Abstract: A method for determining the parameters of an equivalent circuit for representation of the impedance of a lithium ion cell is provided. The equivalent circuit includes at least one RC element having an ohmic resistor R1, a capacitor C1, and a series resistor Rs. The series resistor Rs is determined by an impedance measurement.

Abstract: A method monitors the functional capability of the cooling system of an operating high-voltage accumulator for an electric drive unit of a motor vehicle. The method repeatedly measures the temperature of the high-voltage accumulator by use of a temperature sensor mounted on the high-voltage accumulator; checks whether the measured temperature value is above a cooling threshold temperature; determines a profile of the temperature of the high-voltage accumulator using a temporal sequence of the measured temperature values of the high-voltage accumulator which are above the cooling threshold temperature; and diagnoses that the cooling system is operating correctly if the temperature profile does not exceed a predetermined threshold.

Abstract: A method for operating a battery having at least two battery cells includes a symmetrization process, in which states of charge of the battery cells are symmetrized continuously or repeatedly; a first measurement process that runs across a first predefined duration during symmetrization and in which measurements are performed repeatedly. In each of the measurements, the battery cell that has the lowest quiescent voltage out of the battery cells in the measurement is determined. It is determined whether the same battery cell was always determined as the battery cell having the lowest quiescent voltage during the first measurement process; and when this is the case a checking process is performed in which symmetrization is interrupted or terminated and it is checked whether the battery cell for which the lowest quiescent voltage was always determined during the first preceding measurement process exhibits increased charge loss that indicates a possible defect.

Abstract: A method monitors the functional capability of the cooling system of an operating high-voltage accumulator for an electric drive unit of a motor vehicle. The method repeatedly measures the temperature of the high-voltage accumulator by use of a temperature sensor mounted on the high-voltage accumulator; checks whether the measured temperature value is above a cooling threshold temperature; determines a profile of the temperature of the high-voltage accumulator using a temporal sequence of the measured temperature values of the high-voltage accumulator which are above the cooling threshold temperature; and diagnoses that the cooling system is operating correctly if the temperature profile does not exceed a predetermined threshold.