METHOD FOR DETERMINING THE STATE OF CHARGE OF A BATTERY

摘要

The invention relates to a method for determining the state of charge of a battery, wherein a functional relationship between the state of charge and the open-circuit voltage of the battery is empirically determined. In the determination of the functional relationship, the battery, which is completely charged at the beginning, is discharged with defined charges and open-circuit voltages are measured at several discharge steps of the battery, wherein states of charge of the battery are associated with the measured open-circuit voltages after the measurements. After the determination of the functional relationship, during operation of the battery, the state of charge is determined from an estimated open-circuit voltage on the basis of the functional relationship. In a first phase in the determination of the functional relationship between the state of charge and the open-circuit voltage, the battery is discharged in steps at constant amperages until the open-circuit voltage falls below a limit voltage, and then in a second phase the amperage is reduced in a further step and the battery is discharged further until the amperage falls below a limit amperage. The invention further relates to a device for performing such a method, wherein the device comprises at least one battery, a controller for controlling the input and output power in an open-loop or closed-loop manner, a computing unit for determining the state of charge of the battery, and a data memory, wherein the data of the functional relationship between the state of charge and the open-circuit voltage are stored in the data memory and the computing unit has access to the data memory.