Make a li-po battery charging pack for your Xbox 360 controller.
A long time ago, hack a day did a breakdown on the rechargeable battery that you could buy for the xbox 360 controller. There really wasn’t a whole lot inside as a lot of your circuit for charging is actually in the charge cable. The only thing that was in the Xbox rechargeable battery is 2 Ni-Mh batteries rated at around 2100mAh, a thermal sensor, and a circuit board which has a little eeprom chip that simply informed the Xbox what kind of battery was installed into it.
In the spirit of the original hack posted by them. We will focus on working with replacing the battery cels in the Ni-Mh charger versus mutilating our Xbox controller. Dead battery packs are very easy to find and often super cheap as people just want to get rid of them.