Mobile devices such as smartphones and tablets are powered by batteries. These are usually built into the device itself, but have a limited capacity and therefore a relatively short life between charges. A discharged phone needs to be recharged by connecting it to a mains-powered charger. However, this is not always possible. PowerBanks come to the rescue. These devices are nothing else but mobile batteries dedicated to charging mobile devices. All you need to have with you is a PowerBank and an appropriate charging cable which you plug into your phone to start charging your device.