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Workman HD Series Page 8 − 35 Electrical System
Battery Testing
1. If battery filler caps are removable, conduct a
hydrometer test of the battery electrolyte.
IMPORTANT: Make sure the area around the cells is
clean before opening the battery caps.
A. Measure the specific gravity of each cell with a
hydrometer. Draw electrolyte in and out of the
hydrometer barrel prior to taking a reading to warm−
up the hydrometer. At the same time take the temper-
ature of the cell.
B. Temperature correct each cell reading. For each
10F (5.5C) above 80F (26.7C) add 0.004 to the spe-
cific gravity reading. For each 10F (5.5C) below 80F
(26.7C) subtract 0.004 from the specific gravity read-
ing.
Example: Cell Temperature 100F
Cell Specific Gravity 1.245
100F minus 80F equals 20F
(37.7C minus 26.7C equals 11.0C)
20F multiply by 0.004/10F equals 0.008
(11C multiply by 0.004/5.5C equals 0.008)
ADD (conversion above) 0.008
Correction to 80F (26.7C) 1.253
C. If the difference between the highest and lowest
cell specific gravity is 0.050 or greater or the lowest
cell specific gravity is less than 1.225, charge the bat-
tery. Charge at the recommended rate and time given
in Charging or until all cells specific gravity is 1.225
or greater with the difference in specific gravity be-
tween the highest and lowest cell less than 0.050. If
these charging conditions can not be met, replace
the battery.
2. Perform a high−discharge test with an adjustable
load tester.
This is one of the most reliable means of testing a battery
as it simulates the cold−cranking test. A commercial bat-
tery load tester is required to perform this test.
CAUTION
Follow the manufacturer’s instructions when us-
ing a battery load tester.
A. Check the voltage across the battery terminals
prior to testing the battery. If the voltage is less than
12.4 VDC, charge the battery.
B. If the battery has been charged, apply a 150 amp
load for 15 seconds to remove the surface charge.
Use a battery load tester following the manufactur-
er’s instructions.
C. Make sure battery terminals are free of corrosion.
D. If battery filler caps are removable, measure the
temperature of the center cell.
E. Connect a battery load tester to the battery termi-
nals following the manufacturer’s instructions.
Connect a digital multimeter to the battery terminals.
F. Apply a test load of 270 amps (one half the Crank-
ing Performance rating of the battery) for 15 se-
conds.
G. Take a battery voltage reading at 15 seconds,
then remove the load.
H. Using the table below, determine the minimum
voltage for the cell temperature reading.
Minimum
Voltage
Battery Electrolyte
Temperature
9.6 70F (and up) 21.1
o
C (and up)
9.5 60F 15.6C
9.4 50F 10.0C
9.3 40F 4.4C
9.1 30F −1.1C
8.9 20F −6.7C
8.7 10F −12.2C
8.5 0F −17.8C
I. If the measured battery voltage is below the mini-
mum voltage shown in the table, replace the battery.
If the measured voltage is at or above the minimum
voltage shown in the table, return the battery to ser-
vice.
Electrical
System