An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. The battery inductry generates about US$50 billion annually worldwide and continue with 6% annual growth.There are two types of batteries: primary batteries (disposable batteries) and secondary batteries (rechargeable batteries).
Common types of disposable batteries include zinc-carbon batteries and alkaline batteries. These are most commonly used in portable devices that have low current drain, are only used intermittently, or are used well away from an alternative power source, such as in alarm and communication circuits where other electric power is only intermittently available.
The oldest form of rechargeable battery is the lead-acid battery. The lead-acid battery is very heavy for the amount of electrical energy it can supply. It also requires good ventilation to ensure safe dispersal of the hydrogen gas produced by these batteries during overcharging. However, its low manufacturing cost and its high surge current levels make its use common where a large capacity (>10Ah) is required or where the weight and ease of handling are not concerns. Car battery is one of most widely used lead-acid batteries.
Other more portable rechargeable batteries include nickel-cadmium (NiCd), nickel metal hydride (NiMH) and lithium-ion (Li-ion) cells. Li-ion has the highest energy to weight ratio and has the highest share of the dry cell rechargeable market, especially in the field of mobile devices, such as cell phones, laptop computers, and digital cameras. Meanwhile, NiMH has replaced NiCd in most applications due to its higher capacity, but NiCd remains in use in power tools, two-way radios, and medical equipments.
