this should tell you what you have. It's coming around time that the 4th Gen iPod begin to break, so don't be worried that you have treated it badly. Battery replacements vary from $20 to $80 here (Australia), depending on quality. I got my 3rd Gen battery replacement for $50, and when the hard drive died, i chucked it in my dad's 3rd Gen. Still pumps out 12 hrs of battery, much longer than what it was doing before the replacement.