I bought one of these a few months ago and it didn't work. Since I connected it to a camper converter I figured I might have reversed the polarity. I swapped out the cords, heard a bang in the outlet and handed it in for a refund. I accidentally bought another one and decided to connect it to an existing 12 volt light bulb to avoid wiring errors. I connected the cables as instructed by the manufacturer and again the USB ports didn't work. I have power for the light and the cords I routed to the outlet but nothing comes out of the outlet. I figured what the heck, I'll swap the wires again like I did last time, and again I heard a pop in the outlet. Don't waste your money on this product.