The 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 volts. 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".