It does sound like your battery is ready to be replaced. Follow [guide|3603|this guide] to show you how to get to the battery. It is a bit of a PITA due to the size of the Nano. Of course, before you take it apart, you could also give [http://www.youtube.com/watch?v=vG7RoC5Trqs|this a try.] the battery is available [http://www.ipodbatterydepot.com/shopping/productdetails.asp?category1=&recordid=5601|at places like this.] I hope this helps, good luck.