Part of Cell open-circuit voltage, ‣, and Cell parameters.
The OCV function is one of the Cell parameters that can (and should) be estimated at once, e. g. by a stochastic estimator proposed in this paper. We should then use these parameters to calculate SoH, remaining battery life predictions, and in the SoC estimation algorithm.
However, from the efficiency point of view, if we assume that the OCV function changes for all batteries similarly (depending on the particular temperature/SoC cycling history) with the change in the remaining capacity, we don’t lose much fleet-wide.
We can use the remaining capacity as a proxy to the OCV function in cell parameter estimation. Currently, 95% of SoC algorithms in production even use completely static OCV function, independent of the remaining capacity, which is a much bigger simplification leading to bigger SoC estimation errors in batteries that are already sufficiently degraded. Yet, they are fine with this.
Note there is a small chicken-and-egg problem here: we cannot actually estimate the remaining capacity without knowing the current OCV function of a battery. But a simple iteration when the previous iteration’s OCV is used to estimate new remaining capacity, which is used to determine the “new” OCV should be fine. (TODO: check if errors cannot snowball here?)
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