Method for determining the capacity of a battery cell

Abstract

The invention relates to a method for determining the capacity of a battery cell. A battery cell current I is measured during a measurement period, and an open terminal voltage U,Uof the battery cell is measured at the beginning and end of the measuring period. The method has the steps of ascertaining a total battery cell current Ifrom the measured battery cell current I, ascertaining charge states SOC, SOCat the beginning and end of the measurement period using the measured open terminal voltage U,U, ascertaining an estimated value of the capacity Qusing the total battery cell current Iand a difference between the charge states SOC, SOC, ascertaining a total measurement error of the estimated value of the capacity Qfrom measurement errors of the total battery cell current Iand the charge states SOC, SOC, and ascertaining a new value of the capacity Qusing a known value of the capacity Q, the estimated value of the capacity Q, and the total measurement error. The new value of the capacity Qis in a monotonic relationship with the known value of the capacity Qand the estimated value of the capacity Qsuch that the new value of the capacity Qis determined more strongly from the estimated value of the capacity Qin the case of at least one first value of the total measurement error than in the case of at least one second value of the total measurement error, said second value lying above the at least one first value, and the new value of the capacity Qis determined less strongly from the known value of the capacity Qin the case of the first value of the value of the total measurement error than in the case of the second value of the total measurement error. The invention further relates to a computer program, a battery management system (), and a motor vehicle which are designed to carry out the method.