A fuel cell including at least two stacks of electrochemical cells, a heat management system including a circuit for flowing a coolant into each of the stacks fed in parallel, and an outside circuit for flowing the coolant outside the stacks. The outside circuit includes a first subcircuit including a heat exchanger and a second subcircuit directly connected to an inlet of the inside circuit, and controlling valves for controlling flow of the coolant toward either or both subcircuits as a function of temperature of the coolant at an output of each of the stacks. The second outside subcircuit includes a mechanism increasing its head loss such that it is close or equal to that of the first outside subcircuit.