Rechargeable Batteries
Rechargeable batteries power much of modern life. Whether its a mobile phone, a PDA, a camcorder, a cordless phone or one of the many other gadgets we take for granted, they all use rechargeable batteries.
The technology (or cell chemistry) used in rechargeable batteries gives each type of rechargeable battery unique characteristics:
NiCd Nickel Cadmium Rechargeable Batteries
Ni-Cd or NICAD rechargable batteries have been in use for a while. They are very robust, withstand high temperatures very well, and retain their charge over long periods of time. Unless fully discharged before each recharge, they develop a "memory effect", which limits their performance. The Cadmium used in their manufacture is also harmful to the environment, so NiCd rechargeable batteries are gradually being replaced by NiMH rechargeable batteries.
NiMH Nickel-Metal-Hydride Rechargeable Batteries
Ni-MH rechargeable battery technology is a big advancement over NiCd rechargable batteries. In comparison, they store more electricity in the same space, they can provide bursts of power more effectively, and they are lighter. NiMH rechargeable batteries do however lose 1% to 3% of their charge per day when not used. A NiMH rechargeable battery is also damaged by overcharging. A charger designed especially for NiMH batteries will thus provide optimal performance and life, especially if the NiMH cells are recharged just before use.
Li-Ion Lithium Ion Rechargeable Batteries
Even more recently, LiIon rechargeable batteries have emerged, especially in demanding applications such as digital cameras and camcorders. Their use of Lithium technology provides even better performance than NiMH rechargeable batteries can provide.