Build a 400 lumen bike light in an Altoid tin for ~$50. The new incredibly bright, high efficiency LEDs by Cree, the Cree XR-E are simple to wire and are relatively cheap. Drawing very little power but able to output 100 lumen each at 350 milliamps and an incredible 200+ lumens each at 1000 milliamps these little LEDs are at least 30% brighter than last years best Luxeon LEDs. Power for 2 or more hours with 4 AA NiMH rechargeable batteries. Everything tucks neatly into an Altoids tin. Ride bright and never fear the dark again.
- 2 x Cree XR-R Star LED (LEDSupply.com 2 x $8.49)
- 1 x 3023-D-100 Wired BuckPuck, 1000mA Output (LEDSupply.com $19.99)
- 1 Altoid Tin
- 1Minoura Mounting Bracket (for water bottle cages) (Nashbar.com $3.50)
- 1 Plastic 4 x AA battery holder (Radio Shack $1.50)
- 4 x AA rechargeable NiMH Batteries (multiple sources ~$7)
- Cree L2 6 degree optical lens (LEDSupply.com 2 x $2.00)
(others - solder, solder iron, 5/64 drill bit, drill, artic silver epoxy (preferred), LEDSupply.com )
Step 1: Drill 4 holes in your Altoid tin
Drill 2 holes in the bottom of the tin to mount the bracket which will hold the tin to your handle bars.
Drill 1 hole on each side, 1 for the wires to the LEDs and one hole to mount the dimmer switch which will control the LEDs.
Step 2: Assemble the internal components
Bolt the mounting bracket to the bottom of the tin.
Insert a 4 x AA battery holder.
Insert the Buckpuck dimmer switch and bolt in place.
(The BuckPuck is the postage stamp size block in the picture. It accepts power from 5 to 32 volts and outputs the constant current high power LEDs like. The dimmer is a potentiometer switch which controls the brightness of the LEDs and comes prewired with the 3023-D-E 1000P Wired BuckPuck.)
Step 3: Parallel vs Series connection of the Star LEDs
Use the parallel connection for 4 batteries (6 volts). For higher voltage battery packs I recommend the series connection.
Step 4: Solder the BuckPuck and LEDs in Parallel
The Cree XR-E Star LEDs have very wide solder tabs, clearly labeled + and -. For the battery pack shown (less than 6 volts input into the buckpuck) wire the LEDS in parallel. If you have a higher voltage input you can wire the LEDS in series as shown below.
Step 5: Epoxy LEDs to Altoid Tin
Solder wires from 4 AA battery holder to Buck puck wire.
Apply epoxy to the back of the soldered LEDs and hold in place until solid. Arctic silver thermal epoxy is probably best as the Altoid box will act as a heat sink, but I have also used standard household repair epoxy and not experienced overheating with the Cree LEDs.
Step 6: Epoxy Optical Lens, Insert Batteries and Power-on
Epoxy plastic optical lens over LEDS. Try not to get epoxy on the LED lenses. Hold in place until firm.
Insert 4 rechargeable NiMH AA batteries.
Turn the Dimmer Switch to on and mount on bike. Enjoy the night.