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Title: NiCad, Lithium, and NiMH Batteries Word Count: 502 Summary: Three main types of rechargeable ba tteries are used in newer technolog y hand held devices. Scientists are constantly trying to develop batte ries with better technologies that make them faster, more powerful, an d more lightweight. Keywords: nicad batteries, nimh batteries, li thium batteries, li-ion, nickle cad mium, nickel metal hydride Article Body: Three main types of rechargeable ba tteries are used in newer technolog y hand held devices. Scientists are constantly trying to develop batte ries with better technologies that make them faster, more powerful, an d more lightweight. In the past, th e only type of rechargeable battery available was a lead-acid battery, which contains liquid and must be kept ventilated in an upright posit ion. Though still used in autos and motorcycles, scientists have devel oped gel-batteries, where the liqui d is semi-solid and will not spill. These batteries, most commonly use d in new had held devices are nicke l-cadmium (NiCad), nickel metal-hyd ride (NiMH), and the newest, Lithiu m Ion (Li-Ion) batteries. Nickel Cadmium, or NiCad batteries are the least expensive of the thre e types, because it has the least p ower. They are primarily used in po rtable phones, power tools, and ot her hand held devices. They are mor e practical than lead-acid batterie s because of their increased power and light weight. They also have an advantage over alkaline batteries which are not usually rechargeable. NiCad are said to be the number on e sufferer of the “memory effect” w hich in fact is really a lazy batte ry effect, where the battery discha rges quickly after being fully char ged. A NiCad battery only lasts 100 0 full cycles, so eventually they n eed to be replaced. NiMh batteries are next of the podi um for newer, more powerful batteri es. Though similar to the NiCad bat teries, NiMh batteries do not conta in toxic cadmium, so they are consi dered more of an environmentally-fr iendly battery. They are also highe r capacity than NiCad and are said not to suffer from the “memory-effe ct” quite as much. Following the pr oper steps for charging and dischar ging in NiMH batteries is very impo rtant. NiMh batteries need smart ch argers which prevent them from over -charging. It is also important tha t they are not run flat in a portab le device, which creates reverse ch arging, which can completely damage the battery. Most devices detect s afe discharge voltage and shut down automatically. In this case, NiMH batteries are much more effective i n high drainage devices like digita l cameras, while NiCad batteries ar e more effective in devices with a fast discharge rate such as power t ools. NiMH batteries are also used in hybrid cars. The newest and most powerful of all rechargeable battery types is the Lithium Ion battery. When compared to NiCad and NiMh batteries, Li-Ion batteries have the highest voltage density and the lowest self-discha rge rate. It is the smallest and mo st light-weight of all the batterie s, but all the advantages make it m uch more expensive as well. New Li- Ion batteries are said to charge 10 times faster than NiMH or NiCad ba tteries, and does so in a fraction of the time. Li-Ion are extremely s usceptible to high temperatures whi ch can great shorten their lifetime . Extremely high temperatures can a lso cause a Li-Ion battery to explode. Different types of batteries have t heir advantages and disadvantages. While some offer more convenience a nd higher capacity, there are still many limitations facing the develo pment of batteries. However, batter y technology is improving everyday to help portable devices last longer.
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