Abstract: A method for controlling the quality of the coolant for fuel cell systems, it being proposed to measure and monitor the insulation resistance of the load circuit of the fuel cell system. It has become apparent that there is a functional, uniquely defined relationship between the measured insulation resistance and the electrical conductivity of the coolant so that a separate measurement of the electrical conductivity by means of corresponding sensor systems and evaluation means can be dispensed with in the present invention.

Abstract: The invention relates to a vehicle with a fuel cell for producing power. The vehicle has a monitoring and switching unit which is enclosed in a housing that is detachably connected to the fuel cell housing.

Abstract: A method for controlling the quality of the coolant for fuel cell systems, it being proposed to measure and monitor the insulation resistance of the load circuit of the fuel cell system. It has become apparent that there is a functional, uniquely defined relationship between the measured insulation resistance and the electrical conductivity of the coolant so that a separate measurement of the electrical conductivity by means of corresponding sensor systems and evaluation means can be dispensed with in the present invention.

Abstract: A method for controlling the quality of the coolant for fuel cell systems, it being proposed to measure and monitor the insulation resistance of the load circuit of the fuel cell system. It has become apparent that there is a functional, uniquely defined relationship between the measured insulation resistance and the electrical conductivity of the coolant so that a separate measurement of the electrical conductivity by means of corresponding sensor systems and evaluation means can be dispensed with in the present invention.

Abstract: The invention relates to a vehicle (1) with a fuel cell (2) for producing power. The vehicle has a monitoring and switching unit (18) which is detachably attached to the fuel cell housing, in a housing (19).

Abstract: A fuel cell system comprises a plurality of fuel cells arranged in a stack between two end plates. An electrical load is connected to the fuel cell stack via a load circuit, and a diode is arranged between the fuel cell stack and the electrical load in the load circuit. According to the invention, the diode is arranged directly on or in one of the end plates. Moreover, a cooling device, which is in thermal contact with the diode and dissipates the power loss from the diode, is provided in the region of the diode.

Abstract: An apparatus for measuring the voltage of a plurality of voltage sources mounted in a stack includes a plurality of contact units, each having a plurality of electrical contacts mounted therein, for voltage tapping of the voltage sources. The contact units are held in a support module, arranged side by side along a longitudinal axis. An evaluation unit is coupled in communication with the contacts contained in the contact units, either directly, or via an intermediate unit that includes addressing and processing capability. The number of contact units that are arranged in the support module is variable in accordance with the number of voltage sources contained in the stack, and the contact units themselves are movable longitudinally within the support module to accommodate spacing of the voltage sources in the stack.

Abstract: A method for controlling the quality of the coolant for fuel cell systems, it being proposed to measure and monitor the insulation resistance of the load circuit of the fuel cell system. It has become apparent that there is a functional, uniquely defined relationship between the measured insulation resistance and the electrical conductivity of the coolant so that a separate measurement of the electrical conductivity by means of corresponding sensor systems and evaluation means can be dispensed with in the present invention.

Abstract: A fuel cell system comprises a plurality of fuel cells arranged in a stack between two end plates. An electrical load is connected to the fuel cell stack via a load circuit, and a diode is arranged between the fuel cell stack and the electrical load in the load circuit. According to the invention, the diode is arranged directly on or in one of the end plates. Moreover, a cooling device, which is in thermal contact with the diode and dissipates the power loss from the diode, is provided in the region of the diode.