METHOD FOR ESTABLISHING LITHIUM SECONDARY BATTERY CHARGING PROTOCOL, BATTERY MANAGEMENT SYSTEM, BATTERY PACK, AND BATTERY CELL CHARGING DEVICE

Systems and methods for charging protocols for secondary batteries are provided including: measuring an open-circuit voltage (V) according to a state-of-charge (SOC) for a two-electrode cell, charged with a reference current; measuring second open-circuit voltages (V) according to the state-of-charge when charging the cell with a plurality of different charging currents; calculating an internal resistance value (R) according to the state-of-charge using an equation (R)=(V−V)/Ic for the different charging currents, wherein Ic is a value for the different charging currents, and computing a charging current-specific internal resistance profile mapping the internal resistance value according to the state-of-charge for the different charging currents; and identifying, for the charging current-specific internal resistance profiles, each inflection point, determining a lowest resistance value among the inflection points as a reference value, and determining, for the computed charging current-specific internal resistance profiles, the state-of-charge having the reference value as a limit state-of-charge.