Page 106 - Concise Encyclopedia of Robotics

Electrochemical Power
also lasts longer in most electronic devices, and is therefore preferred for
use in transistor radios, calculators, and portable cassette players. Its shelf
life is much longer than that of a zinc–carbon cell.
Transistor batteries are small, 9-V, box-shaped batteries with clip-on
connectors on top. They consist of six tiny zinc–carbon or alkaline cells
in series. These batteries are used in low-current electronic devices, such
as portable earphone radios, radio garage-door openers, television and
stereo remote-control boxes, and electronic calculators.
Lantern batteries are rather massive, and can deliver a fair amount of
current. One type has spring contacts on the top. The other type has
thumbscrew terminals.Besides keeping an incandescent bulb lit for a while,
these batteries, usually rated at 6 V and consisting of four zinc–carbon or
alkaline cells, can provide enough energy to operate a low-power com-
munications radio or a small mobile robot.
Silver-oxide cells are usually made into a buttonlike shape, and can fit
inside a wristwatch. They come in various sizes and thicknesses, all with
similar appearance. They supply 1.5 V and offer excellent energy storage
for the weight. They have a flat discharge curve. Silver-oxide cells can be
stacked to make batteries about the size of an AA cylindrical cell.
Mercury cells, also called mercuric oxide cells, have advantages similar
to silver-oxide cells. They are manufactured in the same general form. The
main difference, often not of significance, is a somewhat lower voltage
per cell: 1.35 V.There has been a decrease in the popularity of mercury cells
and batteries in recent years, because mercury is toxic and is not easily
disposed of.
Lithium cells supply 1.5 to 3.5 V,depending on the chemistry used.These
cells, like their silver-oxide cousins, can be stacked to make batteries.
Lithium cells and batteries have superior shelf life, and they can last for
years in very-low-current applications. They provide excellent energy
capacity per unit volume.
Lead–acid cells and batteries have a solution or paste of sulfuric acid,
along with a lead electrode (negative) and a lead-dioxide electrode (pos-
itive). Paste-type lead–acid batteries can be used in consumer devices
that require moderate current, such as laptop computers, portable
VCRs, and personal robots. They are also used in uninterruptible power
supplies for personal computers.
Nickel-based cells and batteries
NICAD cells come in several forms. Cylindrical cells look like dry cells.
Button cells are used in cameras, watches, memory backup applications,
and other places where miniaturization is important. Flooded cells are
used in heavy-duty applications, and can have a storage capacity of as

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