TM 11-6140-203-14-1
operating temperature range as 65F to + 165F. Its
of capacity and an imbalance of cells within a nickel-
output capacity will be considerably degraded at both
cadmium battery.
extremes.
b. Slow deep cycle discharge to 0 volt followed by
a. Charging. Charging at low temperatures requires
charge is necessary to equalize cells within a nickel-
more time and higher charging voltages than at nor-
cadmium battery.
mal temperatures. In general, the lower the battery
c. Cells containing plastic film separators are more
temperature, the longer the time required for charg-
resistant to thermal runaway than cellophane sep-
ing. Conversely, charging at high temperatures re-
arated ones.
quires lower charging voltages.
d. Nickel-cadmium battery temperature rise above
b. Discharge Voltage. The voltage decreases with an
130F may cause thermal runaway.
increase in discharge rate and a decrease in tempera-
e. Charging at low temperature requires more time
ture.
and/or higher charging voltage.
2-17. Summary of Factors Affecting Serv-
iceability
a. Shallow discharge cycles result in temporary loss
Section IV. GENERAL SERVICING FEATURES
sonnel are qualified and fully aware of proper safety
precautions. Figure 2-10 illustrates the equipment
Nickel-cadmium batteries are rugged and provide long
layout of a typical nickel-cadmium battery shop.
life. However, they require proper handling and main-
c. If a shortage of tools exists and it becomes neces-
tenance if they are to deliver designed output and are
sary to use the same tools for both types of batteries,
to have a maximum useful life. Certain general han-
be absolutely sure to wash and rinse the tools with
dling techniques and precautions must be observed.
a. The electrolyte in nickel-cadmium batteries con-
plenty of clean, hot water after they are used on either
type. Use plenty of strong soap. Potassium hydroxide
tains potassium hydroxide and distilled water. Chem-
will give the tools a very slippery, soapy feeling. To
ically, this is the exact opposite of an acid. Lead-acid
speed up the cleaning, if available, use a mild solution
batteries use sulphuric acid. Take every step possible
of vinegar to wash the tools. Dip the tools in the
to keep the nickel-cadmium batteries as far away as
vinegar solution, rinse in warm tap water, and then
possible from the lead-acid type batteries. Do not use
rinse in distilled water.
the same tools and materials (screwdrivers, wrenches,
d. When working around batteries, use the apron,
syringes, hydrometers, gloves, apron, etc.) for both
gloves, and goggles or face-shield provided. If you spill
batteries. Anything associated with the lead-acid type
any potassium hydroxide on your skin, immediately
battery (even air) must never come in contact with the
flood the area with cold water and seek medical aid.
nickel-cadmium battery or the electrolyte. Even a
CAUTION
trace of sulphuric acid fumes from a lead-acid battery
Do not use a wire brush. Do not attempt to
mixing with the electrolyte for the nickel-cadmium
clean the battery shops with solvents, acids,
battery may result in damage to the nickel-cadmium
or any chemical solvents because the bat-
battery.
teries are constructed with plastic cells
b. If separate battery shops are not possible, setup
which would be damaged by contact with
bench facilities at opposite ends of the battery shop.
such chemicals. Keep open flames and metal
Mark each area of the battery shop clearly. Keep tools
objects, such as tools, etc., away from the ex-
and materials separate. The nickel-cadmium area
posed parts of the battery. If objects are acci-
should be free of all contamination. Markings that
dentally dropped across the terminals, a
identify the tools and materials for use with nickel-
short circuit could cause damage to one or
cadmium batteries will insure that contamination will
more cells.
not occur. Painting the color blue is recommended on
e. The white powder found on top of the cells and
the tools and materials used with nickel-cadmium bat-
cell connectors is potassium carbonate and is formed
teries. Painting the color pink is recommended on the
when the potassium hydroxide reacts with the carbon
tools and materials used with lead-acid batteries. The
dioxide in the air. Potassium carbonate deposits in the
use of properly trained personnel in the maintenance
dry state are nonconductive and when in contact with
of nickel-cadmium batteries is most important. In ad-
nickel or nickel-plated material is noncorrosive. When
dition, strict adherence to the maintenance procedures
moisture is added to the powder, which occurs with
prescribed for nickel-cadmium batteries is equally im-
drastic humidity changes, an electrical leakage path is
portant. The authority responsible for battery mainte-
established. Also, if the potassium carbonate comes in
nance must insure that all battery maintenance per-
