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During the last decade, rechargeable batteries
have made little improvement in terms of increased capacity.
Compared with the vast advancements in areas such as micro electronics,
the lack of progress in battery technology is apparent. Consider,
for example, a computer memory core of the sixties and compare
it to a modern microchip of the same byte count; what once measured
a cubic foot now sits in a tiny chip. A comparable size reduction
would literally shrink a heavy duty car battery to the size
of a coin. Since batteries are still based on chemical processes,
a car battery the size of a coin is still some time off.
What research has brought about is a number of different battery
chemistries, each offering distinct advantages over the others
but none providing a fully satisfactory solution. Today's most
common and promising chemistries available are: |
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Nickel
Cadmium |
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Lithium Ion
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(NiCd) - used for portable radios,
cellular phones, video cameras, power tools and some biomedical
instruments. NiCds have a good load characteristics, are
economically priced and are simple to use. |
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(Li-Ion) - available only in limited
supply and presently used for some video cameras, cell
phones, high volumes applications . When readily available,
this chemistry will replace some NiCds for high energy-density
applications, but at a higher cost. |
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Nickel Metal
Hydride |
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Lithium Polymer |
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(NiMH) - used for cellular phones
and laptop computers where high-energy is of importance
and cost is secondary. |
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(Li-Polymer) - when commercially
available, this battery will have the highest energy density
and lowest self-discharge but its load characteristics
will only suit low current applications.
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Sealed Lead Acid
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(SLA) - used for biomedical equipment,
wheel chairs, UPS systems and other heavier applications
where energy-to-weight ratio is not critical and low battery
cost is desirable. |
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Choice of Battery
Chemistries
Battery Maintenance |
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