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3.6 Discharge curves for common batteries

they typically have a greater electrical capacity than rechargeables.
If one is engaged in a function (i.e., a robotic war) that requires the
highest power density available for one-shot use, primary batteries
may be the way to go.

Rating primary batteries
As you may have guessed, there are a number of primary batteries
available. The differences in batteries relate to the chemistry used
in the battery to produce electricity. The choice of a primary battery
30 is a tradeoff of price versus energy density, shelf life, temperature
range, discharge slope, and peak current capacity.
Carbon-zinc At the low end of primary batteries is the carbon-zinc
battery. This battery hasn’t changed much since 1868 when it was
developed by George Leclanche. The carbon battery has a low
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energy density [1 to 2 watthours per cubic inch (Wh/in )], poor
high-current performance, sloping discharge curve, and bad
low-temperature performance. It is inexpensive but obsolete.

Alkaline-manganese This is simply an alkaline battery. It has an en-
3
ergy density of 2 to 3 Wh/in , improved low-temperature perfor-
mance, and a sloping discharge curve, not as severe as carbon-zinc
batteries. Its cost is moderate.

Lithium This is a premium battery with a high energy density (8
3
Wh/in ), excellent low-temperature and high-temperature perfor-
mance, and a long shelf life (15 years). It is also lightweight, but
expensive.
Secondary batteries
Secondary batteries are rechargeable. The most common
rechargeable batteries are NiCds and lead-acid. We will start
with NiCd batteries.
Team LRN
Chapter three