Originally Posted by macadamia
The best way I found is to purchase a "automotive relay" from radio shack and use a Centech AP-1 or similar wiring block for the bike. Use the diagram below...
Nice information MacNut! (and don't ever change your avatar please!
I have several jury rigged electrical add-ons including one I just added for my Garmin Montana.
Before I got the Montana, I already had a cigarette adapter socket under my seat that has a Powerlet plug on the other end that just dangles next to the Powerlet outlet on the side when I'm not using it. The Powerlet outlet is always HOT so I figured this setup would be perfect for charging my USB devices at night when on trips. In that case I always have a tank bag on so I run the USB cable into the tank bag and just leave it there and the other end is always plugged into a USB to cigarette adapter that is plugged into the cigarette socket under my seat. Then if I want to charge a USB device I plug in the cable dangling by the Powerlet socket. At night for a couple of hours I don't want to turn my key (and headlights) on just to charge a low current device for a short while, though I try to charge it while I ride and rely on Bluetooth if possible.
The point is I figured for the Montana I would just tap into this same circuit which is unswitched, which means it stays powered on when I turn the key off. I'm starting to think this will bite me someday and I'll forget to unplug the powerlet and leave the Garmin attached, so I'm thinking I need to pick it off of a different place that is key switched. p.s. I think somebody measured the Garmin and when off it only takes a few mA of current (was it 8mA or ?) so it's not a huge deal as long as you turn it off.
The Montana rugged mount has a long battery lead with an inline fuse, a ground, and an audio jack output (for turn by turn directions). It also has 2 more data wires you can simply seal as you probably won't use them. In my case I want to move the rugged mount to another vehicle so I wanted a connector in the power lines to I could quickly disconnect and remove it. So below the Y in the cable where the wires become separated, I cut off only the 2 power lines and installed a waterproof 2-pin automotive connector (Delphi Weatherpak). Tip: use Liquid Electrical Tape from Gardner Bender (at Ace hardware) to fully seal the wires at connectors yet it remains flexible since it is rubbery. This stuff is awesome! The connector is kinda bulky though but I coiled up the excess wire and stashed it all under the handlebars in the center.
I also have AdvMonster.com aux LED lights (< 2 A) that I wired into a SWITCHED circuit at the fuse box by using a Posi-Tap at a wire coming into a fuse. If you want to be quick you could also pick off of an existing fuse but you must carefully decide which fuse to pick from based on what else is on the circuit (I didn't want to pick the engine management circuit for example!). I measured how current much different circuits ACTUALLY drew to pick one with a lot of margin, and did this by using the very handy $13 mini fuse circuit tester from Harbor Freight
But now I'm thinking I should revisit this and put in something cleaner. I always had my eye on the sealed 3 circuit kit from Eastern Beaver
as it is really slick and takes a lot of the work out of it for you. Note it has a switching lead that you connect to a switched location and that controls the relay so it is only closed when the switch is on: