Abstract: A concentration detector is adapted to detect the concentration of a liquid fuel in a container. The concentration detector comprises a rotating mechanism positioned underneath the level of the liquid fuel and having a rotational center. A first float having a specific gravity less than the specific gravity of the liquid fuel, a volume equivalent to “V” and a mass equivalent to “M”. The distance between the mass center of the first float and the rotational center is “L”. A second float connected with the first float and having a specific gravity less than the specific gravity of the liquid fuel, a volume equivalent to “V” and a mass equivalent to “r*M”. The distance between the mass center of the second float and the rotational center is “L. The mass center of the second float, the rotational center and the mass center of the first float constitute an included angle of 120°.

Abstract: A concentration detector is disclosed, which is adapted to detect a concentration of a liquid fuel in a container. The concentration detector includes a rotating means positioned underneath a level of a liquid fuel and rotatable at an angle ? on a X-Y plane. The rotating means includes at least three floating objects connected with each other. Each floating object has a specific gravity less than a specific gravity of the liquid fuel ?. The floating objects are balanced according to a torque equation, F(?,?)=0, such that the rotating means is still under the level of the liquid fuel. While a concentration of the liquid fuel is changed and the angle ? of the rotating means is detected, the specific gravity of the liquid fuel ? is obtained from the torque equation, F(?,?)=0, and thereby computing the concentration of the liquid fuel.

Abstract: A fuel cell device capable of adjusting operational parameters is disclosed, which includes fuel cell boards, an anode regulator, a cathode regulator, an anodic fuel supplier, and a control circuit. The fuel cell boards include an electrically connected interface to communicate status signals generated by the fuel cell boards during operation. The anode regulator is connected to the anodic fuel inlets and the anodic fuel outlets of the fuel cell boards and provides anodic fuels with predetermined parameters. The cathode regulator adjusts an amount of cathodic fuels supplied for cathodes of the fuel cell boards. The anodic fuel supplier is connected to the anode regulator and contains anodic fuels.

Abstract: A method for controlling an output power of a fuel cell is disclosed. A DC converter and a fuel cell are provided, and a voltage input end of the DC converter is connected to a voltage output end of the fuel cell. The DC converter is used to convert an input voltage of the fuel cell into a regular output voltage. The DC converter is also used to retain a voltage of the voltage input end of the DC converter within a predetermined range, and thereby an output voltage of the fuel cell is maintained within the predetermined range. The predetermined range of the voltage is set according to a number of membrane electrode assemblies in the fuel cell and a voltage of the membrane electrode assemblies generated in an extent of optimal power.

Abstract: An electrical circuit interface board for connecting a fuel cell is described, which includes a substrate, an electrical circuit, a first interface, and a second interface. The electrical circuit is disposed on the substrate. The first interface is disposed on the substrate for electrically connecting the fuel cell, and is electrically connected to the electrical circuit. The second interface is disposed on the substrate for electrically connecting an electrical device, and is electrically connected to the electrical circuit. It becomes feasible to manage the fuel cell through the electrical circuit interface board.