i added an acc socket when i added the relay. so it is tied into the same setup.
1) run a power lead from the battery forward. make sure to mount a fuse as close to the battery as you can. that way if it breaks anywhere along its length it'll take out the fuse rather than melting the wire.
2) install a standard 15amp automotive relay up front somewhere. **what's a relay?**.
2b) ok now you've gone down below and know how a relay works i'll help you out a little with this a, b, c shit... on almost all (all good ones) relays there is a standard in terminal naming... terminals 87 and 87a are the high current power outs. 87 is the one that is switched 87a is the one you can tape up. terminal 30 is the terminal you want connected to your battery and fused wire. 85 and 86 are the low current electro magnet. piece of cake....
3) connect the fused battery lead to terminal 30 on your relay. leave the fuse out until you're done wiring the whole thing.
4) connect a wire from 87 on your relay to one lead on each grip heater. you're also going to want a toggle switch in this line to turn the heaters on and off. if you really want to get fancy you can put an on-off-on toggle with a resistor in one wire to give you a high and low heat option.
5) connect the other lead(s) of grip heaters to a good chasis ground. some guys will tell you to put your grip heater switch here. don't! if there is a failure in the element, or anything upstream you could have bad things happen.
6) connect a lead from terminal 86 on your relay to the good chassis ground.
7) here's the fun part. you need to find a switched +12v power source to flip the electromagnet on and off when you turn the key. you're going to need a multimeter for this job, or someone who has done it and can point you to an exact wire (i'll go find one later if nobody else bucks up). what you need is a wire that is hot when your ignition switch is on, and dead when the switch is off. once you get that wire hook it up to the 85 terminal on your relay.
pop a small fuse in the fuse block to test everything (like a 1 amp), then once you're sure everything works well pop in the size to match the wire and relay (prolly a 15 amp).
if you ever need power for any other acessories you can jump off the lead hooked to terminal 87. no need to fuse anything beyond that point because you already have a fuse back by your battery.
**what's a relay?** - a relay is a switch that transfers high amounts of current on one side and is controlled by a low current on the other. when the low current side is energized it activates and electromagnet that pulls in the high current side. in the diagram below v1 and v2 are the low current side. the "common terminal "c" is where you want to put the lead from your battery. it's hot all the time... terminal "a" is hot any time your v1 and v2 are not energized (tape that guy up... you don't need it right now). terminal "b" is your switched high current power to run whatever you're powering.