The Nickel Cadmium (NiCd) Battery
Alkaline nickel battery technology
originated in 1899, when Waldmar Jungner invented the NiCd
battery. The materials were expensive compared to other battery
types available at the time and its use was limited to special
applications. In 1932, the active materials were deposited
inside a porous nickel-plated electrode and in 1947, research
began on a sealed NiCd battery, which recombined the internal
gases generated during charge rather than venting them. These
advances led to the modern sealed NiCd battery, which is in
use today.
The NiCd prefers fast charge to slow charge and pulse charge
to DC charge. All other chemistries prefer a shallow discharge
and moderate load currents. The NiCd is a strong and silent
worker; hard labor poses no problem. In fact, the NiCd is
the only battery type that performs best under rigorous working
conditions. It does not like to be pampered by sitting in
chargers for days and being used only occasionally for brief
periods. A periodic full discharge is so important that, if
omitted, large crystals will form on the cell plates (also
referred to as 'memory') and the NiCd will gradually lose
its performance.
Among rechargeable batteries, NiCd remains a popular choice
for applications such as two-way radios, emergency medical
equipment, professional video cameras and power tools. Over
50 percent of all rechargeable batteries for portable
equipment are NiCd. However, the introduction of batteries
with higher energy densities and less toxic metals is causing
a diversion from NiCd to newer technologies.
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Advantages
and Limitations of NiCd Batteries
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Advantages
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Fast and simple charge — even after prolonged storage.
High number of charge/discharge cycles — if properly
maintained, the NiCd provides over 1000 charge/discharge
cycles.
Good load performance — the NiCd allows recharging
at low temperatures.
Long shelf life – in any state-of-charge.
Simple storage and transportation — most airfreight
companies accept the NiCd without special conditions.
Good low temperature performance.
Forgiving if abused — the NiCd is one of the most rugged
rechargeable batteries.
Economically priced — the NiCd is the lowest cost battery
in terms of cost per cycle.
Available in a wide range of sizes and performance
options — most NiCd cells are cylindrical.
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Limitations
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Relatively low energy density — compared with newer
systems.
Memory effect — the NiCd must periodically be exercised
to prevent memory.
Environmentally unfriendly — the NiCd contains toxic
metals. Some countries are limiting the use of the NiCd
battery.
Has relatively high self-discharge — needs recharging
after storage.
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Figure 2-2:
Advantages and limitations of NiCd batteries.
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