Rechargeable batteries, batteries that can be recharged and used over and over, are a modern marvel of electronic power. With millions of battery-powered cameras, computers, personal media players and other electronics in circulation, the demand for batteries grows continually higher. While early rechargeable batteries quickly discharged and became cumbersome to use, modern nickel-metal hydride (NiMH) batteries exemplify a dramatic improvement in battery technology.
Environmental Benefits
As technology has enabled progressively smaller personal electronics, devices have become increasingly smaller and more reliant on battery technology. With millions (if not billions) of personal electronics in use today, tremendous volumes of batteries are discharged and discarded every day. When NiMH batteries completely discharge, they can simply be charged back up and used again; this reuse of battery resources removes some of the burden of landfills, as millions of slowly decomposing batteries can quickly overwhelm garbage collection services. As a secondary effect, reusing batteries reduces the need for trips to the store to purchase replacement batteries, helping clear the air of vehicle emissions.
Low Discharge Rate
Users of personal electronic devices quickly realize that batteries must be replaced with some measure of frequency because they quickly expire. Because of their design, NiMH batteries are often rated at 1850 mAh or higher, enabling them to outlast their standard alkaline counterparts. In addition, NiMH batteries may retain their charge for considerably longer times than even alkaline batteries, giving them a longer "shelf life" between uses.
Size and Weight
While some batteries are bulky and others are unexpectedly heavy, NiMH batteries pack a significant electrical punch in a compact, lightweight package. The size and weight of NiMH batteries make them ideal for personal electronics, and allow the batteries to be packaged in a variety of forms to power a broad spectrum of electronic devices. Some devices, such as the Apple Macbook Air, use NiMH technology to restrict the weight of an entire notebook computer---including the battery---to under three pounds. As technology develops, rechargeable NiMH batteries may become even more lightweight, making more devices portable.
Types
Nickel-Metal Hydride technology allows NiMH batteries to be packed into a broad spectrum of shapes and sizes. Common applications of NiMH require batteries in AAA and AA form, though larger rechargeable batteries such as C and D sizes are also available. NiMH technology can also be found in tiny watch and hearing aid batteries, battery packs for specialized electronic devices and proprietary internal batteries like the ones found in Apple iPod personal media players. Cellular and home cordless telephones use NiMH batteries, as well as laptop computers and other portable devices. The technology has also been explored for use in electric vehicles like the Chevy Volt, though the success of large-scale battery deployment has not yet been established.
Warning
Although NiMH batteries are far more environmentally friendly than their alkaline counterparts, they do eventually expire and must be discarded. To minimize environmental impact, some companies offer recycling of NiMH batteries. Taking advantage of this program keeps the batteries out of landfills entirely. When NiMH batteries are discarded, they should not be burned, prodded or punctured as doing so may cause a rapid, explosive discharge of any remaining electrical capacity. In addition, users of NiMH batteries should use caution to recharge the batteries only in approved chargers, and to never use commercially available batteries in unintended applications.
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