We’ve seen this hack a bunch of times, but this does a great job of internalize all of the phone-side inductive charging components.
It uses the Palm Pixi wireless charging hardware which seems to be the most popular system out there. We’ve already seen that you can add this to any phone that uses USB for charging. But we don’t like the idea of opening the phone to solder connections to the USB header. We also don’t want a USB plug sticking out the bottom of the phone all the time.
This hack satisfies both issues, and it’s actually thanks to the manufacturer. The Samsung Galaxy S4 just happens to have two contacts available inside the removable back plate which are designed for Samsung’s own inductive charging hardware. Contact with the Palm charging hardware is made by pressing copper foil into place. Mating foil traces on the inside of the back cover patch this into the Touchstone receiver hardware which is a direct transplant from a Palm case.
This is touted as a solution that costs under $30. That beats the current price of a genuine Samsung inductive charging kit by a wide margin.

http://hackaday.com/2013/08/12/galax...side-the-case/