Headlight auto-cutoff Mod

[BatRastard]

Reading about the problems people have starting in cold weather got me thinking about ways to improve starting in general. The obvious improvement would be to reduce the battery load as much as possible when starting.

As soon as you turn the key the battery sees a 6 amp load, all but about .25 amps going to the headlight and tail light. Keeping both off will make more power available to the starter and ignition, a big help in the cold when batteries provide less power. Your battery should last longer, and will recharge sooner.

This mod is both cheap, easy, and reliable.

I installed a horn relay from the junk yard but you can get them at any auto parts store. An old relay is fine as the "normally closed" contacts are used ... if the relay croaks the headlight stays on during starting, no biggee.

Here's the relay, a standard 12v automotive relay.


Pins #30 and #87a are hooked up to the 10amp light circuit, the brown wire going to the fuse block under the seat. On mine I just chopped off the bullet connectors and crimped on some female insulated spade connectors.

Pins #85 and #86 drive the relay and I wired them directly to the starter relay.


I had connectors on hand but quality insulated butt connectors spliced on directly is easier and I would think more reliable.

The relay fits under the seat on top of the airbox.


Total parts should be $10-$15 max ... labor about an hour.

Bat

[puttrench]

I installed a horn relay from the junk yard but you can get them at any auto parts store. An old relay is fine as the "normally closed" contacts are used ... if the relay croaks the headlight stays on during starting, no biggee.
-------------------

Hell of a plan, dont kno why kawie didnt do this from day 1, lot of other skooters have this built in from the factory..

[Zeerx]

I was thinking of doing the same thing because I was having a cold start problem too. If I just put an on/off switch on the headlight circut will it cut off the tail light too? Could you write your mod in a schematic? Cheers.

[BatRastard]

Originally Posted by Zeerx

I was thinking of doing the same thing because I was having a cold start problem too. If I just put an on/off switch on the headlight circut will it cut off the tail light too? Could you write your mod in a schematic? Cheers.

I'm not sure how I'd go about drawing up a schematic but I'll think some on it.

Switching out at the fuse turns off the tail and instrument lights in addition to the headlight. Switching off just the headlight is ok as it has the biggest draw but I don't like the idea of possibly riding without a light.

Ultimately I plan on doing a mod where the headlight had dedicated power that is relay controlled and another relay that keeps all the non-essential loads off when the engine is not running. I also want to install an led on the instrument cluster that will go on whenever the headlight is off.

Bat

[fixer]

if you're using an aftermarket or homebrew wiring harness to dwar power for the headlight directly from the battery, this should be an easy change.

[delkron97]

BatRastard,
r u sayin u just cut the brown wire in half then added plugs on each cut end...then hooked to 30 & 87A.
then same for starter relay wire to 85 & 86?

[krpotter]

Just a quick warning about cheap auto relays. I picked up a couple of them from my local Advance auto parts to use for an extra driving light but they kept screwing up. I finally took one apart and found it full of rust and corrosion from too many stream and puddle crossings (mine were mounted below the headlight). To fix this I just sealed the cap to the base with ordinary old silicone. I think they were really made for use inside a car rather than strapped onto a KLR.

[Scott_Rides_Again]

Nice mod, Bat.

I'm going to do it.

[BatRastard]

Originally Posted by delkron97

BatRastard,
r u sayin u just cut the brown wire in half then added plugs on each cut end...then hooked to 30 & 87A.
then same for starter relay wire to 85 & 86?

Yes, as long as you keep the relay under the seat the brown wires will work on #30 and 87a as they are. You need to add
your own wire at #85 and #86 and run it down to the starter relay to tap in there. The relay doesn't draw much power so the quality of the insulation on the wire you use is more important than the gauge.

Bat

[BatRastard]

Originally Posted by krpotter

Just a quick warning about cheap auto relays. I picked up a couple of them from my local Advance auto parts to use for an extra driving light but they kept screwing up. I finally took one apart and found it full of rust and corrosion from too many stream and puddle crossings (mine were mounted below the headlight). To fix this I just sealed the cap to the base with ordinary old silicone. I think they were really made for use inside a car rather than strapped onto a KLR.

