I already mentioned this on another thread, but I have a Ravpower
one and I love it and can't stop recommending it. Since I'm a heavy phone user when it comes to trips, i always have this baby with me. No more dead battery before going back to the hotel. My wife usually holds onto this during our trips in her purse and when i need to charge, I can just charge it on the go. It also has 2 usb ports so both my wife and I can charge at the same time and it will give enough juice to charge both our phones at the same time.