NiMH battery pack

Batteries are usually classified as primary batteries that can be used only once and then disposed of, and secondary batteries that can be recharged and used repeatedly. Primary batteries include manganese batteries, alkaline batteries, mercury batteries, and silver oxide batteries. Secondary batteries include lead-acid storage batteries, nickel-metal hydride (NiMH) batteries, sealed nickel-cadmium batteries, lithium metal batteries, lithium ion batteries, lithium polymer batteries, and lithium-sulfur batteries. Recently, pursuant to reductions in size and weight of portable electronic equipment, there has been a need for developing batteries for such portable equipment with high energy density and high power density. As a variety of portable electronic devices have been developed, the development of batteries for supplying drive power to the devices has been increasingly valued as a critical one of key devices. Among other things, compact rechargeable batteries such as nickel-metal hydride rechargeable batteries and lithium rechargeable batteries have been developed and increasingly grown in demand. Rechargeable batteries are found in many different types of devices. Cellular phones, laptop computers, digital cameras, camcorders, and many other types of devices include such batteries. Types of rechargeable battery packs in common use today include lead-acid, nickel-cadmium (NiCd), nickel-metal hydride (NiMH) and the increasingly more-common lithium ion type batteries. Each of these battery types is generally characterized by a multiplicity of individual cells, each containing the basic electrode/electrolyte combination that produces a discrete voltage potential thereacross. The opposing electrodes of a given number of cells are connected together in series so that the additive effects of the individual cell potentials are combined to produce the overall desired voltage potential for the battery pack.

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