Today I tired plugging in my 4S in to my car charge and it won't charge at all. I'm using a usb cigarette charge and Apple's sync cable. Anyone else run into this issue? I know my usb and sync cable work fine since I tested it out with my wifes iPhone4. Thought: Since the 4S is using the A5 (same as the ipad) does that mean I would need a 2.1amp usb charger?