Originally Posted by
Super-Man
You guys know that you're not charging anything, right?
The bar is just an estimation of how much battery power you've got left before it dies out.
When you take all this load off of your iPod and put it on hold while just playing a song (opposed using the internet/playing a game), and the lit screen turns off, your estimated battery life has just increased, thus the bar fills up more, but only temporarily. Once you start to put your iPod to use again, the bar will slowly go back to how it's supposed to be.