An electrical power train for a vehicle, the power train comprising an electrical line (61), a fuel cell (3) connected to the electrical line (61), an electrical energy management unit (6) comprising a module controlling the fuel cell, a control device available to the driver of the vehicle for controlling deceleration of the latter, the control device being connected to the management unit, at least one electrical machine (4) connected to at least one driving wheel (40) connected to the electrical line (61) by means of an electronic module controlling the electrical machine, the electrical machine (4) being connected to a second cooling circuit (2) in which a cooling liquid circulates, independent of the first cooling circuit (1), an electrical dissipation element (8), and means for ordering the control module of the fuel battery to stop the process of producing electrical energy while connecting the said dissipation element (8) to the electrical line (61), in the event of a deceleration demand and when the management unit (6) detects that the power absorbed by the loads is less than the power sent over the electrical line (61).