A device for reducing the output current of a primary switched battery charger, which charger includes an input DC power circuit, a high frequency transformer and control unit for modulating the DC input power. The device includes elements for measuring pulse ratio of switch pulses on the output side of the charger, elements for measuring peak value of output voltage, elements for differentially amplifying the signals measured and elements for integrating voltage/current of the differentially amplified signals, wherein the integrated voltage/current is used for modulating the input DC power in order to reduce the output current. The device includes elements for measuring the output effect of the charger, elements for measuring the output voltage of the charger, elements for dividing the signals measured and elements for multiplexing voltage/current of the output from the elements for dividing, wherein the multiplexed voltage/current is used for modulating the input DC power in order to reduce the output current.