Determine the voltage your Black and Decker tools require. Most Black and Decker tools attach to their battery at the bottom. These batteries display the voltage with black letters. If you have lost the tool's battery, check the user's manual or check the Black and Decker website.
Remove the Black and Decker tool's original battery, if necessary.
Locate the Dewalt battery of the appropriate voltage. Any battery that matches in voltage should work with tools because both Dewalt and Black and Decker use lithium-ion batteries.
Plug the Dewalt battery into the tool. Align the knob of the battery with the hole of the tool. Push the battery into the bottom of the tool.
Press the power button to turn the tool on.