Abstract: A method for determining at least one estimated operating parameter of a battery including receiving at least one measured operating parameter of the battery and determining the at least one estimated operating parameter from the at least one measured operating parameter using a mathematical battery model based on an equivalent circuit of the battery having at least one RC element. The battery model defines a relationship between the battery voltage applied to the battery and a battery current flowing through the battery in dependence of model parameters including at least one time constant and/or at least one electrical resistance with respect to the equivalent circuit. The battery model takes into account an n-th power of a Taylor series expansion of the at least one time constant and/or the at least one electrical resistance around an operating point of the battery.

Abstract: An electronic circuit for determining a charging state of a battery cell of a battery system. The electronic circuit is configured for obtaining a plurality of measured values of an open-circuit voltage of the battery cell with corresponding time values for which the measured values of the open-circuit voltage have been measured. The electronic circuit is further configured for determining a time up until which a charging state corresponding to an end point voltage of the battery cell is reached on the basis of an analytical solution of a function, which specifies a connection between the open-circuit voltage and the charging state of the battery cell. The electronic circuit is further configured for determining the charging state of the battery cell based on a reverse function of the charging-state dependent time.