Nickel cadmium, or NiCad, Ryobi power tool batteries are rechargeable batteries the same size and shape as regular AA batteries. NiCad batteries are a terrific invention, as you simply recharge them for an hour or so and they're ready to use again. The downside to a NiCad battery is that after a while, you find the battery doesn't last long and it needs recharging regularly. This is known as the "memory effect," which refers to when the crystals in the NiCad battery enlarge and reduce its ability to hold as much energy. As a result, the battery goes dead more quickly. Discharge your NiCad battery fully to remove the "memory effect." Put your NiCad Black & Decker cordless drill battery into your electrical equipment and turn it on. Open or run as many items on your electrical equipment as you can. You need the equipment to totally consume the battery's energy, and the more power your equipment uses the quicker the battery discharges. Run the equipment until it turns off automatically. Despite the shut off, the battery is not fully discharged. Leave it for 15 minutes and it will recover enough energy to power your equipment. Turn on your equipment again and open or run some applications. Let it operate until it turns off again. Leave the battery for 15 minutes, then repeat the procedure to find it operates again. Keep repeating the process. As you do so, the crystals in the NiCad battery are breaking down into smaller crystals. Eventually, the battery won't power the equipment. Your battery is totally discharged, and the "memory effect" has been removed. Put your discharged battery into the battery charger and let it charge until it's full. The internal crystals have reduced in size and are able to hold more energy, so you find the drill battery for Milwaukee takes longer to charge, just as it did when you purchased it. Once the battery is fully charged, remove it from the charger. Next time you use the battery, you will find it has more power and greater endurance.