NewTrent icarrier 12000 mAh external battery pack

Originally I posted a question about solar chargers, but reading more about them and the requirements for charging, I decided they would not be practical for my application which is multiday alpine backpacking trips. Afternoon thunderstorms occur almost daily and just when I would want to use the camera, ie daytime, it would need to be charging. So some more research online came up with a different solution, external 12000mah dual usb
.
I bought the charger based on reviews that claimed three to four full charges for the iPhone and a little less for the iPad. The unit was charged when I received it, I ran my phone down to 5%, which I never would do otherwise and let it charge overnight. Starting the next day the battery pack was my sole source of power for my iPhone 4s. I used it as normal, taking no extra precautions to decrease battery drain. I turned it off at night and back on the next morning. With my level of use, a handful of phone calls per day, some texting, and opportunistic photography, the battery lasted a full 6 days ! I was amazed, it charges using the iphone USB cable and charges about 20% slower than a 110 outlet. It takes a couple of hours for the unit itself to be recharged using a 110 outlet.