Abstract: 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.

Abstract: A device for a battery charger, includes connection elements 14, 16 connected to the output lines of the charger, connection elements 16, 24 for connection to the terminals of a battery to be charged. The device includes elements 80 for detecting a voltage over the output lines of the charger, elements 80 for detecting a positive voltage over the terminals of a connected battery, switch elements 60 for connecting at least one of the output lines to the connection elements to the terminals of the battery, and a switch activating element 70 arranged to the voltage detection elements and designed and arranged such that it is capable of activating the switch when a voltage is detected over the output lines of the charger and a positive voltage is detected over the terminals of the connected battery, thereby connecting the charger to the battery.