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

Prototype 17 Automotive 12 v Clearance Light

While this is more of an adaptation than a prototype, I am placing it in the sequence of prototypes. I was trying to determine the best combination of lights for night time commuting and did not want to limit the rider to changing AA rechargeable batteries every few days. I also found after looking at all the flasher lights that the police (warning flasher) mode seems the most effective for the biker. Whether it is illegal in any jurisdictions, was not the point, what was important was a car driver to notice the light and not be mesmerized by the strong flashing mode. While commercial flashers have a constant flashing mode, these prototype flashers were just so much stronger that they are somewhat annoying in the constant flashing mode. Slow flash is OK but, I liked the warning sequence much better. To keep the rider always visible (between the flashing sequences) I decided that a steady tail light was necessary. Since any commuting was going to be done with a 3 Cree (or SSC) light on the front, 12 volts was already available and could be used for the tail light. That way the rider only had to keep one battery recharged.

I did not want to go through the trouble of converting 12 volts down to the LED range so I used a Walmart red double clearance light (part no. V168R) from the automotive section. The one found was perfect size and had two screw holes for attaching the light to the bike rack. The LED unit is wired directly back to a plug, to plug into the 12 v gel cell. No switch is necessary. The assembly draws only 47ma so it does not affect the run time of the gel cell which is supplying up to 1 amp to the front light. The photos show the tail light attached to the bike rack with tie wraps and urethane glue so it does not twist up or down. The light is very bright and matches with the generic red LEDs in prototype 16.