When I first got my Edelux II, I regretted not getting a Luxos U for the usb port. But now that I've switched to a Galaxy S6, my original choice is just as well.

While most phones take a 5V charge, the S6 takes 9V. I don't even think there's a regulator out there I can use.

I also took to turning off the light when I lock up. It's amazing how many people will really inconvenience themselves to let me know I left my light on.