How to keep charging your USB devices past your PC's bedtime

There was a time when the only device I needed to charge via my PC's USB ports was an iPod--later replaced by a smartphone. Now, I've got portable routers, an activity tracker, a mini Bluetooth speaker, and any number of other little gadgets that can suck juice straight out of my PCs USB ports. It's probably the same situation for most people these days. The only problem is that if your PC goes to sleep, your charging capability often does too. One solution is to tell your computer to never go t...