My iPhone is stuck on 85%, why?

Okay so basically I've had my phone on charge practically all day via usb and it's charging BUT it's stuck on 85%, it was 84% before but then I switched usb ports.

I'm not sure what the issues is. Has anyone else had this problem?

Added (1). I doubt that the battery is damaged. I've only had the phone for 5 months. & I love my iPhone too much to disown it and get a Samsung 3. After havin the iPhone I doubt I'll be leavin Apple Products any time soon lol.

Power off the iPhone and unplug the usb (turn off the computer if it is a computer).

Plug everything back in and turn everything back on, wait an hour and see if it charges beyond 85%.

If it does not the battery is broken and can only charge up to 85%. You can't replace an iphone battery… Crush it with your foot and then buy a Samsung Galaxy S III with a battery that can be replaced when it dies/breaks.

I'm not sure why but when my iPhone freezes or does something a bit weird I always restart it and then it seems to be fine again. So try restarting it by holding down the home button and the power button at the same time until the screen turns black. It should either start up again by itself or just press the power button like you would to turn it on.