Circuit arrangement for charging rechargeable batteries

A circuit arrangement for charging batteries comprises a charging current source for supplying charging current pulse trains. The circuit arrangement comprises a first detection device for determining an actual voltage dependent upon a variable reference voltage, which actual voltage is proportional to the average sum voltage of a battery. The first detection device supplies a detection signal corresponding to the detection result and which controls the duty cycle of the pulse-shaped control signal which can be generated by a control pulse generator. The control pulse generator varies the duty cycle dependent on the detection signal when the actual voltage increases or the reference voltage decreases, in a manner such that the ratio between the charging period and the charging pause in a charging pulse train is reduced. A device is provided which enable the reference voltage to be varied in the same sense as the duty cycle depending on this duty cycle.