Bicycle LED headlight ???

[**DONOTDELETE**]

I've been working on modding my bicycle headlights for sometime. I do alot of offroad riding at night and I need something that will project about 15'-20'. I have a set of Vistalite headlights (10w halogen) that kills the battery (7.2v 2200mAH) in about two hours. I tried using nine white 6400mcd LEDs, which burned for over 76 hours straight before I turned them off, but was not quite bright enough.I was thinking maybe those new Luxeon Star LEDs would be bright enough but I haven't seen one in action. Does anyone have any ideas? I would be willing to try something other than LEDs, but I have a limited area to mount everything. Thanks in advance.

 

[Saaby]

Perhaps a LED/other combination...with LEDs as your "low beams" so to speak, and then the others could be switched on when you need to see higher...

 

[Orion]

Benski, I just recently purchased a 3 Luxeon Star Bike light, and will let you know how they are when I get to test it.

 

[JollyRoger]

Just two overdriven luxeons should do the trick...and three should be plenty. I have a single luxeon bike light that is pretty bright.
If you use two or three, you should have no problem....plus they'll never burn out!
Just make sure you have them heatsinked well...
Ask Elektrolumens to make one for you and it should be super bright!

 

[snakebite]

i made one from a cheap plastic "bike extras"
$.25 yard sale special.
3 sub c nicads a white ls and 2 486 cpu coolers.works well here for the early morning convenience store runs.about 3 times the usable light of the old dim 2.4v .25a screw base bulb it came with.1heatsink inside on the ls and the other outside bolted/jb welded to the bottom edge of the internal.a neighbor is a bike freak and laughed when he saw it.till i turned it on.
now i get to build him one.
unless you see it running,see the heatsink on the underside, or notice the charging jack it looks just like any cheap hunk of chinese plastic.

 

[gdan66]

Benski,
I've been working on a set of Luxeon MTB lights as a possible setup for an upcoming 24 hr race. I have one LS on the helmet and one on the bars. The helmet one is direct driven from 3 D cells. The bar light is driven from 4 D cells through 3 10ohm resistors in parallel - both setups give about equal brightness. Both LS's are mounted on aluminum heatsinks, but are in plastic cases (cheap headlamps) for weather-resistance. They get a bit warm, especially with new batteries, but are still working fine. The whole setup, both lights, cost less than $100.
As far as the light quality goes for night trail riding - they are not...quite...bright...enough. I went out by myself a few times and thought they were just swell. But then I went out with a friend that has a VistaLight system, too. The two LS's were no match for his 5W flood and 15W spot on his bars and his 25W spot on his helmet. One LS is equivalent to a 5W halogen flood. It's fine for going uphill or riding singletrack at moderate speeds, but for racing you really need a good long-throw spot on the helmet to see far down the trail and the LS just can't provide that. Adding more LS's will of course increase brightness, but also increases cost and amps. Right now the helmet light will give about 6 hours of good riding light, and the bar light about 9. I'm looking into a DC-DC system now which should increase that significantly.

If you're thinking of a dual system - one LS and one halogen - the thing that I've noticed when riding with my buddy is his yellowish halogens seen to "take over" the blue-white diffuse LS beam, totally washing it out. It's almost as if, instead of the light being additive, the halogen covers up the LS light. Strange...but true! I find I seem to see better when riding alone with my LS lights than when the halogen beam keeps flashing across my path.

I'm anxiously awaiting the arrival of the 5W LS, which hopefully will be able to compare with the current halogen technology out there.

Here's a few shots of the helmet light. No shots of the bar light, or night trail beam shots yet...
http://groups.msn.com/RappMTBLights/shoebox.msnw

If you're happy with the light you have from your VistaLights, you might try making your own NiMH battery pack with a higher amp-hour rating to increase your burn time - since you've already got the lights and all...

Good luck,
Dan

 

[**DONOTDELETE**]

Thanks Dan, you pretty much wrapped up everything I wanted to ask. They are for night trail races and I just wanted to squeeze a little more from the vistalites. I dont have a prob with the brightness, just wanted to add to the burn time. Extra batteries tend to add extra weight, and with a 24h race every ounce counts. Maybe I'll wait for the 5w ls, hopefully they will be the answer.

 

[Jonathan]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Benski Gomez:
I have a set of Vistalite headlights (10w halogen) that kills the battery (7.2v 2200mAH) in about two hours.
<HR></BLOCKQUOTE>

I think that you could do quite a bit of optimization in your halogen system before you look into other sorts of lights. It looks to me like your battery and lights are somewhat mismatched.

The Vistalite system is a 6V system, and if you run it at 7.2V then it should run with a higher filament temperature, better light output, higher power, and shorter bulb life time. If you have a 6V 10W bulb (which I believe is actually the rating at something less than 6V, but lets say that the 10W rating is at 6V), then at 6V you would expect a current draw of 1.66A. If you run it at 7.2V, then I would expect the current draw to increase to about 1.85A.

The fact that you get about 2 hours of light out of the 2200mAh battery suggests that for some reason (connector losses, battery internal resistance, etc), the current flow is less that suggested above, suggesting that the voltage applied to the lamp is less than the rated voltage. If this is the case, then the efficiency of the lamp will drop markedly.

Following this chain of reasoning, a 5W halogen lamp run at proper voltage might provide more light than your current system. The way to do this is with aLightbulb Voltage Regulator, a device which takes a higher voltage, and steps it down to a precisely regulated lower voltage for running a halogen lamp. You would have to replace your battery with a higher voltage battery, but this can be done with minimal weight penalty.

It sounds like you have a NiCd battery pack, made with 'Sub-C' cells. These cells are ideal for high current applications, such as power tools and RC race cars. But the high current capability is wasted in a lighting application where you want many hours of light.

If you use the 'long-fat A' sized NiMH cells, made for computer applications, you will get substantially greater energy storage per unit weight; not quite as much as lithium-ion, but pretty darn close. A single long-fat A NiMH cell weighs about as much as a single sub-C NiCd cell, but stores about twice the energy.

So if you change to the NiMH cells, and go to a 8 cell, 9.6V pack, but then use an LVR regulator to provide 6V to the lamp, you will end up with a bright, white light, which should give you between 6 and 8 hours of light. If you could then graft onto that a couple of Luxeons as 'low beams', you'll be set for the entire night.

The current crop of Luxeon lamps is not quite as efficient as a halogen lamp run at proper voltage, but they are getting there. The 5W LS lamps are supposedly more efficient that 5W halogen lamps; I have one on order and am going to try it out as a replacement for my 5W Vistalite.

Good luck!

-Jon