Case 580SR Service Manual page 991

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7.5 TESTS
Before commencing battery tests check the battery
for clogged vents, corrosion, raised vent plugs or a
cracked case.
Test equipment required:
Z Hydrometer.
Z Battery starter tester (High rate discharge tester).
Z Thermometer.
Z Battery Charger.
SPECIFIC GRAVITY
This test will determine the state of battery charge.
1. With the float in the vertical position take the
reading.
2. Adjust the hydrometer reading for electrolyte
temperature variations by subtracting 4 points
(0.004 specific gravity) for every 5.5 °C below
the temperature at which the hydrometer is cal-
ibrated and by adding 4 points (0.004 specific
gravity) for every 5.5 °C above this temperature.
The following examples are calculated using a hy-
drometer calibrated at 30 °C.
Example 1:
Temperature below 30 °C
Electrolyte temperature...................................19 °C
Hydrometer reading ........................................1.270
Subtract (11.0 / 5.5) x 0.004 ...........................0.008
Corrected specific gravity................................1,262
Example 2:
Temperature above 30 °C
Electrolyte temperature...................................40 °C
Hydrometer reading ........................................1.220
Add (10.0 / 5.5) x 0.004 ..................................0.007
Corrected specific gravity................................1.227
3. Use the following table to determine the state of
charge.
State of
Charge
100%
75%
50%
25%
Discharged
NOTE: specific gravity should not vary more than
0.025 points between cells.
SECTION 55 - ELECTRICAL SYSTEM
Corrected Corrected
specific specific
gravity @ gravity @
15 °C 25 °C
1.295 1.287
1.253 1.246
1.217 1.210
1.177 1.170
1.137 1.130
4. If the specific gravity is 1.280 or more the battery
is fully charged and in good operating condition.
5. Should the corrected specific gravity be below
1.280, charge the battery and inspect the charg-
ing system to determine the cause of the low
battery charge.
NOTE: if distilled water has recently been added the
battery should be recharged for a short period oth-
erwise accurate hydrometer readings will not be ob-
tained.
If the battery has been charged under static condi-
tions, denser electrolyte will accumulate at the bot-
tom of the cells. The battery should be shaken
periodically to mix the electrolyte, this will improve
the charge rate and provide a more accurate hy-
drometer reading when tested.
PERFORMANCE TEST
The performance test is to determine if the battery
has adequate capacity to turn the engine. The volt-
age reading obtained is used to determine the bat-
tery condition. Prior to testing, ensure the electrolyte
level is correct and the open circuit voltage is 12.5 V
or more.
The battery may be tested on or off the loader back-
hoe.
1. Set the current control switch of the battery
starter tester (high rate discharge tester) to the
"off" position and the voltage selector switch
equal to, or slightly higher than, the rated battery
voltage. Connect the tester positive leads to the
battery positive terminal and the negative leads
to the negative battery terminal.
2. Turn the current control knob until the ammeter
reading is half the CCA rating of the battery and
take the voltage reading.
Average
Z If the reading is 9.6 volts or more after 15 seconds,
battery
the battery has an acceptable output capacity and
voltage
will readily accept a normal charge.
Z If however the reading is below 9.6 volts, the bat-
tery is considered unsatisfactory for service and
2.76
should be test charged as described below.
12.52
12.30
S
CAUTION
12.06
Do not leave the high discharge load on the battery
11.84
for periods longer than 15 seconds.
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