Method for determining if a fuel cell stack is overheating using stack end plate temperature sensors

A method for determining whether a fuel cell stack is overheating, said method comprising:

• measuring the temperature of a cooling fluid being output from the fuel cell stack using a cooling fluid outlet temperature sensor;
• measuring the temperature of end cells in the fuel cell stack;
• calculating an average end cell temperature based on the end cell temperature measurement;
• determining if any of the measured end cell temperatures are outlying temperature measurements by comparing each end cell temperature measurement to the average end cell temperature measurement;
• recalculating the average end cell temperature without the outlying end cell temperature measurements;
• comparing the measured cooling fluid outlet temperature to the average end cell temperature measurement;
• determining that the cooling fluid outlet temperature sensor has possibly failed if the measured cooling fluid outlet temperature is greater than the average end cell temperature measurement and the measured cooling fluid outlet temperature minus the average end cell temperature measurement is greater than a first predetermined temperature value;
• and
• determining that the fuel cell stack may be overheating if the average end cell temperature measurement is greater than the measured cooling fluid outlet temperature and the average end cell temperature measurement minus the measured cooling fluid outlet temperature is greater than a second predetermined temperature value.