Good point. These relays are normally high and dry under the hood of a car. A little bead of RTV at the base will make them KLR proof. (Tho' you may have other problems running through a stream deeper than the airbox!)

Because the contacts used are closed when the relay is off, a relay failure is not a problem. On rare occasion a relay contact can stick but usually that's from too much current. Never say never tho' ... I'll be modding my mod.

Thanks,

Bat

[delkron97]

BatRastard,
piece of cake man, just finished up. had a spare relay out in garage...everything works perfectly. soon as i hit starter...head light and tail light goes out and comes back on soon as i release starter button.
turns out, it is same procedure as hookin up auto comp releases on ss 124 engine i installed in harey i used to have.
great mod...thanks for heads up...i dig it.

[BatRastard]

Originally Posted by delkron97

BatRastard,
piece of cake man, just finished up. had a spare relay out in garage...everything works perfectly. soon as i hit starter...head light and tail light goes out and comes back on soon as i release starter button.
turns out, it is same procedure as hookin up auto comp releases on ss 124 engine i installed in harey i used to have.
great mod...thanks for heads up...i dig it.

Cool, nothing better than a mod from scrounged up parts!

Bat

[SDMF_Reaps]

Originally Posted by 2004 KLR 650 manual page 23:

NOTE

The tail and license plate lights are on
whenever the ignition key is in the ON
position. The headlight goes on when
the stater button is released after
starting the engine. To avoid battery
discharge, always stat the engine im-
mediately after turning the ignition key
to "ON".

I've always wondered about this. I've seen other bikes doing you yours now does and wondered why mine doesn't. It makes so much sense. I remembered reading something about this in the manual and had to find and quote it. Unfortunately my memory was wrong and it is clear the light was only intended to go off when the starter button was depressed. I thought it was to be off until the bike started.

Edit:

Forgot to mention something:
Great post!!

[wingerr]

Originally Posted by SDMF_Reaps

I've always wondered about this. I've seen other bikes doing you yours now does and wondered why mine doesn't. It makes so much sense. I remembered reading something about this in the manual and had to find and quote it. Unfortunately my memory was wrong and it is clear the light was only intended to go off when the starter button was depressed. I thought it was to be off until the bike started.

That's the kind of setup on an 85 Ninja, where the headlight stays off until after you press and release the starter; then it stays on. It stays off from the time you turn the ignition on until you start it up, which is a bit better, since you don't get that initial drain right after switching on. The KLR can be retrofitted to do that with a few relays; I drew out a circuit to do it but never bothered to try it yet. I was thinking something simpler like just cutting off the headlight circuit when the neutral switch is on, so when I'm starting it up and idling the headlights will remain off even after starting.
I'd add an override switch to keep the lights on in situations if I need to be sitting in traffic in neutral.

BTW, relays can definitely still fail even in the off position when using the normally closed contacts; the contacts can corrode just as easily and fail to pass the current. If anything, they may even be more prone to failure than the normally open contacts because they have lower contact force. Usually the NC contacts are rated for slightly lower current capability than the NO contacts, because they only have spring tension holding them closed, as opposed to the coil pull when energized. Sealing the relays would definitely be a good idea in a KLR environment-

[BatRastard]

Originally Posted by wingerr

BTW, relays can definitely still fail even in the off position when using the normally closed contacts; the contacts can corrode just as easily and fail to pass the current. If anything, they may even be more prone to failure than the normally open contacts because they have lower contact force. Usually the NC contacts are rated for slightly lower current capability than the NO contacts, because they only have spring tension holding them closed, as opposed to the coil pull when energized. Sealing the relays would definitely be a good idea in a KLR environment-

True, the contacts can fail with sufficient corrosion. Using the normally closed contacts are more reliable primarily in
a situation where the coil in the relay fails. The standard horn relay is rated at 20 amps on the normally closed and 30 amps for normally open.

Sealing the base of the relay is a great idea, and if you get a relay from a junk yard it would be a good idea to pop the cover off and inspect the contacts.

It sure is great to have a forum like this where mods get presented and improvements to the idea added on.

Later,

Bat