Black & Decker is one of the leading manufacturers of power tools. The company makes a wide variety of handheld tools, including power drills and electric screwdrivers, as well as items used for gardening tasks. Each Black & Decker power tool uses one of three types of batteries: lithium ion, sealed lead acid or nickel cadmium. An 18V battery is one of the nickel cadmium batteries. Lithium ion batteries are lighter and smaller than the 18V batteries and can hold a charge longer. Before you replace the battery, determine if your tool will still work.
Remove the existing battery from your power tool. Look at the inside of the tool and find the model number. The model number consists of three letters followed by a series of numbers. You can typically find the model number on the inside of the tool or along one of the sides.
Read the amount of voltage on the battery. The battery itself has a small label with the voltage listed. In most Black & Decker tools, the battery comes out for fast recharging. If you have an 18V battery, you should see the designation listed on the label.
Compare your existing 18V battery to the lithium ion batteries available from Black & Decker. The company makes several lithium ion batteries that fit the different power tools that come with that type of battery. Your battery might look like a large block, a wide tube or have a raised tube attached to a block base. The new lithium battery must be the same size and shape as your current 18V battery.
Purchase a lithium ion battery that works with your power tool. When you find a new battery, it should state on the packaging or the included paperwork which tools the battery works with. Only use a battery designed for your tool.
Charge the new battery on its included charger, as it won't have a charge when it comes out of the package. Slide the new battery into the base of your power tool until you hear a soft clicking sound, which indicates that it's in the proper position for use.