The most common form of stored electrical
energy is the dry cell battery.
Dry cells
drive radios, clocks, and mp3
players. All
dry cells derive their electrical
energy
from a chemical reaction that
occurs between
a core and a surrounding near
liquid acidic
fluid. These batteries come in
several many
different packages, but the most
common are:
- AAAA, AAA, AA, C, and D batteries are cylinders increasing in size up to about
one and a quarter inch in diameter and almost
two inches long. All of these batteries produce
1.5 volts and are used, often in several
at once, in everything from flashlights to
digital cameras.
- 6 volt batteries are often called lantern batteries. They are rectangular blocks about two and
one-half inches on a side and about four
inches tall with two coil terminals on the
top. They acquired their name from their
original use in camp lights and signal lanterns.
- 9 volt batteries are often called transistor batteries from
their early use in portable transistor radios.
They come as small rectangular cans about
an inch by two-thirds of an inch and two
inches tall. Today they are the most common
battery for smoke detectors.
Regardless of package, the chemical composition
of the acidic solution inside the battery
is one of three common kinds:
- Carbon zinc batteries were the earliest available technology,
but they now are less popular even though
least expensive because they tend to have
short shelf lives, work poorly in the cold,
and leak when the contents erode the battery
walls. They remain attractive for low drain
uses in clocks and timers because of cost.
- Alkaline batteries are the most common available
today. They tend not to discharge as quickly
while awaiting use, maintain their voltage
better with decreasing temperature, and remain
intact longer because their contents are
less corrosive. Alkaline batteries have a
good balance of cost with lifetime in most
common applications.
- Lithium batteries have enjoyed recent popularity
because of their ability to deliver current
on demand in products like cameras with built
in flashes. A lithium battery can repeatedly
meet the surge demand of these products where
an alkaline battery will be quickly depleted.
Lithium batteries tend to be the most expensive
batteries generally available.
Mercury and silver are also found in speciality applications
like batteries for watches and hearing aids
because of their ability to deliver power
from smaller packages. |
