Komatsu 830E Shop Manual page 120

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
electrolyte has been lost through spillage. Before
adding acid, make sure battery is fully charged. This
is accomplished by putting the battery on charge and
taking hourly specific gravity readings on each cell.
When all the cells are gassing freely and three suc-
cessive hourly readings show no rise in specific grav-
ity, 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 sulfuric 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 (19° 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-dis-
charge 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
(approximately normal rate).
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 table I indicate the points at
which the first ice crystals appear. Lower tempera-
tures must be reached for a solid freeze. Solid freez-
ing 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 win-
ter weather.
Specific Gravity
Corrected to 80° F
24 VDC Electric Supply System
Freezing Temperature
(27° C)
1.280 -90°F (-70° C)
1.250 -60°F (-54° C)
1.200 -16°F (-27° C)
1.150 +5° F (-15° C)
1.100 +19° F (-7° C)
TABLE I.
Degrees
D02023