And most converters these day's come with a LED fitted to show its on .. I went away to work and forgot to hook up the bike to the Optimate charger, came home to find the Busa battery completely flat and shot, l found out that the permanent usb supply l had wired in for my phone was the culprit, it's now on the switch side of the circuits. I thought like some, that without a load attached there would be no current draw, i was proven wrong the hard way once again. It is a common misconception and it is never made clear in the instructions. If you get instructions with it. However there are some USB ports on EBay that have an ON/OFF switch fitted.