Originally Posted by David Larocque
I made something similar but with an SAE connector on the end that I connect to my battery tender lead - essentially its connected directly to the battery. I did measure the current draw and it is very very low, almost 0mA. IF there is something connected to the USB port then its a different story and it can drain the battery.
I was surprised by the draw. My bike sat unused for 2 weeks and that was long enough to kill the battery (nothing connected to the USB port). I suppose my battery could be weak although I haven't had any starting or other issues.