Patent ID: 8507141

Claim:
A method for correcting an estimation of nitrogen in an anode side of a fuel cell stack, said method comprising: estimating an amount of nitrogen in the anode side of the fuel cell stack using a model; shutting down the fuel cell stack; continuously measuring the pressure of an anode sub-system after shutdown of the fuel cell stack until the pressure in the anode sub-system is at approximately atmospheric pressure; determining if the pressure of the anode sub-system has reached approximately atmospheric pressure at a faster rate than the time necessary for the anode sub-system to reach approximately atmospheric pressure after a previous shutdown or calibrated time value; and correcting the estimation of nitrogen in the anode side of the stack if the pressure in the anode sub-system reached approximately atmospheric pressure at a faster rate than the previous shutdown or calibrated time value, wherein the correction of the estimation of nitrogen is proportional to the difference in time required for the anode sub-system to reach atmospheric pressure compared to the previous shutdown or calibrated time value.