Right now, Amazon has a pretty awesome deal on a Jackery Premium Portable power pack. This is a 12,000mAh battery pack and is only $31.95. It's typically around $129.95. So it's a really good deal. Ultra high-capacity portable charger with dual USB port with 12000mAh rechargeable battery power capacity. Super-fast charge output (5V/3A) though dual USB ports (5V/2.1A and 5V/1A) allow for simultaneous charging of your iPad, iPhone, Android, and more at high speed. This power pack and external battery charger adds 500% - 600% extra battery life.
Jackery® Giant+ Premium Portable Charger Aluminum 12000mAh Power Pack and External Battery Bank with Dual USB Port for Apple iPhone 5S, 5C, 5, 4S, iPad, Air, Mini, Samsung Galaxy S4, S3, Note, Nexus, LG, HTC. Portable Battery Charger, iPad Charger, Portable Phone Charger, USB Battery Pack, Dual USB Car Charger, Power Bank, Portable Battery (Silver)