Follow these instructions to build and configure an auxiliary power source for your motorcycle accessories. Relay installations help optimize battery use.
There are all kinds of electrical luxuries out there that can bring greater comfort to long distance motorcycle touring. One of the most popular additions is that of heated grips. These power gobblers (not really) are the poster children for why I’ve created this page.
My older, lower-displacement motorbike makes use of Hot Grips. They’re pretty amazing but a little pricey. For my latest addition to the collection (an ’03 Suzuki Bandit 1200S), I’ve decided to follow a more experienced friend’s advice and order Symtec grip heaters. Their user reviews suggest they’re of equal+ caliber.
That’s not the point, though. In doing a bit of installation research, I’m reminded of the wiring chaos that my prior setup demands. Knowing that I plan on installing other gizmos as well, this marks the perfect moment to, rather than repeatedly hack into my motorcycle’s wiring or throw fifty ring connectors onto my battery, create an AUXILIARY RELAY.
It’s actually a lot easier than you might think – and – I’ve already made all of your mistakes for you. Humbly, I’m making use of my very first relay setup as an example. Perhaps in the future I’ll create a comparison page to suggest newfound understanding.
If this seems too difficult or time consuming and you’d like for me to build one for you, click here.
What To Buy:
- ATC blade fuse panel
- 10 amp ATC blade fuse
- 20 amp ATM blade fuse
- inline ATM blade fuse holder
- terminal connectors
- heat shrink tubing
- 4 position dual row barrier strip
- 8 position jumper
- 30 amp Bosch relay (the relay I use is prewired and color coded)
- 10, 12 and18 gauge electrical wire
- quick splice wire connector
- 1’x1′ piece of 1/4″ plexiglass
- medium grit sand paper
- electrical tape (get the good stuff, not the cheap crap)
- electrical solder
- alligator clips
Tools You’ll Use:
- table saw – or – jigsaw
- cordless drill
- drill bits
- phillips head screw driver
- combination cutter/stripper/crimper
- soldering iron
- pocket lighter
- electric multimeter (should have continuity option)
Let’s Do This:
If your relay didn’t come with color coded wiring, tape and label each line accordingly. Otherwise, be sure the following colors apply. If they don’t, substitute your colors in place of what I’ve listed below.
(1) Plug the relay’s male hub into the female (pre-wired) outlet. Our diagram now uses the following scheme (hopefully):
- 30 = yellow
- 86 = red
- 85 = black
- 87 = brown
- 87a = orange
(2) With your combination cutters (*burp* scissors), cut the relay wires down to the following lengths …
- yellow = 2″
- red = 3″
- black = 1″
- brown = 2″
- orange = 2″
(3) For every relay wire EXCEPT yellow, strip 1/4″ of the vinyl jacketing using your wire strippers. For the yellow line, strip 1/2″. For the inline fuse wire, strip one side by 1/4″ and the other by 1/2″.
(4) Using your color scheme, prepare and set aside the following connectors:
- yellow = n/a (leave the wire bare)
- red = female side of an 18 gauge (red) quick disconnect
- black = small, 12 gauge (blue) battery ring connector
- brown = normal, 10 gauge (yellow) battery ring connector
- orange = female side of a 10 gauge (yellow) quick disconnect
(5) Use your dremel to grind down the 12 gauge (blue) battery ring connector so that it fits more easily into the barrier strip.
(6) One wire at a time, use the info from step 4 to go through the motions:
- cut a 1″ piece of heat shrink tubing that’s wide enough to encompass the connector’s neck
- place the piece of heat shrink over the wire, as far away from the bare line as possible
- insert the wire into it’s connector so that you can see the tip peeking through
- using your combination crimpers, crimp the metal around the wire to brace it
- heat the wire with your soldering iron where it peeks through
- apply a small amount of solder (to the WIRE) so that it is molded firmly into position
- once cooled, position the heat shrink tubing around the connector’s neck
- using your pocket lighter, run a flame underneath the heat shrink tubing
- roll the heat shrink tubing over the open flame to balance/reform it
(7) Using the same techniques as above, apply a normal sized, 12 gauge battery ring connector to the 1/4″ side of the inline fuse holder. Leave the 1/2″ side bare.
