The nickel-cadmium battery (commonly abbreviated NiCd or NiCad) is a type of rechargeable battery using nickel oxide hydroxide and metallic cadmium as electrodes. There are two types of NiCd batteries: sealed and vented. This article mainly deals with sealed cells.
NiCad is a type of rechargeable battery. NiCd batteries may suffer from a "memory effect" if they are discharged and recharged to the same state of charge hundreds of times. The apparent symptom is that the battery "remembers" the point in its charge cycle where recharging began and during subsequent use suffers a sudden drop in voltage at that point, as if the battery had been discharged. The capacity of the battery is not actually reduced substantially. Some electronics designed to be powered by NiCds are able to withstand this reduced voltage long enough for the voltage to return to normal. However, if the device is unable to operate through this period of decreased voltage, it will be unable to get enough energy out of the battery, and for all practical purposes, the battery appears "dead" earlier than normal.
An effect with similar symptoms to the memory effect is the so-called voltage depression or lazy battery effect. (Some people use this term as a synonym for "memory effect".) This results from repeated overcharging; the symptom is that the battery appears to be fully charged but discharges quickly after only a brief period of operation. Larger cells may benefit from refilling with distilled water, or a complete electrolyte replacement. In rare cases, much of the lost capacity can be recovered by a few deep-discharge cycles, a function often provided by automatic NiCd battery chargers. However, this process may reduce the shelf life of the battery. If treated well, a NiCd battery can last for 1000 cycles or more before its capacity drops below half its original capacity.
Manufacturers typically supply instructions for safe handling, use, and disposal of nickel-cadmium batteries. These warn against physically damaging the cells, short-circuiting when fully charged, and overcharging.
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- ↑ Dan's Quick Guide to Memory Effect
- ↑ For example, Rayovac Safety Data Sheet Rayovac Safety Data Sheet
- Bergstrom, Sven. "Nickel-Cadmium Batteries – Pocket Type". Journal of the Electrochemical Society, September 1952. 1952 The Electrochemical Society.
- Ellis, G. B., Mandel, H., and Linden, D. "Sintered Plate Nickel-Cadmium Batteries". Journal of the Electrochemical Society, September 1952. 1952 The Electrochemical Society.