2
Increasing demand for portable DC
power has risen from improvements
in battery and motor design technol-
ogy. More than ever before, portable
DC powered products have become
available in many diverse applications.
Rechargeable batteries appear in all
types of products from analytical
electronic equipment to power tools
and toys. In some instances, these
diverse applications pose different
requirements on the source of DC
Power. Fortunately, availability of
many types of battery chemistries
yield unique characteristics. Table 1
contains just some of t he different
battery types and their advantages.
Whether testing batteries in R&D or
production environments, the test
requirements for each of the different
battery types are basically the same.
Figure 1 shows a common test config-
uration. In general, the t esting of a
battery involves discharging it over
a period of time to determine several
specifications. This application note
will concentrate on the test of second-
ary batteries because they require
additional tests involving recharging.
Nickel-cadmium batteries, in partic-
ular, are discussed because they are
the most universally used type of
secondary battery in t oday’s demand-
ing applications.
Introduction
Table 1. Characteristics and Applications of Different Battery Types
Nickel- Gelled Lead Lithium Carbon Alkaline Silver Mercuric
Cadmium Acid Zinc Oxide Oxide
Volts/Cell 1.2 2.0 1.5 to 1 1.5 1.5 1.5 1.4
Applications portable standby service, memory backup, average use good general button-sized button-sized cells
equipment, rechargeable pacemakers, purpose battery cells for watches for watches and
rechargeable electronic and hearing aids hearing aids
door locks,
emergency
locator
transmitters
Charge CC CV, float charge N/A N/A N/A N/A N/A
Method
Cycle Life 500+ cycles 200 cycles N/A N/A N/A N/A N/A
Life 3 mos. 1 year 5 to 10+ years 1 to 5 years 5% loss/yr. 6% loss/yr. 4% loss/yr.
(Charged) (–2%/day)
Operating 20°C to 70°C –20°C to 65°C –55°C to 75°C –5°C to 55°C –30°C to 55°C –20°C to 55°C –10°C to 55°C
Temp.
Performance high discharge high capacity flat discharge, low cost, good energy flat discharge, flat discharge
Comments rate, quick long life, wide sloping density, more energy
charge rate temperature discharge, sloping per unit
range, good low energy discharge volume than
energy density density mercuric oxide
Figure 1. Common Test Configuration