Nickel cadmium or NiCd was the first type of portable rechargeable battery and in many ways is responsible for revolutionizing the use of electrical devices, particularly cordless power tools. Battery technology has advanced considerable since the first NiCd battery was introduced and many devices are now powered using lithium-based cells which produce increased voltage, have more endurance and, specifically, are not prone to suffering from power loss. However, if you have old NiCd batteries that you think are dead and no longer usable, consider trying to renew them. Using a process of deep discharge may revive your batteries and give you up to another year of use.
1. Place your old NiCd rechargeable batteries into your charging device. Though you may have given up charging your batteries, you might find they still can take a charge. Turn on the charger and allow it to charge your batteries until the charger’s “battery full” or similar light illuminates.
2. Remove the old NiCd batteries from the charger as soon as the charger indicates they are full. It’s important you start the deep discharge process immediately. Put the batteries in the device they power.
3. Turn on the device and set it to use as much energy as possible. If the device is a cordless power tool set it to run at its highest speed setting. If it’s an application driven device such as an iPod, cell phone or similar, open as many applications as you can. You need the device to use energy from the NiCd battery quickly.
4. Turn off the device and remove the NiCd batteries once it stops operating. The time it takes before it stops operating depends on the condition of the battery. Leave the battery to rest for 15 minutes.
5. Insert the NiCd battery into the device again and turn it on. You may find that despite the battery appearing to be dead moments earlier that it still has some energy. The deep discharging process is beginning to break down the nickel-based cell structure in the battery. The reason your NiCd isn’t retaining a charge for long is because the internal battery crystals have grown in size. Deep discharging breaks the crystals into tiny units; the smaller the crystals the more energy the battery can retain.
6. Leave the device running until it stops then repeat the process until you find the NiCd battery can’t power your device. You may need to do this three or four more times, but it’s worth doing.
7. Put your old NiCd batteries back on charge as soon as they are fully discharged, a process that can take a long time to complete. Leave the batteries charging until the charger indicates they are full. The next time you use your NiCd batteries you should find they have more power and last longer.