This unit, conforming to the EN54-4 European standard, can feed the panel, the field devices and the batteries, its maximum total current being of 2.5 A (load and batteries). The battery charger can control and charge two 12 V dc batteries, with a maximum capacity of 14 A/h. In case of no supply from the mains, the voltage from the batteries is automatically and with no interruption switched on to the output of the unit. The unit is provided with three open collector outputs, for remote signalling of battery charge and fault status. In normal conditions, every 30 seconds the unit checks for the efficiency of the batteries, besides performing an automatic compensation of the output voltage, depending on battery temperature.