I'm just going to say that the Arduino needs to also run when the PC is off, for just power.
Hence, I need a back-up battery.
As for a powered hub, I'm not really familiar with what it is. I looked it up... so... I still dont get it.
I would plug the micro into one of the usb slots,
then the hub to the PC USB...
and then the hub to the cell phone back up battery?