I find myself using a USB cord to connect my phone to my 2011 Ford Fiesta to play music, but it also charges the phone. Being the paranoid person I am, I'm worried I'll drain my phone that way but I only use it because I haven't figured out how to play my music via SYNC's bluetooth. So I was wondering, if I could figure out how to use SYNC, which one is better on the car battery, bluetooth or USB that charges?