A semiconductor device that is of a face-down mounted chip-size package type, discharges electric charges stored in an electric storage device (battery), and has a power loss area ratio of at least 0.4 (W/mm.sup.2) obtained by dividing a power loss (W) in the semiconductor device at time of the discharge by an area (mm.sup.2) of the semiconductor device, the semiconductor device comprising: a field-effect transistor of a horizontal type and a resistor that are connected in series in stated order between an inflow terminal and an outflow terminal; and a control circuit that causes a discharge current to be constant without depending on an applied voltage between the inflow terminal and the outflow terminal. A difference between a maximum temperature of a field-effect transistor portion and a temperature of a resistor portion is within five degrees Celsius in a discharge period.

A semiconductor device that is of a face-down mounted chip-size package type, discharges electric charges stored in an electric storage device (battery), and has a power loss area ratio of at least 0.4 (W/mm.sup.2) obtained by dividing a power loss (W) in the semiconductor device at time of the discharge by an area (mm.sup.2) of the semiconductor device, the semiconductor device comprising: a field-effect transistor of a horizontal type and a resistor that are connected in series in stated order between an inflow terminal and an outflow terminal; and a control circuit that causes a discharge current to be constant without depending on an applied voltage between the inflow terminal and the outflow terminal. A difference between a maximum temperature of a field-effect transistor portion and a temperature of a resistor portion is within five degrees Celsius in a discharge period.

The present invention provides a method for detecting a ground fault in a battery of a uninterrupted power supply, the battery includes at least one string with multiple battery cells, the method including the steps of defining multiple individual battery blocks of battery cells along the at least one string, performing an reference impedance measurement for the multiple individual battery blocks at a first point of time, performing a verification impedance measurement for the multiple individual battery blocks at a second point of time, evaluating a change of measured impedance between the reference impedance and the verification impedance for the multiple individual battery blocks of the at least one string, and identifying a ground fault based on a correlated change of measured impedance of the multiple individual battery blocks along the at least one string. The present invention also provides a battery management system for managing a battery of a uninterrupted power supply, which is adapted to perform the above method. The present invention further provides a UPS device and a UPS system, each of which including an above battery management system.

The present invention provides a method for detecting a ground fault in a battery of a uninterrupted power supply, the battery includes at least one string with multiple battery cells, the method including the steps of defining multiple individual battery blocks of battery cells along the at least one string, performing an reference impedance measurement for the multiple individual battery blocks at a first point of time, performing a verification impedance measurement for the multiple individual battery blocks at a second point of time, evaluating a change of measured impedance between the reference impedance and the verification impedance for the multiple individual battery blocks of the at least one string, and identifying a ground fault based on a correlated change of measured impedance of the multiple individual battery blocks along the at least one string. The present invention also provides a battery management system for managing a battery of a uninterrupted power supply, which is adapted to perform the above method. The present invention further provides a UPS device and a UPS system, each of which including an above battery management system.

A method for recognizing contacting errors in a rechargeable battery pack. Each rechargeable battery of the rechargeable battery pack is connected in parallel to at least one further rechargeable battery of the rechargeable battery pack. The method includes: applying at least one current to the rechargeable battery pack; ascertaining at least one voltage that is present at the rechargeable battery pack, as a function of the applied current; determining at least one parameter based on the ascertained voltage; and comparing the parameter to a comparison variable.

A method for recognizing contacting errors in a rechargeable battery pack. Each rechargeable battery of the rechargeable battery pack is connected in parallel to at least one further rechargeable battery of the rechargeable battery pack. The method includes: applying at least one current to the rechargeable battery pack; ascertaining at least one voltage that is present at the rechargeable battery pack, as a function of the applied current; determining at least one parameter based on the ascertained voltage; and comparing the parameter to a comparison variable.

Disclosed is a method and apparatus for testing an internal short of a secondary battery by simulating the use environment situation where the secondary battery is actually used, and a secondary battery for an internal short test, which is used in the method. The method for testing an internal short of a secondary battery includes the steps of mounting a P-N junction diode in a secondary battery; charging the secondary battery; and evaluating a state of the secondary battery by considering that an internal short occurs in the secondary battery when the P-N junction diode is switched on.

Provided are a cell screening device for selecting battery cells of a high-risk group, and a cell screening method using the same. According to the present invention, the battery cells may be ordered in the order of high probability of being out of an upper limit value or a lower limit value of an operating voltage among a plurality of battery cells using state information calculated for each battery cell, thereby making it possible to select the battery cells of the high-risk group.

Provided are a cell screening device for selecting battery cells of a high-risk group, and a cell screening method using the same. According to the present invention, the battery cells may be ordered in the order of high probability of being out of an upper limit value or a lower limit value of an operating voltage among a plurality of battery cells using state information calculated for each battery cell, thereby making it possible to select the battery cells of the high-risk group.

A method for non-invasive characterisation of a cell for a battery is provided, the method comprising: measuring a magnetic field generated by the cell using a plurality of magnetic field sensors positioned adjacent to the cell, the measuring producing magnetic field sensor data, wherein the measuring is performed while the cell is in a passive state; determining current density profile data across the cell based on the magnetic field sensor data; and determining a condition of the cell using the current density profile data.