How Do Rechargeable Batteries Work?
The batteries that we use today can be classified into two types, Primary cells and Secondary cells. Primary cells are disposable batteries, like alkaline batteries. Secondary cells are rechargeables, like NiCd or NiMH. Let us concentrate on the Secondary Cells.
Rechargeable batteries work by fully restoring its energy capacity when an electric current is applied to them. They are considered to be electrochemical cells which produce a finite amount of energy, which once depleated can be recharged by reversing the chemical reaction with the aid of a charging current supplied by the battery charger.
Here are some of the more common chemistries used in rechargeables today:
NiMH - Nickel Metal Hydride
Li-ion – Lithium Ion
Ni-Cd – Nickel Cadmium
Li-ion polymer – Lithium ion polymer
Lead-acid – Combination of lead and Sulfuric Acid
Each technology has its own advantages. These may include: high power delivery for shorter periods of time, longer battery life for low power applications, quicker recharge rates, longer life times or smaller size for the same amount of energy. The designer should pick the most appropriate technology for the application.