Being a blogger and a mom who loves taking pics and videos and posting them my iphone battery is always dead. I was able to try out Power Theory® Credit Card-Sized 2500mAh Portable Charger External Battery Pack with built-in USB & Apple® Lightning Cable.
With the PowerCard you always have reserve power available, in your wallet, pocket or bag. The 2500mAh premium battery is big enough to charge your phone. It has been engineered with a new "S-Power" chip for intelligent charging and extra safety protection.It turns off automatically and charging is easy. Just plug in the Micro-USB or Lightning adapter to your phone and you will see the LED light turn red as it rescues your phone from battery death.
This is enough for 1 full charge I let me phone get down to 5% and plugged it in. It is not a quick charger but I was able to work out at the gym and listen to music while i worked out while it was charging.