Abstract: A device for cutting out non-essential loads in a generator and battery-fed electric plant includes a voltage detecting unit connected across the terminals of the battery. The detecting unit may be a relay. Whenever the voltage at the terminals falls below a predetermined level, the detecting unit effects the disconnection of the non-essential load or loads from the terminals of the battery and generator, while allowing the essential load or loads. The detecting unit preferably includes a differential amplifier having one of its inputs connected to a voltage divider connected in parallel with the battery and its second input coupled to a source of reference potential.