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This is an example electrical model of a generic Li-Ion cell.

enter image description here Image credit- https://www.researchgate.net/publication/260712260_Simultaneous_Fault_Isolation_and_Estimation_of_Lithium-Ion_Batteries_via_Synthesized_Design_of_Luenberger_and_Learning_Observers

After stopping charging a cell, we expect a high voltage that slowly decays down to the OCV.

After stopping discharging a cell, we expect a low voltage that slowly decays up to the OCV.

The question is, right after stopping charging/discharging for example, can we apply a known current flow in opposite direction for a predetermined duration to rapidly bring the cell back to equilibrium & be able to measure OCV at the terminals? (instead of waiting for hours)

If this is possible, is it possible to work out the required opposite current and time reliably for a ?

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  • \$\begingroup\$ It probably depends on a lot of details. But for a lithium ion cell, I am fairly confident that you can just match coulomb-for-coulomb. As far as how rapidly the charge can be replaced, that depends on chemical reaction rate at the cell electrodes. If you try to put charge into the batter faster than it can accept, the battery may be damaged instead of recharged. \$\endgroup\$ – mkeith Sep 8 at 9:53
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The diagram you show is a simplified model of a cell. That can circuit can be brought back quickly to equilibrium as you describe.

However, a real cell is much more complicated, and has many higher order effects. If the Cp and its associated resistors are a correction to the 'zeroth order' behaviour of an ideal cell, then a real cell has many more corrections to the corrections. Unfortunately, they tend to be temperature sensitive, and long-term history dependent, so can't really be used for accurate prediction of useful things like state of charge in the middle ranges of SOC.

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