Disconnecting one headlight

[Auron]

I'm sure I'll get flamed for this big time so I won't bother with my reasoning. The bottom line is I'd like to do it, but I've read here that when one burns out, the other follows but I can't understand why. Mechanically speaking, is this a bad idea?

 

[Chuck35]

Do you have only one eye?

 

[majicmaker]

Why would you wanna do that?

 

[mdisher]

Not sure why you'd want to do this but it would seem to me that you could just unplug one, leaving the bulb in the headlight, and if it's long term I'd probably wrap up the connector in something that you could un-do when you wanted to activate it and plug it back in.

Not a horrible job, but also not easy to get to on the side of the road in the dark.

 

[a.droid]

Why would you wanna do that?

Maybe to look like other bikes which do that... Suzuki I believe.

 

[wfooshee]

Some bikes use one light for low beam and the other for high beam, rather than use dual-filament bulbs. It's not a feature, it's a cheap-*** way to build a bike.

As for the point about when one fails, the other fails shortly, who knows why, but it's something enough of us have experienced to call it a fact. If the idea is to "preserve" one of the lights for when the first goes out, what are you going to do when the one you left fails, ride around in the dark? Or crash?

Why couldn't you have posted this on Friday?

 

[ridernotbiker]

I'm puzzled too, but maybe a toggle switch spiced into that particlar headlight and placed at a location that suits you. A flip will restore juice when you want it without problem.

 

[Constant Mesh]

My second lamp died almost 8K miles after the first one. When a lamp dies its current goes to zero and the voltage increases in the headlight circuit -- reduced voltage drop. The remaining lamp receives a bit higher voltage and its wattage increases by a squared relationship -- V squared.

 

[Chuck35]

i suppose you could set up a DPDT switch so the lo on one and the hi on the other was active, then switch them at will.

 

[Auron]

OK so, I might as well explain myself. I'm looking for a way to conserve energy drawn from the battery. Try to understand I fought charging problems on my XX the entire time I owned it, and it had a 460 watt alternator so I'm kinda spooked about the whole idea. The FJR itself has even more watts drawn, and I didn't even have heated gear on my old bike. So if I'm powering my ipod, radar, GPS and heated gear, isn't this going to overtax the system?

 

[TomInPA]

My second lamp died almost 8K miles after the first one. When a lamp dies its current goes to zero and the voltage increases in the headlight circuit -- reduced voltage drop. The remaining lamp receives a bit higher voltage and its wattage increases by a squared relationship -- V squared.

during operation the electrical system carries a maximum voltage of 14.2 VDC regardless of how many lamps run. Having one burn out does not increase the voltage in the circuit unless the bike is somehow running below stator/RR output voltage.

We have disconnected lights when a stator fails or there is some reason to conserve power, i.e. to divert loads elsewhere. In my opinion, it's better to convert to HID and consume 35 watts per light than unplug one. More light, less power use. Works great for me.

 

[TomInPA]

OK so, I might as well explain myself. I'm looking for a way to conserve energy drawn from the battery. Try to understand I fought charging problems on my XX the entire time I owned it, and it had a 460 watt alternator so I'm kinda spooked about the whole idea. The FJR itself has even more watts drawn, and I didn't even have heated gear on my old bike. So if I'm powering my ipod, radar, GPS and heated gear, isn't this going to overtax the system?

Install a volt meter and work with what you have. There are other ways to eliminate losses in the system. FWIW I operate that much gear and more on my 2005 with no problem....HID headlights, Kristas, Warm N Safe gear, autocom/GPS/RD/stereo source/ bike to bike radio etc.

I recommend watching Apollo 13 for energy saving ideas.

 

[Auron]

What's the easiest, and least expensive way to use a headlight bulb that draws less watts? The HID conversion would only be a last result, mostly because I'm so tired if putting money into this bike

I just want to ride and I keep telling myself I'm done adding things

 

[Ignacio]

The FJR itself has even more watts drawn, and I didn't even have heated gear on my old bike. So if I'm powering my ipod, radar, GPS and heated gear, isn't this going to overtax the system?

I don't think that's a valid assumption. Have you installed a voltmeter and see it is actually being stressed? The iPod, GPS, and radar are like throwing bricks in the Grand Canyon...they make *little* difference. The Gen 2 FJR has 590 watts (100 more than Gen 1) and even a set of heated gear isn't going to put you in a deficit situation.

Invest in a Datel or put on a volt meter instead of engaging in superstition.

 

[900gc]

What's the easiest, and least expensive way to use a headlight bulb that draws less watts? The HID conversion would only be a last result, mostly because I'm so tired if putting money into this bike

I just want to ride and I keep telling myself I'm done adding things

Well if you must:

https://click-parts.co.uk/files/details.php?id=595

But that's like riding with a smoke shield at night. CSS. Don't you like to see well when you ride at night or is all your riding urban where street lights do most of the work?

+1 on what Ignacio said. With around 200 reserve watts on a Gen. 2, you are nowhere near taxing the charging system with what you are running.

 

[Auron]

I didn't know there was so much power in reserve but I sure am glad I asked. I guess I overlooked the fact that Yamaha can actually build a competent charging system. Wish I could say the same for Honda.

 

[Fred W]

To answer the original (inferred) question: No, unplugging one of your headlights will not cause the other to burn out (much) quicker. The reason that the second headlight seems to burn out right after the first one is because they have the exact same runtime on them. The filament material of an incandescent bulb (even one surrounded by halogen gas) has a finite and predictable number of lumen-hours when new.

Since both of your headlights receive the same exact applied voltage for the same exact amount of time they will have very similar lives.

The idea that the increased voltage on the second bulb (after the first one burns open) will hasten its demise is true, but to a relatively insignificant extent. The difference in applied voltage will occur due to the reduced current draw of only one headlight in parallel, which will result in less voltage drop on the distributed resistances of the wiring harness. So, just throwing out some numbers here, if your charging system is healthy and putting out 14.2V, with both headlights running you may be getting 13.6V to the bulbs with both headlights running and it may go up to 13.8V when the first one burned out. In other words the lamps power will be boosted by a bit less than 1.5%, and the lifespan of that bulb will be hastened by that same amount. Hardly something to worry about.

35 watt HIDs consume more than 35 watts each due to losses in the ignitor/ballast to generate the high voltage needed for the Xenon gas discharge. Using them will save you a few watts over the 50/55W halogens, but it is hardly worth doing that for that reason. The reason I have them installed is because it makes you stand out more in the daylight, and gives more light down the road at night. It also takes the entire load current of the headlights off of the ignition switch, which (as all 2nd gen owners know) is a good idea.

On my power starved 1st Gen FJR (w/ HID headlights) I've found that I can run two 90 watt jacket liners (nominally being pulsed at ~50% duty cycle) and two pairs of heated gloves along with all of the other normally found rider electronica (intercom system, GPS, radar detector, cell phones a-chargin', etc.) and still maintain an adequate battery charging voltage. Of course I do have a Datel panel voltmeter to keep an eye on that. But for your second gen the load you propose should be a breeze.

 

[wfooshee]

Another case of manufacturing stuff to worry about.

Plenty of juice in that Gen-II.

And see, if you'd actually said that in the OP instead of "I won't bother with my reasoning," you would have had an instant and correct response of "No need, you have plenty of watts," instead of all the guesswork of people trying to figure out what it was you were after.

 

[deanw]

Other than why unhook one headlight, here's why not:

Because every third cager will insist on telling you that one headlight is burned out.