Disclaimer first: I am not a qualified electrician and make no claim to be one. The only thing I’m sure of when it comes to electrics is don’t lick light switches. This write-up is based on what I did to my bike and is not intended as a definitive guide to all things electrical.

That said, having finished this job, which I started as very much an electrical novice, I now feel a lot more confident in tackling electrical jobs and have a greater understanding of my bikes electrics.

The purpose of the relay is to supply a switched (on & off with the ignition) 12v feed which can be used to power any aftermarket accessories such as:

• Heated grips
• 12v lighter sockets
• and heated clothing..

The benefits of wiring any items in this fashion are, minimal hacking of standard loom, reduced chance of overloading standard wiring and ease of isolation in case of electrical/mechanical problems. I’m sure there are more, but it was these which appealed to me.

Tools & Components



All the items I used were from either Maplins, Halfords or just kicking around in the garage. The only tools used which were remotely specialist, was a 12v digi-meter and a soldering iron. The rest was standard garage stuff. The wire used was red or black 17amp. A tad heavy duty but its what I had in the garage, although 8amp (the next size down in Halfords) was a bit thin and fiddly so I probably would have bought 17amp anyway.

Having owned a few bikes which could only be described as ‘scotch-lock central’ and which regularly gave me loose connection type grief I decided this job would be soldered. This meant learning to solder. So I did a Google, found a guide, cut a few lengths of wire and practiced until I was OK at soldering. Quite easy really so long as everything is clean and you remember to ‘tin’ the nib of the iron as this helps transfer heat far more effectively. Splicing into existing wires is pretty easy.

Strip the insulation



And twist on the second wire



….and solder.

Where to mount the relay?

Next to the fuse box seemed logical as this is also near the battery, and there is plenty of room under the r/h side panel. I settled on drilling a small hole and bolting through the plastic under-tray type bit.



12v live from the battery

This is the feed for connection 30. I wanted to fuse it, so the bike and/or gadgets would have some protection. If you look in the fuse box, there is a spare hole at one end just waiting to be used. Alternatively, Maplins do an in-line fuse holder which you could use if you don’t fancy touching the fuse box. I made up some connectors and used this as my fuse holder.




If you push the female spade connectors (one from each wire) up into the back of the fuse box, they will fit OK, if a little loosely but they are held firmly in place by the fuse. After blowing a few fuses, I found pushing an electrical screwdriver into the back of the fuse box was a good way of holding the connectors in place while I fitted a new one. You need to make sure the connectors are facing in opposite directions to make getting the fuse in a bit easier as there is a bit of an offset.



It’s a bit fiddly, but worth it as it gives a nice tidy solution. The ring connector goes to the positive battery terminal, and the other spade to the relay (30). I’ve used a 5amp fuse based on what I’ve got wired in (more on this later).



Switched Live

Whilst the fuse box is off, now is a good time to get the ignition switched feed which will go to connector 86 on the relay. Finding a switched live is dead easy, using a multi-meter poke about in various connectors until you find one which is putting out about 12v but only when the ignition is on. Then find a suitable point on that wire to splice in. One thing worth considering is the thickness of wire you are attempting to splice into, as too thin a wire is difficult to remove the insulation from without accidentally cutting the wire in half. (No I didn’t do this!)

I have used a switched live from the fuse box. If you turn the box over you will see from the picture the red/black wire I have used. If you look closely you can see that the wire is actually feeding three sockets. I have already removed the insulation, ready for soldering. Don’t do what I did and identify the wire, go and make a cup of tea and then come back and splice into the wrong red wire (see the black insulation tape!!!)
It is v annoying!



Connect the other end to relay terminal 86 and it should look something like this



Note the negative (85) bolted to the frame – you could run it to the battery if you prefer

The two remaining connectors are 87 & 87a. I have blanked 87a with an insulated connector for now as I have no use for it yet but will probably get round to fitting an aux 12v socket to it.

The finished item



I have since shrink wrapped all the connectors but insulating tape would be OK too. I have looped the 12v cable from 87 once around the fuse box before running it up to the front of the bike. This is so I have a spare few inches (ahem), easily accessible to splice into in the future

87 now runs up to the front of the bike to a 12v ciggie socket. I have also spliced into it to power my heated grips and autocom.








Fuse selection

The fuse you use is dependant on what you are powering. Most manufacturers’ instructions will give you some idea of power usage and you can then make an educated guess at which fuse. It’s probably better to start low, and see if it blows than put a 20 amp in and see your PDA and phone melt before the fuse knows what day it is.

I have:

• Heated grips (Oxford say less than 2amp)
• Autocom (My guess is less than 1 amp)
• 12v socket to power PDA (2 amp - Dell X50 is a thirsty bugger and will pull nearly 2 amps if the screen is on brightest!)

So by my reckoning that is about 5 amps. So I fitted a 5 amp fuse, turned everything on and stood back. Nothing fizzed or popped so I’ve left it at that for now.


Cigarette Lighter Socket

The plastic box and socket came from Maplins.





I drilled the box using a hole saw and fitted the socket with small self-tappers



The negative from the socket is bolted to the frame.The box is held on with sticky fixers for now and the brass screws are now black.





So there you have it.