Abstract: An on-board fuel cell system adapted to be installed on a motor vehicle includes a main passage connecting a hydrogen-gas storage device with an inlet of a fuel cell, a circulation passage that connects an outlet of the fuel cell with a first point in the main passage, a pump disposed in the circulation passage, and a bypass passage that connects a second point between the outlet of the storage device and the first point, with a third point located in the circulation passage between the outlet of the fuel cell and the pump. During a normal operation condition of the system, the hydrogen gas flows from the storage device to the fuel cell through the main passage, and hydrogen gas discharged from the fuel cell returns to the main passage through the circulation passage.

Abstract: An inexpensive and corrosion resistant metal-made gas separator includes a base formed by joining formed stainless steel base sheets face to face. The base carries on each of opposite surfaces thereof a first coating layer formed by plating with tin. The base is also coated with a second coating layer of a thermal expansion graphite. When incorporated into a fuel cell, the separator contacts gas diffusion electrodes that are formed from a carbon material similar to the carbon material of the second coating layer, so that the contact resistance is reduced. The first coating layer is formed after a passive state coating is removed from the stainless steel surface, so that an increase in the internal resistance of the separator caused by the passive state coating is substantially prevented.

Abstract: A power supply system 10 with a stack of fuel cells 20 and a storage battery 30 includes a remaining charge monitor 46 for measuring the remaining charge of the storage battery 30. The remaining charge monitor 46 detects the remaining charge of the storage battery 30 at the time of stopping operation of the power supply system 10. In case that the remaining charge of the storage battery 30 is not greater than a predetermined level, the fuel cells 20 continuously charge the storage battery 30 until the remaining charge reaches the predetermined level. The power supply system 10 is stopped after the charging operation of the storage battery 30 has been accomplished. At a next start of the power supply system, the storage battery 30 functions as a primary power source to supply electric power to a loading until the warm-up of the fuel cells 20 is completed.

Abstract: A power supply system 10 with a stack of fuel cells 20 and a storage battery 30 includes a remaining charge monitor 42 for measuring the remaining charge of the storage battery 30. At the time of starting the power supply system 10, the remaining charge monitor 42 detects the remaining charge of the storage battery 30. The power supply system 10 estimates output electric current of the fuel cells 20 based on the observed remaining charge of the storage battery 30 and an amount of electric power required for auxiliary machinery 34, and supplies required amounts of gases to the fuel cells 20 based on the estimated output electric current.

Abstract: In a fuel-cells system 10 including a stack of fuel cells 20 and a storage battery 30, the remaining charge of the storage battery 30 is measured by a remaining charge monitor 46. In case that the observed remaining charge of the storage battery 30 is less than a predetermined reference value, a control unit 50 outputs a driving signal to an inverter 80, in order to restrict the consumption of electric power by a motor 32. When it is determined that the output state of the storage battery 30 is in the discharging state, based on the output electric current of the storage battery 30 measured by a current sensor 90, the control unit 50 further limits the electric power consumed by the motor 32. These processes are repeatedly carried out to charge the storage battery 30 and recover the remaining charge of the storage battery 30 to a sufficient level.