Unlike single-use batteries, which must be replaced once their charge is used up, rechargeable batteries are designed for the long haul.
Depending on the application, some rechargeable batteries can recharge up to 1,000 times! Recharging the battery simply reverses the chemical reaction inside it. This changes the battery’s components nearly back to their original state and allows them to be reused.
About 80 percent of rechargeable batteries are currently composed of nickel and cadmium (known as “Ni-Cd”). Ni-Cd rechargeable batteries are commonly found in cellular and cordless telephones, video cameras, portable power tools, and laptop computers. The use of these batteries continues to grow. Small sealed lead acid batteries (SSLA) are used in emergency lighting, security and alarm systems, computer backup devices, and hospital equipment. They are also used in cellular phones, laptop computers, and power tools.
Rechargeable batteries may initially be more expensive than single use batteries, and they sometimes require the purchase of a recharger, but the upfront costs are often outweighed by the long-term cost savings and environmental benefits of rechargeables. Each rechargeable battery may substitute for hundreds of single-use batteries over its useful life.
-from www.epa.gov
