Reconditioning your dead Dewalt rechargeable tools is time-consuming, but well worth the effort. Within each Dewalt battery pack, a series of AA or C rechargeable batteries are linked together to create a larger rechargeable power source. Replacing the smaller batteries within the Dewalt battery pack is much less expensive than replacing the entire Dewalt battery pack.
Unscrew the small Phillips screws on the case and set them aside for later. Open the Dewalt case to reveal the batteries.
Copy down the connection pattern between the battery cells before you disassemble the entire battery pack. It is important to be precise so you achieve the correct polarity when reassembling the battery.
Use a soldering iron to remove the old cells from the leads attaching them together.
Purchase new rechargeable batteries at a local electronics or hardware store that match the old Dewalt batteries within the battery pack. Match both the size and type of batteries. Size C nickel cadmium (nicad) batteries should be substituted for new size C nicads.
Arrange the new batteries in the same pattern as the old Dewalt tool battery pack pattern.
Resolder the leads onto the new rechargeable batteries.
Replace the batteries back into the battery pack and screw the Dewalt case together.
Place the battery pack on the battery charger for a few hours and the Dewalt battery pack should be as good as new.