A power supply device for the electric power supply of at least one consumer is provided having a primary power grid in which there is present a fuel cell arrangement comprising electric contacts which includes a discharge circuit switched in parallel and connected to the electric contacts comprising a switch element activatable by means of a controller across a switch line as well as a resistance element and having a DC-DC converter which is present in the primary power grid by which the primary power grid is connected to a secondary power grid characterized in that the discharge circuit comprises a safety device or a safety function, which holds the switch element in an opened state and thereby makes the discharge circuit inactive for as long as an actuating possibility exists via the switch line, and which places the switch element in a closed state and thereby makes the discharge circuit active for lowering the voltage of the fuel cell arrangement once the actuating possibility via the switch line is denied. Furthermore, a method for lowering the voltage of a fuel cell arrangement of a power supply device is also provided.

The present invention is directed to a redox flow battery comprising at least one electrochemical cell in fluid communication with a balancing cell, said balancing cell comprising: a first and second half-cell chamber, wherein the first half-cell chamber comprises a first electrode in contact with a first aqueous electrolyte of the redox flow battery; and wherein the second half-cell chamber comprises a second electrode comprising a catalyst for the generation of O.sub.2; and wherein the second half-cell chamber does not contain an aqueous electrolyte.

A control system is intended to be tailored to a fuel-cell stack. This fuel-cell stack includes a plurality of cells connected in series between a first terminal and a second terminal. This system includes a central control unit and an electronic bypass device including a plurality of separate electrical bypass units, each electrical bypass unit being connected in parallel to at least one separate cell of the fuel-cell stack, in order to control its discharge on startup and shutdown of the stack and thus to avoid the creation of inverse electrical potentials and to limit the presence of residual potentials.

The present invention is directed to a redox flow battery comprising at least one electrochemical cell in fluid communication with a balancing cell, said balancing cell comprising: a first and second half-cell chamber, wherein the first half-cell chamber comprises a first electrode in contact with a first aqueous electrolyte of the redox flow battery; and wherein the second half-cell chamber comprises a second electrode comprising a catalyst for the generation of O.sub.2; and wherein the second half-cell chamber does not contain an aqueous electrolyte.

A fuel cell module is configured or operated, or both, such that after a shut down procedure a fuel cell stack is discharged and has its cathode electrodes at least partially blanketed with nitrogen during at least some periods of time. If the fuel cell module is restarted in this condition, electrochemical reactions are limited and do not quickly re-charge the fuel cell stack. To decrease start up time, air is moved into the cathode electrodes before the stack is re-charged. The air may be provided by a pump, fan or blower driven by a battery or by the flow or pressure of stored hydrogen. For example, an additional fan or an operating blower may be driven by a battery until the fuel cell stack is able to supply sufficient current to drive the operating blower for normal operation.

The present invention comprises a method and system for improving the energy efficiency of a vanadium flow battery, VFB. This is achieved by simultaneously reconditioning the VFB through in-situ activation of the electrodes.

A fuel cell purging method is provided to effectively prevent fuel cell deterioration and degradation of durability of the fuel cell by performing hydrogen purging at a point in time at which negative pressure of an anode peaks after a fuel cell vehicle is stopped. The fuel cell purging method includes stopping the driving of a fuel cell vehicle and continuously measuring pressure of an anode of a fuel cell after the fuel cell vehicle is stopped. Additionally, hydrogen is supplied to the anode when the measured pressure of the anode reaches a negative pressure peak time point.

A power supply device for the electric power supply of at least one consumer is provided having a primary power grid, in which there is present a fuel cell arrangement comprising electric contacts, which includes a discharge circuit switched in parallel and connected to the electric contacts, comprising a switch element activatable by means of a controller across a switch line as well as a resistance element, and having a DC-DC converter which is present in the primary power grid, by which the primary power grid is connected to a secondary power grid, characterized in that the discharge circuit comprises a safety device or a safety function, which holds the switch element in an opened state and thereby makes the discharge circuit inactive for as long as an actuating possibility exists via the switch line, and which places the switch element in a closed state and thereby makes the discharge circuit active for lowering the voltage of the fuel cell arrangement once the actuating possibility via the switch line is denied. Furthermore, a method for lowering the voltage of a fuel cell arrangement of a power supply device is also provided.

A fuel cell system includes: a fuel cell; a voltage regulator that regulates an output voltage of the fuel cell; and a controller configured to perform a refresh process of decreasing the output voltage of the fuel cell to a reduction voltage at which an oxide film formed on the cathode is reduced, by controlling the voltage regulator. The controller, before the refresh process, calculates a first amount, the first amount being an amount by which the oxide film is to be removed from the cathode. The controller determines, as the output voltage of the fuel cell, a refresh voltage that enables the first amount of the oxide film to be removed within a preset reference time. The controller operates the voltage regulator so as to cause the output voltage of the fuel cell to become the refresh voltage when the refresh process is performed.

The present invention is directed to a redox flow battery comprising at least one electrochemical cell in fluid communication with a balancing cell, said balancing cell comprising: a first and second half-cell chamber, wherein the first half-cell chamber comprises a first electrode in contact with a first aqueous electrolyte of the redox flow battery; and wherein the second half-cell chamber comprises a second electrode comprising a catalyst for the generation of O.sub.2; and wherein the second half-cell chamber does not contain an aqueous electrolyte.