NOVELTY - A fuel cell system has cathode inlet, cathode outlet, fluid connector, anode inlet, anode outlet, coolant inlet, coolant outlet, water transfer device, fluid conductor and cathode humidity valve. The fluid conductor is equipped with bleed valve and purge valve. The bleed valve and purge valve are controlled and regulated by differential pressure sensor. The water transfer device is equipped with water separation membrane, fluid level indicator, primary separator fluid outlet and secondary separator fluid outlet.    USE - As power supply for electric vehicles, especially to facilitate integration of the fuel cell system with the vehicle body (claimed).    ADVANTAGE - The freeze capable compact fuel cell system has improved humidification and removal of excess water and trapped nitrogen gas.    DETAILED DESCRIPTION - A freeze capable compact fuel cell system has plurality of fuel cells arranged in stack in which oxygen or oxygen-containing gas is reacted with hydrogen or hydrogen-containing gas, and generates electricity, exhaust gas-containing residual oxygen or residual oxygen and other gases and another exhaust gas-containing residual hydrogen or residual hydrogen and other gases. The system has gas passage of fluid connection between cathode inlet and outlet, other gas passage of fluid connection between integrated anode inlet and merged anode outlet, and fluid connection between coolant inlet and coolant outlet. The anode fluid connection is separated from cathode fluid connection by proton exchange membrane. The system further has water transfer device for receiving water and other gases from exhaust-gas in which fluid is connected with integrated merged anode outlet. The water transfer device has water separation membrane, fluid level indicator and separator fluid outlet and another separator fluid outlet. The fluid conductor is connected to primary outlet of water transfer device, and has bleed valve and purge valve. The bleed valve is controlled and regulated by differential pressure sensor in which the fluid connector is between cathode outlet and inlet. The purge valve is controlled and regulated by pressure sensor to vent excess anode fluid from system. The cathode humidity valve has fluid communication with secondary end of water transfer device at primary end, and fluid communication with cathode inlet at secondary end, and permits water flow from water transfer device to cathode inlet for humidifying cathode inlet.    DESCRIPTION OF DRAWING(S) - The figure shows the schematic bipolar PEM fuel stack and monitoring system.    Fuel cell (10)    Membrane electrolyte and electrode assembly (12)    Graphite block (18)    Anode (42)    Cathode (44)