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

Contents

Introduction
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

Prototype 14 Triple Cree with 8 degree Optics

The Prototype 6 uses L2 Optics for a beam pattern that is adjustable with the sub lens diffusers. One difficulty in making that prototype is filing the L2 optic base to accommodate the LED power wires. An alternative is to use optics that do not cover the contact points on the star base. Not a lot of choices were available but item DX SKU-1920 or KAI SKU-1503 are 8 degree optics. These work well in small flashlights but I wanted to see what they would do in a bike light where spillover might make the narrow main beam adequate. The basic construction of the light is exactly as Prototype 6 with the same Luxdrive 3023 Buckpuck in the pre-wired version used with an external pot for brightness control. The snap on lens can be seen in the last photos, which are specifically designed for the Cree LEDs. The last photo shows the optics bonded to the base with urethane glue. This variety bubbles when it dries but works fine.

The prototype uses a 12 volt gel cell for power and is the same as Prototype 6 with different lens. The final prototype is shown below. The beam pattern (shown under the Light and Beam Measurements section) is quite narrow and very bright. There is spillover, but I think this beam pattern is only useful on long straight roads, not on twisting roads or paths. It does keep the light low and less offensive to oncoming cars.