What Is a NiMH Battery?
Replacing disposable alkaline batteries in portable consumer electronics is expensive and can be harmful to the environment if not disposed properly. Nickel-Metal-Hydride (NiMH) batteries are rechargeable cells that have a wide variety of uses. NiMH batteries can be used and recharged hundreds of times, as compared to disposable alkaline batteries which can only be used once. NiMH rechargeable batteries have improved greatly since their inception in the early 1980s with increased power and faster charging.
History
NiMH batteries were first developed by Ovonic Battery, and the technology behind them is patented until 2021. Ovonic does not produce or manufacture NiMH batteries; however, they offer licenses to companies such as Energizer, Sanyo and Samsung to use their technologies. The process for creating NiMH batteries has been improved to allow higher capacity storage in the NiMH cells. Typical AA NiMH batteries from 1991 compared to 2008 had capacities of 1100mAh and 2700mAh, respectively.
Applications
NiMH batteries are very versatile. Consumer NiMH batteries are available in most sizes of disposable alkaline batteries-- AAA, AA, C, D and 9 volt. NiMH batteries are also used in more specific applications from computers, power tools and even Hybrid automobiles. Uninterruptible power supplies often use NiMH batteries for power backup due to their low cost and maintenance.
Alternatives
NiMH batteries are drop-in replacements for most alkaline batteries. Alkaline batteries can be considered an alternative to NiMH; however, they are not rechargeable. Lithium-Ion (Li-Ion) batteries are another form of rechargeable battery that has some advantages and disadvantages when compared to NiMH. Li-Ion batteries can be formed in any shape, as compared to NiMH which uses the typical cells. Li-Ion batteries have a much higher cost than NiMH, and are usually used for specific applications instead of an alkaline replacement.
Benefits
Since NiMH batteries can be reused hundreds of times, they save a great deal of money over the life of the battery. Typically, NiMH batteries are three to four times the cost of standard disposable alkaline batteries; however, since they are able to be recharged, the cost will be recovered after a few uses. NiMH batteries can store a much higher capacity than alkaline batteries. NiMH batteries will last much longer in high-power portable electronics such as digital cameras and music players. Most digital camera manufacturers recommend the use of NiMH batteries over alkaline.
Charging
In order for a NiMH battery to be reused, it must be recharged. There are many types of chargers available for NiMH batteries. Some chargers will be for a specific type of battery, while others will allow for the charging of multiple battery types. Standard chargers will charge a NiMH battery in about 12 hours. Rapid chargers are also available that can charge a NiMH battery in only a few hours.
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