| CPC G01R 31/389 (2019.01) [G01R 27/02 (2013.01); G01R 31/367 (2019.01); G01R 31/396 (2019.01)] | 12 Claims |
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1. A method comprising:
determining, by a measurement arrangement comprising an impedance measurement assembly, a respective impedance curve for a plurality of cells extracted from a plurality of rechargeable batteries, wherein the impedance measurement assembly comprises a controller and an adjustable load, wherein each impedance curve is descriptive of an internal impedance of the respective cell as a function of frequency over a predefined frequency range, derived via the following procedure:
setting, by the controller, an impedance of the adjustable load coupled between terminals of the respective cell between two or more predefined values according to a multi-frequency pseudo-random pulse sequence (PRPS) that represents a plurality of frequency components at a predefined frequency resolution within the predefined frequency range and that defines switching between said two or more predefined values as a function of time, and
deriving, by the controller, the internal impedance of the respective cell over the predefined frequency range based on a voltage across the terminals of the respective cell and an electric current supplied to the adjustable load as a function of time;
determining, by the impedance measurement assembly, for each of the plurality of cells, respective one or more impedance characteristics based on the impedance curve determined for the respective cell, wherein said one or more impedance characteristics for a given cell comprise an indication of the number of partially circular segments appearing in a complex-plane representation of the impedance curve determined for the respective cell and respective frequency sub-ranges within which said partially circular segments appear;
sorting, by the controller or a computing apparatus operably coupled to the measurement arrangement, the plurality of cells into one of a first quality class or a second quality class in accordance with the one or more impedance characteristics determined for the plurality of cells; and
selecting, by the controller or the computing apparatus operably coupled to the measurement arrangement, a set of the plurality of cells sorted into the first quality class for one or more batteries,
wherein said sorting comprises at least one of the following:
applying one or more qualification criteria, comprising assigning a cell into a first cell quality class in response to the one or more impedance characteristics derived for the respective cell meeting the one or more qualification criteria and assigning the cell into the second cell quality class in response to said one or more impedance characteristics failing to meet the one or more qualification criteria;
applying one or more disqualification criteria, comprising assigning a cell into the first cell quality class in response to the one or more impedance characteristics derived for the respective cell failing to meet the one or more disqualification criteria and assigning the cell into the second cell quality class in response to said one or more impedance characteristics meeting the one or more disqualification criteria.
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