Abstract: A mobile device case contains an onboard retractable charging and/or data cord, preferably a USB cable or other equivalent, which allows the user to charge on the go from an available USB port without carrying an external charging cord or transformer adapter. The mobile device case can use various optional interchangeable tops that allow the user the ability to switch tops for the case. Optional tops include a simply top to secure the device into the lower base of the case, a top that contains a supplemental battery that, by engaging a switch on the top, transfers power to the mobile device's battery, and a top which serves as a transformer adapter. The latter top contains a USB:port (or equivalent) and fold-out prongs that can be plugged into an outlet. Furthermore, an improved electrical contact system permits an electrical connection between a reel for the retractable cord and a mobile device contact pin without metal-on-metal contact while the reel is moving.