Craftsman battery chargers seldom go wrong. Battery chargers are simply a form of transformer that converts 120 volts alternating current into a low voltage, low ampere direct current, suitable for charging a battery pack. Craftsman 19.2 volt battery chargers are sealed units and must not be forced open. However, they are fitted with a fuse which occasionally may blow. If you find your Craftsman battery charger isn't charging your 19.2 volt battery, fix it by replacing the fuse.
Ensure your Craftsman 19.2 volt battery charger is disconnected from the mains electricity supply. Locate the fuse cover. It's usually on the underside of the charger where the pins that go into the plug socket are placed. Sometimes it's on the front.
Remove the fuse cover from the Craftsman charger. If it's screwed in place use a suitably-sized screwdriver and remove the screw then lift the cover from the charger using your fingers or a flathead screwdriver. If it clips in place pry the cover off using a small flathead screwdriver.
Remove the fuse from the fuse holder. You may be able to remove it using your fingers, but use a small flathead screwdriver if it proves difficult.
Purchase a replacement fuse from an electrical or hardware store. Take the old one along as you must get an exact replacement.
Put a replacement fuse into the fuse holder and push down until it clicks in place. Replace the fuse cover: either push it into place using your fingers, or replace the screw into the screw hole and tighten using a screwdriver.
Plug the charger into the electricity supply and connect the battery you need to charge. You will find that most times your charger is now fixed.