Headlight wiring

[nakman]

I am starting over on wiring for my headlight. Have a new dual sport kit with hi/lo switch, but those are just for completing the loop, there's no power to it, I need a power feed. I want to abandon the stock wiring and start over for the headlight, not only for ease of future diagnosis, but also so I can turn the headlight on without turning the bike on.

I plan to run straight from the battery- would you suggest a relay setup, similar to fog lights on a truck? Or is this current draw so low that it won't matter much if the juice has to flow through the switch..

 

[subzali]

Do you have the service manual for the bike? There's a wiring diagram in it that might give you some ideas...

...it doesn't look to me like the factory wiring has a relay...

 

[nakman]

Do you have the service manual for the bike? There's a wiring diagram in it that might give you some ideas...

Yep, but everything in the stock wiring only comes on after the bike is running.

 

[DaveInDenver]

The current I'd expect is fairly decent being that it's a 6V system, right? Even if it's a fairly low power light, say 35W, that's around 6A. Well, that assumes it's an incandescent bulb, if it's LED or something then it would be quite a bit lower.

I like to always use relays, although it's not like the runs are long on a motorcycle. But it does simplify the high current side to just two wires and makes the control side wiring lighter, which I would assume on handlebars might be important since trying to connect 14AWG would be a PITA compared to 22AWG.

 

[nakman]

It is a H4 halogen bulb with high and low beam – 12V 35W/35W. I am not sure what 35/35 means, does that imply 70 watts when I switch to Hi Beam?

So relay gets 12v from the battery (30), a feed in from the tail light running light or horn feed (85), a ground (86) and then a feed out to the white wire running into my hi/lo switch (87), then the black and blue wires coming out of the hi/lo switch running to the Hi and Lo terminals on the headlight. This still funnels the whole thing through the hi/lo switch though, but I'm not sure how to avoid that without two more relays- one hi and one lo, which just seems excessive. The wiring in the switch is probably in the 18-20ga. thickness, which is likely triple compared to what's in the stock harness.

Here's a simple diagram of a different setup, but just to refresh you on what terminals do what.

 

[Red_Chili]

35W in low, 35W in high. Different beam is due to focus. If you want REALLY bright (and sap your battery and lighting coil, I rather suspect you do not have a 200W aftermarket wind) you can put them both on at once. Probably not.

Be sure you don't have a 12VAC lighting coil, and a 12VDC batt charging coil. I don't know Katooms but it's been done. Dem Germans have been known to go their own way.

You can get aftermarket handlebar lighting switches that look factory. I run one.

 

[Red_Chili]

Here's an example from a google search. Not quite right but close.
http://www.motopartsmax.com/index.php/main_page/product_info/products_id/15698

Better:
http://www.procycle.us/images/dualsport/comboswitch_mini.jpg

 

[nakman]

Ok cool thanks Bill, so if its 35w either way then I'm definitely not worried about running that through the handlebar switch. I'm all DC, but that's not universal even with KTM's, in fact I believe Bruce's bike goes both ways.

And reason #23 for running the headlight straight to the battery is, I am fairly sure that's a DC setup that even I could later diagnose.

I do have a 100w Stator http://www.trailtech.net/SR-8310.html

edit: Yes, my switch looks just like that "better" one.. but I'm not sure I've got the LED on top, will look tonight to see.

 

[DaveInDenver]

This still funnels the whole thing through the hi/lo switch though, but I'm not sure how to avoid that without two more relays- one hi and one lo, which just seems excessive.

That's what the 87A terminal is for on the relay, 87 is NO, 87A is NC. So it takes just two relays. The first is the power on/off and the second toggles between low and high. Bosch figured that out in like 1962 when they designed it.

 

[Red_Chili]

There's a good reason NOT to run it off your battery. You lose 35W draw while you are trying to estart a dead motor.

As soon as you trace out that hot lead to your lighting coil, you will have gained any troubleshooting insight needed in the future. That's the way to go.

 

[nakman]

Dave what does NO and NC mean.. not open and not closed?


Bill I have a switch for that- the on/off switch next to the starter button will kill all lighting, and makes all lighting completely optional. Another reason for going this route.

 

[DaveInDenver]

Normally Open, Normally Closed.

When the relay coil is not energized, terminal 87A is connected to 30. When you power the relay coil, terminal 87 connects to 30 and 87A opens. This is why it's known as a SPDT, Single Pole, Double Throw. 'Normally' is a term to describe the relay in it's unpowered configuration, think of it as the resting state.

As an on/off (relay #1), you use hot to 30 and switched load to 87.

Connect 87 on relay #1 to 30 on relay #2.

As a high/low (relay #2), you put low beam on 87A and high beam on 87.

