Re-Fuel Techie 7800 External Power Bank Charger - 7800mAh 2-Port USB External Battery Power Bank | Portable Phone Charger for Samsung, iPhone, and Android Smartphones (Black Green) Power Bank comes pre-charged and ready to use right out of the box. 2.1 amps of charging power gives you a quick charge whenever you need. 2 in 1 cable design fits comfortably in your bag or jacket pocket. Will hold its charge for months until youre ready to use it. Plug it in overnight and youll be recharged and ready to go the next day.