrogen fuel to flow adjacent to the anode catalyst (14), and a cathode flow path (38) is in fluid communication with a cathode catalyst (16) for directing an oxidant to flow adjacent to the cathode catalyst (16) of a fuel cell (12). Hydrogen fuel is permitted to transfer between the anode flow path (24) and the cathode flow path (38). A hydrogen reservoir (66) is secured in fluid communication with the anode flow path (24) for receiving and storing hydrogen during fuel cell (12) operation, and for releasing the hydrogen into fuel cell (12) whenever the fuel cell (12) is shut down.

Abstract: The invention is a hydrogen passivation shut down system for a fuel cell power plant (10). An anode flow path (24) is in fluid communication with an anode catalyst (14) for directing hydrogen fuel to flow adjacent to the anode catalyst (14), and a cathode flow path (38) is in fluid communication with a cathode catalyst (16) for directing an oxidant to flow adjacent to the cathode catalyst (16) of a fuel cell (12). Hydrogen fuel is permitted to transfer between the anode flow path (24) and the cathode flow path (38). A hydrogen reservoir (66) is secured in fluid communication with the anode flow path (24) for receiving and storing hydrogen during fuel cell (12) operation, and for releasing the hydrogen into fuel cell (12) whenever the fuel cell (12) is shut down.

Abstract: A cascaded fuel cell stack (9a) includes a plurality of groups (10-12) of fuel cells (13) connected electrically in series by means of conductive separator plates (58, 59) and current collecting pressure plates (56, 57). Each group has an inlet fuel distributing fuel inlet manifold (17a, 19c, 20c), a fuel exit manifold (19a, 20a) of each group except the last feeding the inlet manifold of each subsequent group. A microcontroller responds to signals from a plurality of voltage sensing devices (48a-48c) to cause corresponding switches (50a-50c) (a) to connect each group, and all preceding groups in the sequence, to a voltage limiting device (VLD) (45), or (b) to connect each group to its own (VLD (45a-45c), in response to sensing a predetermined average cell voltage across the corresponding group. When normal operation occurs, the microcontroller connects the main load and disconnects the voltage limiting device (53) (25).

Abstract: A fuel cell stack (10) includes a reaction portion (20) having an end cell (12) secured adjacent to a current collector (30). The collector (30) has a sensible heat no greater than a sensible heat of the end cell (12) and an electrical resistivity no greater than 100 micro-ohms centimeters. An insulator (40) is secured adjacent the collector (30) and has a thermal conductivity that is no greater than 0.500 Watts per meter per degree Kelvin. Because of the low sensible heat of the current collector (30) and low rate of heat transfer of the insulator (40), heat does not readily leave the end cell (12) resulting in a rapid heating of the end cell (12), thereby avoiding freezing and accumulation of product water in the end cell (12) during start up in subfreezing conditions.

Abstract: The invention is a hydrogen passivation shut down system for a fuel cell power plant (10). An anode flow path (24) is in fluid communication with an anode catalyst (14) for directing hydrogen fuel to flow adjacent to the anode catalyst (14), and a cathode flow path (38) is in fluid communication with a cathode catalyst (16) for directing an oxidant to flow adjacent to the cathode catalyst (16) of a fuel cell (12). Hydrogen fuel is permitted to transfer between the anode flow path (24) and the cathode flow path (38). A hydrogen reservoir (66) is secured in fluid communication with the anode flow path (24) for receiving and storing hydrogen during fuel cell (12) operation, and for releasing the hydrogen into fuel cell (12) whenever the fuel cell (12) is shut down.