The invention relates to a device (1) having at least one fuel cell (2) and a DC/DC converter (3) assigned to the latter. A variable voltage generated in the fuel cell (2) is converted, by means of the DC/DC converter (3), into a DC voltage for a system (4) to be supplied. The DC/DC converter (3) is designed to capture internal characteristic variables of the fuel cell (2). Operating states of the fuel cell (2) are captured and/or controlled in dependence on these characteristic variables.

The invention relates to a device (1) having at least one fuel cell (2) and a DC/DC converter (3) assigned to the latter. A variable voltage generated in the fuel cell (2) is converted, by means of the DC/DC converter (3), into a DC voltage for a system (4) to be supplied. The DC/DC converter (3) is designed to capture internal characteristic variables of the fuel cell (2). Operating states of the fuel cell (2) are captured and/or controlled in dependence on these characteristic variables.

Provided herein are methods for operating carbon oxide (CO.sub.x) reduction reactors (CRR) and related apparatus. In some embodiments, the methods involve shutting off, reducing, or otherwise controlling current during various operation stages including hydration, break-in, normal operation, planned shut-offs, and extended shutoff or storage periods.

A fuel cell system includes a fuel cell a temperature acquisition unit that acquires a temperature of the fuel cell, a cell unit voltage sensor that detects a voltage of each of fuel cell units, and a controller that controls the fuel cell system. The controller restricts an output current of the fuel cell when the voltage of the individual fuel cell unit becomes equal to or lower than a predetermined value in a warm-up operation, execute the warm-up operation when the temperature of the fuel cell is equal to or lower than a predetermined temperature, after the fuel cell system receives a start-up request, and stop an operation of the fuel cell system when a stop condition including that the voltage of the fuel cell unit is continuously equal to or lower than a predetermined voltage value for a predetermined time is satisfied after start of the warm-up operation.

An electrical power supply system has a fuel cell module and a battery. The fuel cell can be selectively connected to the battery system through a diode. The system preferably also has a current sensor and a controller adapted to close a contactor in a by-pass circuit around the diode after sensing a current flowing from the fuel cell through the diode. The system may also have a resistor and a contactor in another by-pass circuit around the diode. In a start-up method, a first contactor is closed to connect the fuel cell in parallel with the battery through the diode and one or more reactant pumps for the fuel cell are turned on. A current sensor is monitored for a signal indicating current flow through the diode. After a current is indicated, a by-pass circuit is provided around the diode.

System and method for fuel-cell and motor trend monitoring including recording signals from fuel-cell and motor system-condition sensors or sets of onboard sensors and periodically analyzing results to examine fuel-cell and motor system performance trends to predict the need for fuel-cell or motor system maintenance. Various analyses can be performed, separately or in parallel, including: comparing the current parameter values with recorded parameter values in previous instances of similar operating conditions; comparing parameter values to predetermined nominal ranges; and detecting sensed parameter values that exceed recommended fuel-cell or motor system operating conditions or that exhibit trends over time that if continued result in exceeding fuel-cell or motor system operating conditions or producing out-of-bound readings. Results of the analyses inform fuel-cell, motor, and aircraft system maintenance scheduling and provide alerts to users regarding recommended fuel-cell, motor, and aircraft system performance trends and/or operating condition exceedances, enhancing safety and improving maintenance efficiency.

Systems and methods for operating an electric energy storage device are described. The systems and methods may reduce a voltage potential between a ground reference and terminals of an electric energy storage device. By lowering the voltage potential, a possibility of unintentionally discharging the electrical energy storage device to ground may be reduced.

A fuel cell power generation system includes: a first fuel cell; and a second fuel cell connected to a downstream side of the first fuel cell via an exhaust fuel gas line, the second fuel cell being capable of generating electric power using an exhaust fuel gas from the first fuel cell. A water recovery unit is disposed on the exhaust fuel gas line, the water recovery unit being capable of recovering water contained in the exhaust fuel gas. A bypass line brings an upstream side and a downstream side of the exhaust fuel gas line with respect to the water recovery unit into communication. At least one flow control valve is disposed on at least one of the exhaust fuel gas line or the bypass line. A control unit controls an opening degree of the at least one flow control valve.

An electric power supply device supplies electric power to a work machine having an electric power source. The electric power supply device includes a fuel cell different from the electric power source and an electric power connecting section for transferring electric power between the electric power source and the electric power supply device. A control device for controlling the electric power supply device includes a rated capability obtaining section for obtaining the information indicating the rated value of the charge and discharge capability of the electric power source of the work machine in response to the electric power supply device being mounted in the work machine or the electric power supply device being able to utilize the electric power of the electric power source, and an operating condition determining section for determining the operating condition of the electric power supply device based on the rated value.

A voltage applying unit of a water detecting device applies, to a pair of electrodes, a voltage changing within an application range that includes a first voltage which is smaller than an electrolysis voltage of water and a second voltage which is larger than the electrolysis voltage of the water. A judging unit judges presence or absence of the water based on change in electric current measured by a current measuring unit when the voltage changing within the application range is applied to the pair of electrodes.