Nickel cadmium (NiCad) batteries, including those made by Ryobi, are infamous for suffering from a condition known as the "memory effect" (because they appear to lose their memories). However, Ryobi NiCad batteries don't really have memories. They actually contain thousands of tiny nickel cadmium crystals that retain electrical charges. The smaller the crystals, the more charge they retain. The memory effect occurs when a Ryobi battery is not fully discharged on a regular basis and is exacerbated when it is charged too often. When this occurs, the tiny crystals grow, reducing the overall surface area and preventing the battery from taking a full charge (causing it to go dead quickly). Fortunately, as is the case for any NiCad battery, a Ryobi battery can easily be fixed.
Hook your Ryobi NiCad battery up to its charger. Let it charge until the charge indicator light goes out.
Turn off the charger and remove the Ryobi NiCad battery.
Put the Ryobi NiCad battery into the device that it powers. Turn on the device and let it run. Allow the battery to discharge energy until the device stops working. However, the Ryobi NiCad battery is not completely discharged, even when your device stops.
Wait for half an hour, and then turn on your device again. You will find that it operates, although rather slowly. Let it operate until it stops.
If the device still operates, repeat the process. The device will not operate once the Ryobi NiCad battery is fully discharged. At this stage, the crystals in the NiCad cells have been reduced in size--similar to when you first purchased it.
Put your Ryobi battery in your charger. Turn on the charger and let it charge until the charge indicator light turns off. You will find that it takes a lot longer than it did the first time. This is because the crystals have been reduced in size and can now retain more energy.
Turn off the charger and remove the Ryobi NiCad battery from the charger. Put the battery in the Ryobi tool that it powers. You will find that the battery has more power and lasts much longer.