A 3W Luxeon Bike Light

At the 2004 Great Southern Randonee, I saw a really cool light on one of the other riders bikes, using a 3W Luxeon white LED, with collimator, mounted in a piece of aluminium tubing, and powered by a set of three C cells in series.

I was greatly impressed, and went about copying this light, using some of the parts from my own Audax lighting setup, namely my lithium ion battery pack and the bar mount from my old 5W Vistalite halogen light head.

In order to provide maximum flexibility in powering the light, I used a Luxdrive buckpuck luxeon driver, which operates off any voltage from about 5V up to 30V or so, and provides a regulated 700mA to the LED. This way I am able to use the light either with my Lithium Ion pack (nominally 7.4V) or else a Vistalite NiMH pack (nominally 6V).

The light is housed in a case turned from aluminium. The electronics are all mounted on an aluminium disc, that transfers heat from the LED to the casing. Shown in the above photo is the payload, with Fraen narrow lens at the left, followed by the 3W white Luxeon (Lambertian), the heatsink block, then the Luxdrive LED driver, a power switch and battery connector, and finally a second aluminium disc to cap it off.

Here's all the parts. Inside the aluminium case tube is a sheet of acrylic and O-ring. The bar mount from my Vistalite serves to hold the whole thing together.

And finally here's a couple of photos of the whole thing assembled, and attached to my handlebars.

A crappy Autocad 2000 drawing of the light can be found here. The same thing is here as a pdf.

For reference, the Luxeon, lens, and Buckpuck came from Luxeon Star. The miscellaneous electronics were just from the local Jaycar.

In use, it's about as bright as my old 5W halogen, with a similar beam shape, but uses half the power. My 3Ah 6V NiMH pack lasts a little under 6 hours, whilst my 8.9Ah 7.4V lithium ion pack should last for around 20 hours (not tested as yet). In addition, it has a low beam setting (1.5W) which effectively doubles the run-time. One of the neat things about LEDs is that if you under-drive them, they are more efficient, unlike halogens where the efficiency drops when under-driven.