Voltage drop and Headlight output: Decreases lighting output by as much as 20%

Near a bulb's working design Voltage, a drop of only a half of a Volt results in a halogen bulb producing much less light. Many bikes have shown a 1 or even 2 Volt drop at the bulb, and I have confirmed this on my own Bikes. And this is also on new or like new Bikes.

After installing a relay kit, you will have a drop of ~.1 Volt, That's 1/10th of a Volt in case you miss the decimal.

There is always going to be some Voltage drop, This is normal with any switch contact. But this is about the minimum possible. This low Voltage drop is the proof that the system is a good one. All the wiring, connectors, and components are working as they should.

Headlight and Starter Switch’s

Headlight switches and starter (this is how your headlight turns off when you hit the starter button) switch’s are usually a weak part of a bike's electrical system. Even with a stock 55/60 watt bulb, headlight switches and connectors can break down early in a bike's life. This is because ALL of the electricity that goes to your headlight bulb is passing through those little switch contacts in your handlebar switch units.

Note: Some bikes do actually come with headlight relays, but the number is few. Even on newer Bikes.

When you are done completing this install, your headlights will function as they did with the dimming while using the starter button, everything is completely plug and play, no cutting or splicing here. for a complete harness you can purchase one here http://www.cycleterminal.com/headlight-kits.html

You can also pick up a harness for aftermarket horns and fuse boxes.

So here I decided to clean up some old wiring I had added to the bike over the last couple years, and install one of my premade wiring kits, so I can get some voltage drop readings at the bulb before and after the relay harness, and photos showing easy the harness is to install.

First we will get some voltage readings at the battery with the Bike running at idle. 

And then the Headlight bulb with the Bike running at idle. 

A full 1 volt drop in voltage at the Bulb.

Here I am going to install the relay harness along with some other goodies that we will not be getting into, but they are all built into a single plug and play harness with 4 relays and only 2 wires running to a secondary fuse box near the battery. Normally you will connect the headlight relay harness directly to your battery.

I have a 7inch headlight housing so there is plenty of room in this one for all these relays I am adding.

There is also a harness for fairing mount and dual H4's, I am working on the H13 now but having problems getting wire seals for the special connectors for those bulbs.

The coil of wire at the bottom is for a set of switches I use for additional running lights, and strip LEDS under the fenders and tank.

Here you can see the relay's and the single harness that runs through the back of the headlight housing.

This will run along the frame to the back of the bike with the main harness.

 Next we will connect the bikes original H4 bulb connector to the relay harness H4 coupler.

 And then cover it with a large peice of shrink tube, as the orignal connector wiring is somewhat exposed.

Now we are going to get everything tied up into place and tucked back in the housing so the headlamp will fit back in properly, and we can make the rest of our connections and finish routing the harness to the battery. It is very important to make sure this is secured well, you dont want any flexing of the wiring at the base of the relays. And we dont need any rattles that wernt there before we started.

  

You want to try and make sure you run this with the main harness if possible. and give yourself plenty of harness to turn from lock to lock without pulling or binding of the harness.

              

I ran the wiring right down the center of the frame with the main harness on the bike, Cut it to length and then crimped my terminals for this connector here.

This connector here happens to be powered at all times, and does not run through a relay I have set up on the secondary fuse box.  

 Here is a picture of my secondary fuse box, it lays under the left side cover, wrapped with a piece of 3M adhsive lined foam to keep it from rattling around.

 Here is a photo of what I cleaned up, as most of the relays in the headlight were under the seat at one time. Now only the horn relay, main fuse for the secondary fuse box and some connectors reside under there. Along with another fuse for the tender cable.

Voltage reading at the battery with the bike idling (this was after a coolant change as well, so it had been warmed up and idling a little higher this time)
These reading were taken at the battery tender connector.

And at the headlight bulb connector at idle.

Looking good with .05 voltage drop at the bulb.

If interested in a harness or making one yourself, and components can be purchased at www.cycleterminal.com

Thanks I hope this can provide someone with help in doing it themselves.