Over on Amazon, they are currently selling the Omaker 15,600mAh external battery pack for just $22.99. This battery pack has 2.1A USB ports. And there's two of them. So that you can charge two devices at the same time. It is a 15,600mAh battery, so it's about 5x the size of the Galaxy S5's battery pack. It's currently available for $29.99, but if you use the coupon code 11OMAKER at checkout and get $7 off. You can pick up the Omaker 15,600mAh battery pack from the link below.