Hi Applecrisp.
Does the battery indicater only show a partial charge, not full, after you charge it long enough to where it says "Charged"?
If that's the case, sounds like the battery is going. My son's Mini did the exact same thing about 6 months after he got it. Here is a link to troubleshooting battery issues:
http://docs.info.apple.com/article.html?artnum=60941
If the battery needs replacing, here is a link to the iPod Service Request page:
http://depot.info.apple.com/ipod/
Hope that helps. Best of luck.