While the functionality of smartphones become more impressive with every release, battery power is still a major issue. Most people cannot keep their phones running for more than a day, if even that long. Mophie continues to make the most interesting battery packs for phones, convincing both in terms of functionality and design. Today we present their latest release, the Mophie Power Reserve. Power Reserve is a compact, quick-charge battery with an integrated lightning cable and a convenient key ring to put it on your key chain. We love the size and functionality of the new battery pack, making it easy to have it with you at all times, without having to actually carry a full-on battery pack case. You can buy the Mophie Power Reserve for $50 in three colors here.