Phone Charging Idea

I saw this at a local business. It's some kind of buseinss that provides service for vehicles and they arranged it where you can use one of their display batteries to charge your phone while stuck in their waiting room.

I have no idea how to do this, so I cannot provide instructions, but if you can figure out how to replicate this, you could use this to let people charge their phone at the table at a free meal site so they can keep their eye on their phone.

You could also use this idea to provide phone charging service if you happened to set up a one-a-week meal at a park or something where you don't have electric service.