I hooked up a 12 volt relay to my Livewire. The power to trip the coil comes from the bottom blue wire on the head light. The supply 12 volt wire comes from the blue wire that has two loops that comes from the 40amp main fuse. For the 12 volt supply wire I use a battery tender with a 20 amp fuse. I power a pair of Harley electric grips and my electric jacket, pants, gloves.