Craftsman makes a range of cordless power tools operated by different voltage batteries, depending on the type of tool. The craftsman 18-volt battery is generally fitted to the more powerful range of tools and can contain 15 nickel cadmium cells (NiCd), or 5 lithium ion (Li-ion) cells. The chemical structure of Li-ion cells calls for battery refurbishment by professional battery restorers -- as the battery pack contains energy surge breakers to ensure power doesn't fall below or increase above a certain level. However, if your 18-volt Craftsman battery contains NiCd cells, and providing the battery isn't too damaged, it can be refurbished.
Check if your 18-volt Craftsman NiCd battery can take a charge -- however small. Put it on charge until the charger indicates the battery is full, then immediately place it in the power tool and turn on the tool. If it runs, even slowly, you can probably refurbish it, but if it doesn't, its necessary to get a replacement since the damage is too great.
Set the power tool to run at its lowest power setting. You need to allow the Craftsman 18-volt battery to discharge energy slowly. Inside each new NiCd cell are thousands of very small, nickel-based crystals. However, over time, particularly if you didn't fully discharge your battery every six to 12 months, the crystals expand and weld together. This results in the cells' ability to retain energy and gradually powers your tool for shorter and shorter periods. A slow discharge breaks the cell structure and effectively refurbishes the battery.
Allow the tool to run until it completely stops. The Craftsman battery and tool are now quite hot to the touch. Let them both rest and cool. During the cooling period, the crystals start to break up.
Turn on your power tool once the Craftsman battery is cool to the touch. You'll find the cooling process has resulted in the battery regaining a little power and your tool operates. Let it run until it stops using a low-power setting. The more times you are able to repeat the process, the better the chance it gets refurbished.
Remove the Craftsman battery from the power tool once you have repeated the process as many times as possible and your battery won't power your tool. The battery is completely discharged and the crystals have broken down, so the size is similar to when you first purchased the battery.
Put your battery on charge, once the battery is totally cool. Let it charge until full. Check the side of the battery to see if it's warm. A refurbished battery takes much longer to charge and gets warm during the process. The longer it takes to charge, the better the results.
Put your Craftsman battery into the power tool. Your refurbished battery has much more energy and you find it operates your tool for much longer.