Originally published at: http://www.howtogeek.com/165093/does-my-computer-use-more-electricity-when-charging-usb-devices/
Your computer consumes a large amount of power just idling there awaiting your command, does charging a smartphone or tablet off one of the USB ports impose much of a demand on it?
Would this be the same if you plug in your cell phone to your Xbox? Does the Xbox pull extra power when I plug my cellphone in the usb ports?
Absolutely! Charing your phones will consume power.