3 Watt LED Bike Light Experiments
June, 2008, Rev f
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 15 Red flasher two Cree LEDs

This prototype was constructed the same as Prototype 13 except I used two Cree red LEDs to increase the brightness, over the generic red LEDs. The case was the same Vistalite case but this time I tried to align the LEDs more symmetrical around the centerline. The marks are seen on the heat sink plate which since is hand cut, is not symmetrical with the red lens. The green spacer goes under the heat sink to raise the LED star bases above the battery lips. The regulator is the same as prototype 13 (DX SKU-7302) which supplies 3.7v to the two LEDs in series. The Vf of the red LEDs is rated at 1.9-2.0 volts. The DX-7302 is rated at 500 ma. I measured 165, 180, 325 ma on Lo, Med, and Hi for battery current on the steady modes. Across the LEDs (each LED drops the voltage) it is v, v, v for Lo, Med, and Hi in the steady modes. I found an old Vistalite mount that enabled me to mount this light on the seat post. The resulting beam is seen in the beam shots, which is brighter than the generic red LEDs in prototype 13. The beam pattern is sightly narrower because the LEDs are set lower on the star bases than the generic and the LED dome lens is different. This results in a beam pattern less wide and more concentrated to the rear. An excellent very bright flasher. This light is almost too bright to be riding behind but will do well if you plan to ride in traffic and not a bike path. The flashing modes are the same as prototype 13 and repeated below. This regulator remembers the last setting when turned off.

(Directions to configure modes and groups.)
(1) Low, Med, High, Fast strobe, SOS
(2) Low, Med, High
(3) Low, Med, High, Fast strobe, Police strobe, Med strobe, Slow strobe, Beacon strobe, SOS