(8) For the yellow line, prepare/position heat shrink tubing just as you did above. Next, take the 1/2″ stripped side of your inline fuse holder and braid it’s bare wire with that of the 1/2″ stripped section of yellow relay wire. Using two alligator clips, clamp the two wires together and apply direct, compressed heat via your soldering iron.
Apply an ample amount of solder to infuse both lines. Be sure and avoid soldering the alligator clips! Reposition and apply the heat shrink tubing, completely covering the bare wire and hardened solder.
(9) Cut your 8-position jumper down to 4 so that it fits more sensibly into your barrier strip. Insert the jumper into the barrier strip and gently tighten it into position.
(10) Install a 30 amp blade fuse into the inline fuse holder.
(11) Using a table (or jig) saw, cut a 5″ x 6″ piece of plexiglass. Sand any rough edges to give it a smooth, uniform finish. Please note that the dimensions and placement depend heavily on the make/model of your motorcycle. BE READY TO IMPROVISE.
(12) This next photo (the same one from above) might seem chaotic. Ignore the wires and pay close attention to where the components are positioned. To get the same general placement, lay the components onto the plaque where they belong, run a small drill bit through each individual mounting hole and drill just gently enough to leave a small, centered mark. Two diagonal mounting points per component should be more than enough (the green dots). Four is overkill, if you ask me.
- brown line connects to the main power rod on the fuse panel
- black line curls (hard left) and fastens into the barrier strip
- orange line gets covered with a rubber cap of some kind (ignore what I did)
(14) Using a multimeter in continuity mode, feel free to test each connection as you see fit. Some may not work because they don’t activate unless the key is in the ‘on’ position. We’ll get to that.
(15) Mounting the panel might be tricky. This is the part where you have to be both considerate and creative. What works? What’s safe? What’s stable? Once you’ve decided where things belong, drill the necessary holes into your plexiglass and mount your system. On my Bandit 1200, I have a couple unused, threaded holes in the frame that work perfectly with a pair of modified ‘L’ brackets. They’re converted into ‘Z’ brackets by JB-Welding a screw/nut tightly between at the threads. Observe my grand ingenuity:
(16) Two wires remain to be fashioned but more info is required. Measure the distance between your battery’s ground (-) and whichever barrier strip slot you’d like it to be connected to. Cut a section of black 10 gauge line to length, strip the vinyl jacketing on both sides by 1/4″ and apply battery ring adaptors (small 10 gauge on one side, normal 10 gauge on the other). You should grind the smaller ring down to fit the barrier just like before. Use step #6 as a process reference.
(17) Now measure the distance between your tail light and the RED line of the relay. Again, cut to suit (this time using 18 gauge rather than 10). You only need to splice one side of this line to 1/4″ before applying the MALE side of a wire quick connect.
(18) Let’s ready the panel for use.
- 10 gauge wire connects the barrier strip to the battery ground (-)
- yellow line, which becomes the inline fuse holder, connects to the battery hot/red (+)
- 18 gauge wire connects to any tail light source that receives constant power (via quick splice)
- red line quick connects to 18 gauge wire
(19) Assuming things go according to plan, you’ve got yourself an auxiliary panel! Here’s how we can tell for sure.
- switch your multimeter over to “one higher than” 12 volts, DC mode
- place the 10 amp fuse into the fuse panel
- Turn the key to the ‘on’ position
- put the red pin on the fuse panel connection that has the 10 amp fuse installed
- place the black pin on any of the barrier strip screws
Also, compare your wiring effort to the following diagram …
(20) If this works … eureka. You’re in business. Have a beer.
If you’d like for us to build and ship a custom auxiliary power relay ($75) that’s tailored specifically to your motorcycle, please contact us directly. Be sure to include the width, length and height of your total available installation space as well as any data you like about what electronics you’ll be connecting to it. The more information we have, the better!
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