LED Headlight

I have used a 10W Vistalite headlight on my bike for since the mid nineties. The bulb finally burned out after many years of use. I figured buying a replacement bulb and screwing it in would be easy. I was wrong. My searching did not yield a direct replacement anywhere in North America. I finally gave up and decided that maybe it was time for a new system. I found a great light from BLT (a Canadian company) which suited my requirements; the Enduro Ray NH-420, consisting of a 4W LED light source, and a good Nickel-Metal Hydride battery yielding a 15 houre burn time. I though great! Technology has yielded a much better system than I have been using... time to upgrade. I went down to the local bike shop with a couple hundred dollars and found the system. It was on sale... only $500. Suggested retail $650! I could not believe that someone could charge that much for an LED, a charger, a battery, and some molded plastic parts. In fact I was insulted, and left the shop in disgust.

A quick internet search for high powered LEDs yielded the LED that I believe is the heart of the BLT system: A Luxeon-III side emitter. I found a Canadian supplier of these for $10.39. I bought a couple, one with a side emitting pattern, and one with a lambertian (90 degree cone). I also bought a LuxDrive LED driver for $23.75 and a wiring harness for $5.93. This is basically a small brick which takes any input voltage and converts it to an adjustable constant current drive. A bit of experimentation showed that the side emitting LED provided the best beam pattern and then a little bit of mechanical work got everything to fit within the Vistalite. The beauty of the system is that I am no longer constrained to 6V batteries. When my current battery dies, I can replace it with basically anything, because the driver circuit will accept any input voltage. I can easily wire in a dimmer circuit to the control module, allowing for high and low beams, but at this time just have it fixed at slightly less than full capacity, driving the LED with about 3W of power.

Anyway here is the story of converting my Vistalite to an LED light with equivalent output of the BLT system for a total material cost of $40.07.

Some links: March 2006 update: After about five hours of use, the first LED suffered a meltdown. I installed a new LED and dialed the drive current down from about 900mA to 700mA. Slightly less bright, but I have been riding this setup all winter without any problems.

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The side emitting Luxeon-III. Part Number: LXHL-FW3C. I bought the Star configuration which is simply the LED pre mounted on a aluminum board, which acts as both a heat sink, and a convienient mount for soldering wires to. This is the LED which ended up in the system, as the side emitting pattern focuses into a nice beam when placed inside the reflector.


This is the lambertian Luxeon-III. Part Number: LXHL-LW3C. The output of this is a nearly perfect uniform cone of light. This creates a great flood pattern, but does not focus at all, as none of the light strikes the reflector. I think that the ideal bike light would be one of these coupled with the side emitter to create a flood plus a focused spot... but that is a project for another day.


Here is the control module. Part Number: 3021-D-E-1000. Also shown is the wiring harness. Part number: 3021HEP. While the wiring harness is not necessary, it saves a lot of soldering. It comes with a potentiometer on the control pin so you can adjust the output current. I just set it slightly less than full and left it.


Testing everything on the lab bench. These LEDs are bright!


Here is the Vistalite. I needed to mount the LED in there.


Fortunately, my friend Matt has a metal lathe, and turned a piece of aluminum for me to fit where the bulb used to go. This cost me a beer which was not accounted for in the total material cost.






The aluminum slug sized to fit.


Thomas and Binky found the action somewhat entertaining.


I connected the slug to the LED board with epoxy. The slug acts as both a mount and extra heat sinking.




Intalled inside the Vistalite. I drilled a couple small holes through the reflector to get the wires out to the board. The slug fits with some friction, and combined with the stiffness of the wires, does not move, yet I can remove it later if necessary.


Testing everything in place.


A capacitor was placed in the supply lines. The LuxDrive data sheet suggested this for supply wires greater than 18 inches. I assume it is for noise reduction.


All the bits fit in the AA battery compartment of the housing. To get the driver brick in, I cut a slot through the battery holder to make room for the wiring.




On the bike after a test ride out in the snow


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