Komatsu 930E-2 Shop Manual page 122

To remove corrosion, clean the battery with a solution
of ordinary baking soda and a stiff, non-wire brush and
flush with clean water. Make sure none of the soda
solution is allowed into the battery cells. Be sure termi-
nals are clean and tight. Clean terminals are very im-
portant in a voltage regulated system. Corrosion
creates resistance in the charging circuit which causes
undercharging and gradual starvation of the battery.
NOTE: When washing batteries, make sure cell caps
are tight to prevent cleaning solution from entering the
cells.
Addition of acid will be necessary if considerable elec-
trolyte has been lost through spillage. Before adding
acid, make sure battery is fully charged. This is accom-
plished by putting the battery on charge and taking
hourly specific gravity readings on each cell. When all
the cells are gassing freely and three successive hourly
readings show no rise in specific gravity, the battery is
considered charged. Additional acid may now be
added. Continue charging for another hour and again
check specific gravity. Repeat the above procedure
until all cells indicate a specific gravity of 1.260-1.265
corrected to 80°F (27°C).
NOTE: Use 1.400 strength sulphuric acid when making
specific gravity adjustments. Acid of higher strength
will attack the plates and separators before it has a
chance to diffuse into the solution.
If the temperature of the electrolyte is not reasonably
close to 80°F (27°C) when the specific gravity is taken,
temperature should be corrected to 80°F (27°C):
• For every 10°F (5°C) below 80°F (27°C), 0.004
should be SUBTRACTED from the specific gravity
reading.
• For every 10°F (5°C) above 80°F (27°C), 0.004
should be ADDED to the reading.
Idle batteries should not be allowed to stand unat-
tended. If equipment is to stand unused for more than
two weeks, the batteries should be removed and
placed in a cool, dry place where they may be checked
periodically and charged when necessary. Remember,
all lead-acid batteries discharge slowly when not in use.
This self discharge takes place even though the battery
is not connected in a circuit and is more pronounced
in warm weather than in cold.
D2-2
The rate of self-discharge of a battery kept at 100°F
(38°C) is about six times that of a battery kept at 50°F
(10°C) and self-discharge of a battery kept at 80°F
(27°C) is about four times that one at 50°F (10°C). Over
a thirty day period, the average self-discharge runs
about 0.002 specific gravity per day at 80°F (27°C).
To offset the results of self-discharge, idle batteries
should receive a booster charge (not a quick charge)
at least once every thirty days. Batteries allowed to
stand for long periods in a discharged condition are
attacked by a crystallization of the lead sulfate on the
plates. Such batteries are called sulfated and are, in the
majority of cases, irreparably damaged. In less severe
cases, the sulfated battery may be restored to limited
service by prolonged charging at a low rate (approxi-
mately
An undercharged battery is extremely susceptible to
freezing when allowed to stand in cold weather.
The electrolyte of a battery in various stages of charge
will start to freeze at temperatures indicated in the table.
The temperatures in the table below indicate the points
at which the first ice crystals appear. Lower tempera-
tures must be reached for a solid freeze. Solid freezing
of the electrolyte may crack the battery case and
damage the positive plates. As will be noted, a
charged battery is in no danger of freezing, therefore,
⁄
a charge or better is desirable, especially during
3
4
winter weather.
SPECIFIC GRAVITY
Corrected to 80°F (27°C)
24VDC Electric Supply System
⁄
.
normal rate)
1
2
TEMPERATURE -
1.280
1.250
1.200
1.150
1.100
⁄
3
4
FREEZING
DEGREES
-90°F (-70°C)
-60°F (-54°C)
-16°F (-27°C)
+ 5°F (-15°C)
+ 19°F (-7°C)
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