Group 12, Battery
12-1-6 • Battery Service SM 765, Nov ’06
Keeping Battery Records
Records should be maintained to get the best service out
of your battery and truck.
These records should contain:
• Test Date. Each test should be dated for future ref-
erence and comparison.
• Specific Gravity and Temperature Readings.
Each battery cell should be checked and recorded
before and after charging. The specific gravity
reading of the electrolyte, calculated using a multi-
plier to account for the ambient temperature,
should not be less than 1.260. If below 1.250, the
battery should be recharged and tested.
• Variation Between Each Cell Tested. The varia-
tion in specific gravity reading between cells
should not be greater than 15 points (0.015). If
readings are greater, there are defective cells.
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The pilot cell should be changed occasionally
to distribute any electrolyte loss over the bat-
tery when taking readings.
• Load Voltage Tests should be performed and
recorded indicating the condition of a battery while
it is performing work.
• Actual Operating Hours of the Battery. Record
the actual time the battery is in use before putting it
on charger.
• Charging Time. Keep an accurate record of the
actual time the battery is on charger. After each
charge, check to see if the battery is fully charged.
Test the battery before placing it back into service.
Record these results.
• Visually Inspect for loose terminal connections or
posts, a cracked case, damaged cell covers (vent
caps), or excessive corrosion. This data should be
noted to help determine work environment and
possible trouble areas.
Battery Tests
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Use both tests described here.
Specific Gravity Test
Test at least six cells across battery with a temperaturecor-
rected hydrometer (see chart). Battery is fully charged
when the reading falls in the 1.280 to 1.300 range. If the
difference between cells is more than .015, battery needs
maintenance.
The battery specific gravity is an indication of the bat-
tery’s state of charge. You can determine the specific grav-
ity of the electrolyte solution in a battery with an
hydrometer. If the state of charge is low, the hydrometer
will read low. If the state of charge is high, the hydrometer
will read high.
For, example a reading from:
• 1.260 to 1.300 indicates a fully-charged battery.
• 1.200 to 1.220 indicates a battery is in a discharged
condition and cannot give satisfactory service.
Load Test
Put the main hydraulic system into tilt by-pass while read-
ing battery volts with a voltmeter.
Battery needs recharge or repair if voltage drops below
80% of the rated voltage of the battery.
Minimum acceptable readings:
• 80 volt battery: 64 volts
SPECIFIC GRAVITY TEST
SPECIFIC GRAVITY STATE OF CHANGE
1.260~1.300 100% CHARGED
1.230~1.250 75% CHARGED
1.200~1.220 50% CHARGED
1.170~1.190 25% CHARGED
1.140~1.160 VERY WEAK
1.110~1.130 DISCHARGED
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