Unlike something like Xbox's Play & Charge Kit ... Then again, it's also not meant to replace the controller's internal battery, just supplement it so you can game for longer.

To check the Xbox controller battery on your PC, click on the Xbox Button on the controller to open the home screen You will see the battery level indicator at the bottom right corner. Besides it ...

Reader, [Fox9p3400], opened up an Xbox 360 controller battery pack so we could all see what goes into one. It contains two Sanyo 2100mAh NiMH AA rechargeables (Model HR-3U 1.2V). In addition to ...