Fuel cell system freeze-start systems and methods

A method for heating a dual stack fuel cell system of a vehicle, the method comprising:

• receiving a heat power request from a first fuel cell stack;
• receiving a first temperature of the first fuel cell stack and a second temperature of a second fuel cell stack;
• determining a first thermal state of the first fuel cell stack using the first temperature and a second thermal state of the second fuel cell stack using the second temperature;
• initiating, responsive to the first thermal state being a frozen thermal state and the second thermal state being an operable thermal state, a freeze-start thermal operating mode for the first fuel cell stack;
• and
• transferring, during the freeze-start thermal operating mode for the first fuel cell stack, heat from the second fuel cell stack to the first fuel cell stack.

A method of heating a dual stack fuel cell system of a vehicle, the method comprising:

• receiving a first temperature of a first fuel cell stack and a second temperature of a second fuel cell stack;
• determining a first thermal state of the first fuel cell stack using the first temperature and a second thermal state of the second fuel cell stack using the second temperature;
• and
• commanding, responsive to a determination that the first thermal state is a frozen state and the second thermal state is a frozen state, a first valve to an open position to enable heat transfer from a brake resistor to the first fuel cell stack.