Abstract: According to embodiments of the invention, an operational method of a fuel cell is provided. The method includes providing a fuel cell used to provide output power to a load, measuring an initial average voltage of the output power provided by the fuel cell, measuring a first average voltage of the output power after the output power has been provided to the load by the fuel cell for a first time interval, and stopping the fuel cell from providing output power to the load when a voltage difference between the initial average voltage and the first average voltage is more than a first allowable voltage difference.

Abstract: A fuel cell system is provided. The fuel cell system includes a fuel tank, a fuel supply unit, a fuel cell stack, a liquefied recycling unit, a liquid level modulation unit, a sensing unit and a control unit. The fuel supply unit supplies a first fuel to the fuel tank. The fuel tank provides a second fuel to the fuel cell stack, and the fuel cell stack generates a first gas. The liquefied recycling unit liquefies the first gas, transforming the first gas into a recycled fluid. The liquid level modulation unit guides the recycled fluid into the fuel tank to maintain a stable fuel level of the second fuel in the fuel tank. The sensing unit senses a current signal provided by the fuel cell stack. The control unit calculates a current quantity according to the current signal to supply the first fuel to the fuel tank.

Abstract: A fuel cell system and a method for checking for hydrogen leakage are provided. The fuel cell system includes a fuel cell module having at least one fuel cell. The fuel cell system further includes a valve coupled to the fuel cell module and a hydrogen source for allowing hydrogen to be passed to the fuel cell module or blocking hydrogen from being passed to the fuel cell module. The fuel cell system further includes a controller board coupled to the valve and the fuel cell module for checking output voltage of the at least one fuel cell to determine whether there is hydrogen leak. The control board controls the valve for blocking hydrogen from being passed to the fuel cell module when the control board determines that there is a hydrogen leak.