A battery system includes: a battery pack including a plurality of battery cells; and a battery management system for setting numbers to the battery cells by measuring cell voltages of the respective battery cells at a wake-up time, detecting a maximum cell voltage and a minimum cell voltage by periodically measuring the cell voltage of the respective battery cells after the wake-up, comparing the minimum cell voltage and the cell voltage of at least one first diagnosis target battery cell, comparing the maximum cell voltage and the cell voltage of at least one second diagnosis target battery cell, and diagnosing whether the diagnosis target battery cell is abnormal according to results of the comparison.

A measurement arrangement for determining a complex impedance of a first electrical component, wherein the measurement arrangement comprises the first component and a measuring unit, which is coupled to the first component and adapted to determine the complex impedance of the first component. The measurement arrangement comprises at least one second electrical component, which is arranged with the first component in a parallel circuit, which is hooked up in parallel with the measuring unit, wherein the parallel circuit comprises at least one switching device by which an electrical connection between the first and second component can be broken, and wherein the measurement arrangement is designed to temporarily break the electrical connection between the first component and the second component by the associated switching device in order to determine the first complex impedance of the first component.

A measurement arrangement for determining a complex impedance of a first electrical component, wherein the measurement arrangement comprises the first component and a measuring unit, which is coupled to the first component and adapted to determine the complex impedance of the first component. The measurement arrangement comprises at least one second electrical component, which is arranged with the first component in a parallel circuit, which is hooked up in parallel with the measuring unit, wherein the parallel circuit comprises at least one switching device by which an electrical connection between the first and second component can be broken, and wherein the measurement arrangement is designed to temporarily break the electrical connection between the first component and the second component by the associated switching device in order to determine the first complex impedance of the first component.

Embodiments of the present disclosure provide a server cabinet power backup system and a testing method thereof. In a self-test process of the power backup unit, the battery management module may be configured to: control the battery pack to supply power to the self-test resistor to discharge the battery pack, control the battery pack to be charged after the battery pack is discharged, and collect a charge and discharge parameter of the battery pack, and the battery management module may be further configured to: determine attenuation performance of the power backup unit according to the charge and discharge parameter of the battery pack.

A method for screening and matching cells for qualification and binning can include conducting a first and second impedance-based measurement of a cell separated by a rest interval of the cell and analyzing change/shift in the impedance spectrum obtained before and after the rest interval to afford algorithms to match, categorize, or group cells within a plurality of cells (C.sub.1 . . . C.sub.n) that have the same, substantially the same, or fall within a range of structural or functional parameters based on the impedance change/shift in the impedance spectrum.

A method for screening and matching cells for qualification and binning can include conducting a first and second impedance-based measurement of a cell separated by a rest interval of the cell and analyzing change/shift in the impedance spectrum obtained before and after the rest interval to afford algorithms to match, categorize, or group cells within a plurality of cells (C.sub.1 . . . C.sub.n) that have the same, substantially the same, or fall within a range of structural or functional parameters based on the impedance change/shift in the impedance spectrum.

The present disclosure relates to an apparatus for estimating a battery free capacity, and more particularly, an apparatus for estimating a free capacity of a half cell of a battery. According to the present disclosure, it is possible to accurately estimate a free capacity of a half cell without inserting a reference electrode by revising an entire SOC region of a half cell by using an inflection point detected based on SOC-voltage data of a full cell and a half cell of the battery, respectively, and then estimating SOC-voltage data based on a SOC difference between the entire SOC regions before and after the revision.

The present disclosure relates to an apparatus for estimating a battery free capacity, and more particularly, an apparatus for estimating a free capacity of a half cell of a battery. According to the present disclosure, it is possible to accurately estimate a free capacity of a half cell without inserting a reference electrode by revising an entire SOC region of a half cell by using an inflection point detected based on SOC-voltage data of a full cell and a half cell of the battery, respectively, and then estimating SOC-voltage data based on a SOC difference between the entire SOC regions before and after the revision.

A multi-fault diagnosis method has the following steps: measuring cell voltages of a battery pack to be diagnosed; constructing a cell voltage sequence according to measured cell voltages of the battery pack to be diagnosed, and calculating a sample entropy value of the cell voltage sequence; setting a correction coefficient for representing voltage fluctuation information, and correcting the sample entropy value through the correction coefficient to obtain a corrected sample entropy value; and judging and outputting a fault type of the battery pack to be diagnosed according to a numerical value change of the corrected sample entropy value. Faults of cells can be accurately diagnosed without a model, sample entropy values under different faults can be distinguished by setting the correction coefficient, the intuitiveness and efficiency of fault detection are improved, and the fault type and time of the lithium-ion cells can be quickly, accurately and stably diagnosed and predicted.

A multi-fault diagnosis method has the following steps: measuring cell voltages of a battery pack to be diagnosed; constructing a cell voltage sequence according to measured cell voltages of the battery pack to be diagnosed, and calculating a sample entropy value of the cell voltage sequence; setting a correction coefficient for representing voltage fluctuation information, and correcting the sample entropy value through the correction coefficient to obtain a corrected sample entropy value; and judging and outputting a fault type of the battery pack to be diagnosed according to a numerical value change of the corrected sample entropy value. Faults of cells can be accurately diagnosed without a model, sample entropy values under different faults can be distinguished by setting the correction coefficient, the intuitiveness and efficiency of fault detection are improved, and the fault type and time of the lithium-ion cells can be quickly, accurately and stably diagnosed and predicted.