3 Watt LED Bike Light
June, 2008, Rev f
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The following table shows the data (a little out of date) and projected output of Cree Xlamps back in October 2006.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.
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.
LED headlight projects & info...
Home Made Bike Light Database
My experiments strive for simple solutions with the following guidelines.
Only hand tools such as a simple vice, hacksaws, metal files, hammers, electric drills, sandpaper, and such will be used.
The designs should be as simple as possible, portable between bikes (I have a lot of bikes.), cheap to build and bright.
The lights are not waterproof. For simplicity, since rainwater is not very conductive and I don't ride at night in the rain. Otherwise use a plastic bag and tape.
The construction material should be readily available at most hardware stores (Home Depot, Lowe, Ace) and local electronics stores (eg Radio Shack stores).
The batteries for the lights should be readily available and simple. No Li-ion batteries will be used, but the designs are compatible. If you are considering using Li-ion batteries, read this forum thread about LED drivers, If you don't know what Li-ion batteries are, stick with the ones recommended.
The LEDs, drivers and optics will have to be purchased from the Internet because they are uncommon enough that they are not available locally. All the sites allow purchasing small quantities of parts.
It is assumed that the builder is competent with shop tools and a soldering iron to the extent demonstrated in this article.
The lights will have a beam output that will equal, or exceed the beam output of much more expensive commercial bike lights such as this three beam example, or this single beam example. Of course in a year this criteria may no longer be true as the commercial brands get better LEDs.
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.)