Nickel cadmium (NiCad) battery packs are increasingly being replaced by lithium ion or lithium polymer batteries. The main reason is both lithium ion and lithium polymer batteries' cells produce three times more voltage and milliamp hours than a NiCad battery cell. Lithium-based cells also don’t suffer from “memory effect” -- when you find that even though you have just charged your NiCad battery, it goes dead really fast. This is because tiny crystals in the cells have grown, resulting in an inability to retain energy. You can’t replace your NiCad pack with a lithium pack, however, you likely can fix your existing pack, saving you money versus getting a NiCad replacement.
Charge your NiCad battery pack. Connect it to the device it powers after the pack is fully charged.
Turn on your device and let it operate until it stops. Fixing your NiCad battery pack requires you to completely discharge the battery.
Remove the NiCad battery from the device once it’s stopped operating. Leave the battery to rest for about 15 minutes. During this time it regains some energy.
Replace the NiCad battery into the device it powers and turn it on. The device operates and continues to do so for a while, although you notice it has a lack of energy. Leave it until it stops.
Repeat the process by removing the battery, leaving it to rest and then replacing it in the device and turning it on. After several more times you eventually find the device does not operate. The NiCad battery is now completely discharged. The process of slowly fully discharging the battery makes the crystals in the cells break down into much smaller crystals. The smaller the crystals, the more charge the NiCad battery can retain.
Let the battery rest and cool: it takes about half an hour or so. Put the NiCad battery on the charger. Let it charge fully. You find it takes a lot longer to charge than before. The longer it takes to charge, the better -- this means it is able to hold more energy.
Remove the NiCad battery from the charger once charged. It is important that you do this, as leaving the battery in the charger can increase the chances of the memory effect returning. Always discharge your battery fully before recharging, if possible. If this is not convenient, then fully discharge it every six months using the steps above.