Review on MICTUNING Dual USB Charger Socket Rocker Switch Style with Red LED Light - Power Outlet for Car Boat Trucks RV by John Mceachern

As with many others, polarity is EXCLUDED. If it doesn't, the charger is designed to stay lit, potentially draining or overheating the battery and potentially starting a fire. The key is the negative copper colored contact (COPPER USUALLY MEANS THE POSITIVE SIDE OF NOTHING!) and the positive contact is silver. By swapping the connections, the Lite will only turn on when the power is turned on. Just an update: low quality item will be returned. One USB plug and the switch fell apart. Don't waste money.