Patent ID: 8524408

Claim:
A method for preventing a voltage potential reversal of a fuel cell in a fuel cell stack, said method comprising: determining a relationship between high frequency resistance and stack current density at which a fuel cell voltage potential reversal will occur for a predetermined type of membrane used in the fuel cells of the fuel cell stack; operating the fuel cell stack according to a power demand requested; determining the maximum cell resistance of the fuel cells in the stack; determining if the maximum cell resistance exceeds a predetermined cell resistance threshold value for the current at which the fuel cell stack is being operated where the predetermined cell resistance threshold value is based on the determined relationship between cell resistance and cell current at which a fuel cell voltage potential reversal will occur; adding a safety margin when determining if the maximum cell resistance of the fuel cells in the stack exceeds a threshold value for the current at which the fuel cell stack is being operated so as to ensure a reversal of the voltage potential of one or more of the fuel cells in the stack does not occur; and restricting the operation of the fuel cell stack by reducing the current if the maximum cell resistance exceeds the predetermined cell resistance threshold value.