Adafruit 1 Watt Cool White LED - Heatsink Mounted
Make a 1 Watt flashlight or a headlamp with this ultra-bright LED. The LED is very bright, with 90 Lumens in a 140 degree lambertian pattern. Compared to most LEDs, you would say this is 30,000 millicandela. Either way, its incredibly bright! The output is a 'cool' 6000K pure white, not a 'warm' incandescent-looking white.
The LED is mounted onto an aluminum PCB for heatsinking, and it also makes it easy to solder in. Simply connect to the big + and - pads on the PCB (there are two of each).
The best way to drive these LEDs is constant current, @ 350 mA, but you can get away with under-driving for compactness. At about 3V, the LED draws ~200 mA, so connect two Alkaline batteries up directly with no resistor for a basic bright lamp. You can also try driving it directly with a 3.3V power supply, that will probably work OK as well (although its not ideal) - that's what we did when we made a vintage LED bike light using a 1W white LED.