I have a new 2013 2.5i, picked it up yesterday and love it. It is nice to have things like bluetooth and all that, but they really can drain up a phone batter quickly if used a lot. I thought "great! I can plug and play via usb and charge at the same time!" but it does not seem to work that way, does not charge at all on my iPhone. Will the usb connected charge any devices? Or its strictly only for playing files through?