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NiCad__Lithium__and_NiMH_Batteries

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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.

				
Monika Kamal Monika Kamal Jesus http://ineed4u.blogspot.com/
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