MONNIT's MNS2-9-IN-VD-200 ALTA voltage detector 50 VDC detects the presence or absence of electricity. It is intended for use on battery or other DC sources, up to 50 V. Not intended for use with AC Voltages. It is perfect for batteries, adapters, solar equipment, vehicles or machinery, and any other electrical appliance monitoring. The sensor triggers on voltage presence to voltage absence and vice versa. The data is displayed as "voltage detected" or "no voltage".