Probably you already know the solution: Power Banks, as mobile chargers, with which you can recharge in need all its mobile devices via a USB cable. With 6600mAh mobile charger from V7's pretty powerful and donated the power-hungry iPhones a good amount of extra power, with which one comes loose during the day. In principle, even several times.
4 small LED displays ensure the bottom of the very pretty in white held apparatus power bank that you will be always informed about the current state of the energy reserve. In addition, even a LED flashlight is built, if you need more light in the darkness to find his front door key.