this will be the BEST instructable for you.
Step 1: Parts List
* 1W white led
* 1.8 ohm resistor
* single cell lithium ion battery
Step 2: Connection
Don't forget to attach suitable heatsink, because led going to get very hot.
Othrwise led get burn out or it's life get reduced.
Led delivers around 300mA current.As I am using 1500mA battery, It will last upto 5Hrs.
Here I am using lithium ion battery from my old device.
Which have inbuilt protection circuit in order to protect the battery from short circuit,overcharging and discharging.
If you have another one,
you must required protection circuit to.