According to u/Krexington\_III answer [from Reddit](https://www.reddit.com/r/explainlikeimfive/comments/1qrdc9/eli5how_do_digital_devices_know_how_much_energy/cdfvviy/?utm_source=share&utm_medium=web2x&context=3), to estimate battery state of charge in a mobile device, such as a cell phone, and do it pretty accurately (and without a need of heavy stuff like a neural network) device needs to use 2 methods - coulomb counter (integral of current over the time to get the amount of charge which left/went into the battery) and open-circuit voltage method (mapping voltage of relaxed battery [when a cell phone is sleeping] to the state of charge). The second one is used to calibrate coulomb counter drift due to constant error and find what the SoC is at the beginning.

Does anyone know how to implement coulomb counter calibration using the open-circuit voltage method? Is mixing both values using some function or some type of average enough, or is it just overriding coulomb counter estimation with a voltage-based one?