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Introduction
During the last few decades, rechargeable batteries have
made only moderate improvements in terms of higher capacity
and smaller size. Compared with the vast advancements in areas
such as microelectronics, the lack of progress in battery
technology is apparent. Consider a computer memory core of
the sixties and compare it with 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 an electrochemical process, a
car battery the size of a coin may not be possible using our
current techniques.
Research has brought about a variety of battery
chemistries, each offering distinct advantages but none providing
a fully satisfactory solution. With today’s increased selection,
however, better choices can be applied to suit a specific
user application.
The consumer market, for example, demands high
energy densities and small sizes. This is done to maintain
adequate runtime on portable devices that are becoming increasingly
more powerful and power hungry. Relentless downsizing of portable
equipment has pressured manufacturers to invent smaller batteries.
This, however, must be done without sacrificing runtimes.
By packing more energy into a pack, other qualities are often
compromised. One of these is longevity.
Long service life and predictable low internal
resistance are found in the NiCd family. However, this chemistry
is being replaced, where applicable, with systems that provide
longer runtimes. In addition, negative publicity about the
memory phenomenon and concerns of toxicity in disposal are
causing equipment manufacturers to seek alternatives.
Once hailed as a superior battery system, the
NiMH has also failed to provide the universal battery solution
for the twenty-first century. Shorter than expected service
life remains a major complaint.
The lithium-based battery may be the best choice,
especially for the fast-moving commercial market. Maintenance-free
and dependable, Li-ion is the preferred choice for many
because it offers small size and long runtime. But this battery
system is not without problems. A relatively rapid aging process,
even if the battery is not in use, limits the life to between
two and three years. In addition, a current-limiting safety
circuit limits the discharge current, rendering the Li-ion
unsuitable for applications requiring a heavy load. The Li-ion
polymer exhibits similar characteristics to the Li-ion.
No major breakthrough has been achieved with this system.
It does offer a very slim form factor but this quality is
attained in exchange for slightly less energy density.
With rapid developments in technology occurring
today, battery systems that use neither nickel, lead nor lithium
may soon become viable. Fuel cells, which enable uninterrupted
operation by drawing on a continuous supply of fuel, may solve
the portable energy needs in the future. Instead of a charger,
the user carries a bottle of liquid energy. Such a battery
would truly change the way we live and work.
This book addresses the most commonly used consumer and industrial
batteries, which are NiCd, NiMH, Lead Acid, and Li-ion/polymer.
It also includes the reusable alkaline for comparison. The
absence of other rechargeable battery systems is done for
reasons of clarity. Some weird and wonderful new battery inventions
may only live in experimental labs. Others may be used for
specialty applications, such as military and aerospace. Since
this book addresses the non-engineer, it is the author’s wish
to keep the matter as simple as possible.
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