Nickel-cadmium (NiCad) batteries are rechargeable, and can last for years provided you discharge and charge them properly. Problems may occur if you recharge NiCad batteries when they have only been in use for a short while. NiCad batteries contain very fine crystals that store energy. As these crystals grow, the battery has less surface area for energy storage, and the battery's capacity drops. This is known as the "memory effect"; it gives users the impression that the battery is fully charged when it's actually only halfway charged, which can result in the battery going dead after very little use. These larger crystals form more rapidly when you do not discharge the battery fully before recharging. When this happens, you need to revive your NiCad battery.
Insert your NiCad battery into your device and turn the device on. Check the battery charge display to see how much power it has.
Open as many applications on your device as you can. You need to get your device to use as much power as it can, as quickly as possible. Regularly check the battery charge display to make sure that it's depleting. Once the display indicates low power, your device should warn you that the battery needs charging. Ignore this warning.
Continue to use your device with all applications open until it turns off due to low power.
Turn your device on again. There should be some power left. Leave your device turned on, but don't open any applications. Leave the device running until it turns off automatically, and then turn it on again.
Repeat Step 4 until your device no longer turns on. This indicates that you have fully discharged your NiCad battery.
Recharge your battery at the lowest rate you can. If you have a variable rate charger, let the battery trickle charge at the lowest possible rate. If your charger is preset, let your battery charge until it is full and your device tells you to disconnect the charger. This should revive your NiCad battery.
If your NiCad battery does not retain its charge after you complete these steps, repeat them. It may take a couple of cycles to revive the battery. If your NiCad battery does not retain its charge after several attempts, replace it.
Many websites provide instructions for reviving NiCad batteries using mobile welding units to short the terminals. These techniques are potentially dangerous. It's a lot safer, and ultimately cheaper, to spend a few dollars on a new battery.