You could stick em in the freezer lol! A lot of power tool batteries can be re-charged, but if not you will most likely have to get some new batteries. Power tool batteries can be found at a local hardware store or online at eReplacementParts.com - Also if your charge has gone down tremendously, you could check the warranty and see if it falls under the terms to get a new one. Good luck!
Brandon Swenson
April 2010