Hello everybody! :)
Today I gonna show you an interesting project - retro bicycle self cooling 3W power Led headlight!

Last season, my old lamp headlight had bad durability, non-energy saver and bad brightness :(
This season I have made a new one - here's an intructuble to my Led headlight

Step 1:

You'll need:

2-3 Lithium-ion rechargeable batteries (standart 18650 - 3.7-4.1 Volts 2000-2350 mAh)
One 3W Led driver. (Input = 8 -12V DC Output = 3 - 13.5v DC, 700mA)
One White Lumiled Luxeon Star 3W LED.
One lens for the Led with 8 or 12 degrees
old CPU heatsink (around 6cm x 4cm x 3cm) and 1.2 inch cooler (0.03A or something about that)
1 large toggle switch (two or three positions)
Some silicone or epoxy
thermal compound (also known as thermal grease or heatsink compound)
plastic or fiberglass for heatsink mount
old headlight for bicycle
Coffee tin can with onenind top for batteries and switches
some coaxial wires (2, 3, or even 4 small wires inside from PC)

Because I had used more complicated system for headlights and rear side + stop lights you might misunderstand some steps
It will be enough 2 Li-ion batteries ad single-position toggle switch...
Also you may use another Led driver - TR-0021B inpulse led driver 4 - 18V with direct drive

As a battery charger, I've used an old RC helicopter Li-Po charger (3.9-4.1V 900mA) EK2-0851 - E-SKY Balance Charger with Mains Adaptor 7.4v/11.1v with Auto cut-off with LED indicator

Step 2:

Place the Led and the heatsink together using the thermal compound, then put the lens on the led.
As a holder you may use a plastic hairspray cup and cut the small hole in it. Put the Led with the heatsink and the lens into the cup and screw 3 small screws (sorry for my English, I'm Ukranian guy :) )

Using glue - take the Led driver stick to the heatsink) Also stick the heatsink to the plastic cup

test it all together witn the right polarity with led driver
It is quite simple scheme - you should find polarity indicators on the Led and the Led driver

The overall durability is about 100 000 hours - almost forever! (thanks to the 700mAh Led Driver, which gives stabilized voltage in 3.8V. The batteries gives 7.6-8.2V.)
Total cost is about 25$ without the battery charger!

Step 3:

If you are living in the hot climate, you may connect a small PC cooler to the heatsink of the Led.
Because our climate is hot in summer the cooler is the beat way to increase the led efficiency and durability. It also saves the led from overheating - without cooled the temp on the heatsink is about 40-50 degrees C
With the cooler - 25-35 C

It is connected between the led driver and 3W Led

Read the notes to the photo

Step 4:

Completed!
I've hide the wirings inside the bicycle frame (previvous step on snow)

This scheme is very durable!!!
I've been using it since march 2011.
Now it is November - still working as it should be!

Batteries - use E-Sky RC helicopter automatic cut-out chargers
Scheme of connections