We've recently seen a number of backup battery packs with wall prongs built in, eliminating the need for a separate USB cable or power adapter. Zagg is among the companies jumping on board with its Zaggsparq 6000 ($100). With its dual USB ports, the black and silver plastic brick can be used to charge two devices off the wall, or provide power to the devices when on the go. Because the two ports share 2.1A of power output, though, this unit is only…
