Most small electronic items include USB chargers today. Which means they may have to get charged off from another device, such as a laptop or desktop computer, that has a USB port. Even though USB charging has grown to be pretty pervasive, it could also be inconvenient. However, power bank chargers provide a fast, less complicated, and also safer solution.
http://www.youtube.com/watch?v=lm3_B3efcVE
https://vimeo.com/126684850
