Patent ID: 8823326

Claim:
A method for determining the state of charge of a battery during a charging or discharging phase of the battery, wherein the method comprises the following successive steps during said phase: measuring the current I flowing through the battery before the battery is placed in open circuit, placing the battery in open circuit during a rest period, measuring at least first and second values of the voltage at the terminals of the battery at different times during the rest period, determining an indicator ind 2 based on the current I and the voltage values measured during the rest period, the indicator ind 2 being given by the formula ind ⁢ ⁢ 2 = U ( t ⁢ ⁢ 2 ) - α U ( t ⁢ ⁢ 2 ) - U ( t ⁢ ⁢ 1 ) × I where U (t1) is the first voltage value measured during the rest period, U (t2) is the second voltage value measured during the rest period, and α is a parameter determined beforehand during a calibration phase by successive iterations of α, to obtain a monotone calibration curve, and determining the state of charge corresponding to the indicator ind 2 by means of a calibration curve representative of the variations of the indicator ind 2 as a function of the state of charge during the charging or discharging phase.