Mophie, a leading maker of battery accessories for mobile devices has just announced the Mophie Juice Pack for the Galaxy S4.  Consisting of a slick form fitting case with internal battery, the Juice Pack promises up to 80% more power for the S4 as well as superior protection.  Offering up a 2,300 mAh battery, the Mophie case promises up to 13 hours of additional talk time, up to 6 hours more of internet use, 35 hours of audio playback or 7 hours of video.  A pass-through microUSB cable lets you charge your S4 without removing the case.  Alternately you can also choose to charge both your phone and the battery case simultaneously.  The Mophie Juice Pack for Galaxy S4 runs only $99 and is available at leading retailers.