Powering a fuel cell stack during standby

A method for maintaining a voltage of a fuel cell stack in a fuel cell system above a desired voltage value during a fuel cell system stand-by mode, said fuel cell stack including a plurality of fuel cells, said fuel cell system including a battery, said method comprising:

• monitoring the voltage of each of the fuel cells in the fuel cell stack;
• determining an average voltage of the voltages of each of the fuel cells in the fuel cell stack;
• determining a maximum cell voltage of the voltage of the fuel cell having the highest voltage;
• determining a minimum voltage of the fuel cell having the lowest voltage;
• determining whether the average voltage of the fuel cells in the fuel cell stack has fallen below a first predetermined voltage value;
• determining whether the maximum cell voltage is greater than a second predetermined voltage value;
• determining whether the minimum cell voltage is below a third predetermined voltage value;
• and
• applying a voltage potential to the fuel cell stack to increase the average voltage above the first predetermined voltage value if the average voltage has fallen below the first predetermined voltage value, wherein applying the voltage potential to the fuel cell stack includes applying the voltage potential to the fuel cell stack only if the maximum cell voltage is below the second predetermined voltage value regardless of whether the average voltage is below the first predetermined voltage value and applying the voltage potential to the fuel cell stack if the minimum cell voltage is below the third predetermined voltage value regardless of whether the average voltage is above first predetermined voltage value.

A control system with a controller programmed for maintaining a voltage of a fuel cell stack in a fuel cell system above a desired voltage value, said fuel cell stack including a plurality of fuel cells, said system comprising:

• means for monitoring the voltage of each of the fuel cells in the fuel cell stack that includes using a voltage monitoring circuit;
• means for determining an average voltage of the voltages of each of the fuel cells in the fuel cell stack that includes using the voltage monitoring circuit;
• means for determining whether the average voltage of the fuel cells in the fuel cell stack has fallen below a first predetermined voltage value;
• and
• means for applying a voltage potential to the fuel cell stack that includes using the controller programmed to use the voltage potential to increase the average voltage above the first predetermined voltage value if the average voltage has fallen below the first predetermined voltage value.