3c Cree XRE Maglite modding with a megabyte of pics to show you how.

[3rd_shift]

Yes, a 3c cell maglite that is actually worth bringing to work.
But it takes a little work to make it do this.
120+ lumens of light from regular unleaded c cell batteries in a back pocketable light with about 8+ hours of runtime.
"Ladies and Gentlemen, start your soldering irons!"
Candlepowerforums link.