Or in your described system, you would just use terminal 30 to the kill-switched lighting and your switch would toggle between high-low rather than on-off.

Substitute AUX Light for low and FLUSHMOUNT for high beam.

 

[Red_Chili]

Nak, you really don't want to run it off your batt. AMHIK.

 

[nakman]

Nak, you really don't want to run it off your batt. AMHIK.

What downside am I not considering? I want to have full control- lights on when the bike isn't, lights off when the bike is, or both on/both off. If I leave my lights on and my battery dies I deserved that. what else is there?




Dave back on the relay thing... I haven't been around since 1962 so am a little slow perhaps. Is the benefit of the second relay so I don't need to run 35w through the switch?

It's an either/or between 87 and 87a, correct? Power to 85 flips it between those.. so my handlebar switch high beam wire is going to trip #85, and I just wouldn't hook up the low beam, is that what you're saying? Resulting in default low beam, switched hi beam. But both are off with relay #1 being switched off. Ok I think I get it now..

 

[DaveInDenver]

Dave back on the relay thing... I haven't been around since 1962 so am a little slow perhaps. Is the benefit of the second relay so I don't need to run 35w through the switch?

It's an either/or between 87 and 87a, correct? Power to 85 flips it between those.. so my handlebar switch high beam wire is going to trip #85, and I just wouldn't hook up the low beam, is that what you're saying? Resulting in default low beam, switched hi beam. But both are off with relay #1 being switched off. Ok I think I get it now..

Yes. You have a kill switch and the second relay (e.g. #1 in the description) is there so that you do not switch high current directly.

You have it right, what's on terminal 30 goes to 87 or 87A depending on the state of the coil. So you have a high beam switch that when off gives you low beam and when on selects high beam. It toggles between the two.

Remember relays are electroMECHANICAL devices, so they do things mechanically that are reactions to electrical changes. Energize the coil and you overcome a spring, which reacts oppositely when you de-energize the coil.

I can add that if you wanted, it would not be difficult to wire this so that you can use a momentary switch (e.g. push to switch to high, push again to switch back to low) that also resets to low beam when the power is removed.

 

[nakman]

Right, my on/off relay #1 will get a trigger from my on/off switch on the handlebars. Won't be from the kill switch though, more than likely the horn- just something that's off when the switch is off, and +12v when the switch is on.

Only downside to this is the "low" position on the headlight control really won't do anything- but then again I'd never have to flip it to off either for that matter. It'll be in low all the time, in both off and low, but then switch to hi when I switch to hi. I guess I could make low switch on some lower power thing that I wouldn't mind running through the switch, and being disabled with hi beams..

 

[rover67]

you could wire it so that the power from the stator energizes the relay. that way it would only light the lights if you had a charge. keep the lights wired to the battery.

nice thing about our bikes is we have kick starts and they aren't 600cc's so if the battery dies it's not THAT big of a deal. also a 100w stator is gonna charge the battery pretty quick.

I liked having the lights wired so they'd run even if the motor was off though, helps with a night time situation where you need to dismount, shut the motor off to talk and find your way type of thing. nice when your flash light is buried in the pack and yo ustill need light.

 

[DaveInDenver]

Just wondering out loud, would there ever be the situation you'd want the opposite (lights off at night)? Personally I'd like to have control over them, I'm not a big fan of daytime running lights in cars for example. Pulling into a commercial campground at night I like being able to go with just running lights if I can to not disturb other campers.

 

[nakman]

It's like a center diff in an awd vehicle- you want every option available to you, not just low range.

What if you shut your bike off at dusk/almost dark to let some hikers walk by... the lights might be nice.

What if you wanted to idle outside work at night while you ran back in to get your phone... No lights might be nice.

And sure, high speed getaways under cover of darkness is always a plus!

what if you dropped your headlamp over by your tent- yeah a quick light from the bike is fast& easy, but no need to wake the camp

 

[60wag]

My lighting is AC. The voltage regulator makes DC to charge the battery to run the starter. The DC circuit has the odometer computer, the horn and the cooling fan as well. I can't run my lights with the motor off, but I also can't forget to turn something off and kill the battery. I do have a switch on the headlight so I can turn it off so the charging system can be dedicated to topping the battery or running the cooling fan.

I didn't bother with a headlight relay. I recently went from a 34watt H4 bulb to a 55watt H4 bulb. It should draw about 4.5 amps if the AC is around 12V. I think the switches are up to it. I actually have two switches: an on/off and a high/low. The 55watt is noticeably brighter than the 35w was. My reflector and lens is def' not a high performance setup but works for now.

Whatever you end up doing, make sure the connections are solid. They will get wet, dusty and be subjected to a lot of vibration. Low cost relays may cut the reliability of the system. Keep it simple so it is sure to function when you need it.