Battery state-of-health determination using multi-factor normalization
First Claim
1. A method for determining a state of health (SoH) of a battery, comprising:
- connecting the battery to a tester comprising a user interface, a voltage sensor, a load and a processor;
receiving, in the tester via the user interface, a nominal or maximum cut-off voltage of the battery;
receiving, in the tester via the user interface, a capacity of the battery;
measuring, by the voltage sensor of the tester, an initial OCV (open circuit voltage) V1 of the battery;
drawing, by the load, a pulse of current from the battery to the tester, said pulse having an amplitude that is normalized to the capacity;
measuring, by the processor, a voltage response of the battery to the pulse;
selecting, from a plurality of OCV regions, by the processor, an OCV region that V1 lies in, wherein each OCV region has an associated, different set of thresholds, and each OCV region corresponds to a different initial state of charge range for the battery;
adjusting, by the processor, the voltage response using the nominal or maximum cut-off voltage and using the selected OCV region;
comparing, by the processor, said adjusted response to at least one of the thresholds associated with the selected OCV region; and
determining, by the processor using said comparison, whether the SoH is above or below a predefined cut-off value.
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Accused Products
Abstract
A battery is subjected to a discharge current pulse that is normalized to its capacity. The battery voltage is measured before, during and after the pulse, and various parameters are calculated therefrom. The parameters are adjusted depending on both the value of the nominal or maximum cut-off voltage of the battery and on its open circuit voltage prior to the pulse. Based on the open circuit voltage, one of multiple different analysis paths is selected, each representing a different state of charge range. The analysis selected involves a comparison of the adjusted parameters with a set of thresholds that are specific to the selected analysis and that depend on the desired cut-off point between good and poor state of health. Batteries of different nominal voltages, capacities and chemistries can be tested without knowing their state of charge and without the tester having been calibrated for a specific battery model.
20 Citations
20 Claims
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1. A method for determining a state of health (SoH) of a battery, comprising:
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connecting the battery to a tester comprising a user interface, a voltage sensor, a load and a processor; receiving, in the tester via the user interface, a nominal or maximum cut-off voltage of the battery; receiving, in the tester via the user interface, a capacity of the battery; measuring, by the voltage sensor of the tester, an initial OCV (open circuit voltage) V1 of the battery; drawing, by the load, a pulse of current from the battery to the tester, said pulse having an amplitude that is normalized to the capacity; measuring, by the processor, a voltage response of the battery to the pulse; selecting, from a plurality of OCV regions, by the processor, an OCV region that V1 lies in, wherein each OCV region has an associated, different set of thresholds, and each OCV region corresponds to a different initial state of charge range for the battery; adjusting, by the processor, the voltage response using the nominal or maximum cut-off voltage and using the selected OCV region; comparing, by the processor, said adjusted response to at least one of the thresholds associated with the selected OCV region; and determining, by the processor using said comparison, whether the SoH is above or below a predefined cut-off value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A device for determining state of health (SoH) of a battery, comprising:
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a connection to a battery to be tested; a user interface configured to receive a nominal or maximum cut-off voltage of the battery and a capacity of the battery; a voltage sensor to detect an initial OCV (open circuit voltage) V1 of the battery; a load configured to draw a pulse of current from the battery, said pulse having an amplitude that is normalized to the capacity; and a processor configured to; obtain a voltage response of the battery to the pulse; select, from a plurality of OCV regions, an OCV region that V1 lies in, wherein each OCV region has an associated, different set of thresholds, and each OCV region corresponds to a different initial state of charge range for the battery; adjust the voltage response using the nominal or maximum cut-off voltage and using the selected OCV region; compare said adjusted response to at least one of the thresholds associated with the selected OCV region; and determine, using said comparison, whether the SoH is above or below a predefined cut-off value. - View Dependent Claims (19, 20)
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Specification