Patent ID: 6960401

Claim:
A purge system for a fuel cell stack, comprising: a purge valve to regulate flow from the fuel cell stack; an actuator coupled to open and close the purge valve; a purge cell voltage sensor coupled across at least one fuel cell forming a purge cell portion of the fuel cell stack to determine the voltage across the purge cell portion; a fuel cell voltage sensor coupled across at least two fuel cells in the fuel cell stack to determine the voltage across the fuel cells; and a controller coupled to provide control signals to the actuator to open the purge valve when an average voltage across the purge cell portion of the fuel cell stack falls below a defined first percentage of a threshold voltage measured across the at least two fuel cells wherein the controller is further coupled to provide control signals to the actuator to close the purge valve after a determined purge duration has elapsed, the determination of purge duration being based on a flow of current through the fuel cell stack wherein the controller is further coupled to provide control signals to the actuator to close the purge valve when the average purge cell voltage rises above a defined second percentage of the average fuel cell voltage and wherein the defined second percentage is different than the defined first percentage.