Abstract: A hybrid type power source control system controls the output of a fuel cell, with disregard of the operation of the vehicle accelerator pedal, responsive to the detected amount of residual charge of the battery, which amount fluctuates as the vehicle travels. For example, the output of the fuel cell system 3 might be 3 kW when the residual charge is from 70% to 90%, 5 kW when the residual charge is from 70% to 60% and 10 kW when the residual charge is below 60%. Consequently, the fuel cell system 3 can generate power with an efficiency of from 30% to 33% and can charge the battery 1 effectively. Because the output of the fuel cell is fixed for each of the rather broad ranges of residual battery charge, thermal fatigue of the fuel cell is prevented because of little output fluctuation. When the electric motor is continuously operated, the fuel cell continuously charges the battery to maintain a fully charged stated, optionally with some allowance for fluctuation thereof.

Abstract: The fuel cell disclosed in the present specification is provided with an electrolyte membrane comprising a three-dimensional structure composed of bridged chains of a first polymer stable to water, and a second polymer having a function as an electrolyte. In such an electrolyte membrane, the bridged chains of the first polymer hold the second polymer, and hence the membrane does not swell with water. Furthermore, the electrolyte membrane can be properly designed depending on conditions required of the fuel cell, by choosing the first and second polymers.