3 Watt LED Bike Light Experiments
June, 2008, Rev f
Michael Krabach


Synopsis of Experiments
Prototype 1 - Resistor Controlled Prototype
Prototype 2 - Triple Cree with large heat sink
Prototype 3 - Double Cree with Individual regulators
Prototype 4 - Single Cree and regulator
Prototype 5 - Single Cree and regulator
Prototype 6 - Triple Cree revised heat sink
Prototype 7 - Triple SSC in “C” Mag-lite Head
Prototype 8 - Triple Cree in “D” Mag-lite Head
Prototype 9 - Prefabricated 3 LED Mag-lite Head
Prototype 10 - Red flasher with Wide Optic Lens
Prototype 11 - Yellow flasher no Optics
Prototype 12 - Red flasher no Optics
Prototype 13 - Red flasher two LEDs
Prototype 14 - Triple Cree with 8 deg Optics
Prototype 15 - Red flasher two Cree LEDs
Prototype 16 - Red flasher two LEDs Clear Case
Prototype 17 - Auto 12 v clearance light
Light and Beam Measurements
Conclusions, Recommendations, and Further Speculations
Summary Table and Parts Sources


LED technology is changing very fast. Just a couple of years ago commercial LED bike lights were dim (too dim for anything but a slow bike path), but being hyped for their long duration, like 30 hrs. Almost all claims were completely unrealistic because they seemed to included the 'even dimmer' light from drained batteries. The lights were totally inadequate for riding at night on roads. Meanwhile riders who demanded bright and long duration lights were using halogen and high intensity discharge lights. Now the LED technology has advanced such that bright white LEDs are common. This market has been advanced by brand names including, but not limited to, Nichia, Luxeon, and more recently Cree and SSC. Concurrently electronic regulators and drivers circuits have kept up with the new LEDs allowing the new LEDs to run at full power. First 1 watt, then 3 watt, and now some at higher wattage. Each time a new generation of LEDs comes out, technology has produced more lumens per watt than the previous. Now the LED bike lights have surpassed the halogen lights and are on the verge of replacing the high intensity discharge lights. Many of the bike light manufactures are bringing out replacement products based in the new LEDs, although with a price to pay. That is, the price that you pay. Based on the following experiments, I hope to show that you can build a comparable bike light, costing a lot less. Read this forum thread to see the current prices of bike lights.

The following table shows the data (a little out of date) and projected output of Cree Xlamps back in October 2006. Current available LEDs are over 100 lm/watt. The most common available (about $4-$5 each) to hobby builders are the P4 Bin. All my prototypes use Cree P4 Flux Bin XR-E 7090 LEDs, except Prototype 4 below which has a Q5 Bin LED, the SCC ZPower P4 (U-Bin) LEDs used in Prototype 7, and Prototype 1 and 9 with an unknown brands.

This article documents my experiments building prototype bike lights to find quick and useful methods building bike lights from parts available to anyone. When looking on the Internet for ideas, I realized that many bike lights were being built from scratch and some by modification of existing flashlights. Some builders have produced excellent one of a kind lights. Some are experienced in operating lathes, milling machines and such, which produce lights that rival the commercial products, and surpassing them at times. The largest sites providing information on the construction of bike lights and flashlights are the Candle Power Forums and the Mountain Bike Forums.

The following list shows a variety of homemade designs showing the complexity of some and the simplicity of others.

The Copperhead
Machined helmet light
Double Mag-lite conversions
Machined Triple-Cree Housing
Dynamo LED Driver Circuit - PCB available
Triple DIY Bike Light
Three Watt Luxeon Bike Light
Luxeon LED Bicycle Headlight from Standard Parts
Triple Luxeon LED Bicycle Headlight from Standard Parts

The following are compiled lists of more projects.

DIY LED headlight projects & info...
Home Made Bike Light Database

My experiments strive for simple solutions with the following guidelines.

Before we go into the details of the project, let me describe the lights that were built to give the reader an idea of what the experiments produced. Then I will describe the experiments, how the lights were constructed, and my recommendations. (All the thumbnail photos are linked to larger images.)