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Reelmaster 3550−D Page 5 − 49 Electrical System
Battery Testing
1. 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 tem-
perature of the cell.
B. Temperature correct each cell reading. For each
10
o
F (6
o
C) above 80
o
F (27
o
C) add 0.004 to the spe-
cific gravity reading. For each 10
o
F (6
o
C) below 80
o
F
(27
o
C) subtract 0.004 from the specific gravity read-
ing.
Example: Cell Temperature 100
o
F
Cell Gravity 1.245
100
o
F minus 80
o
F equals 20
o
F
(38
o
C minus 27
o
C equals 11
o
C)
20
o
F multiply by 0.004/10
o
F equals 0.008
(11
o
C multiply by 0.004/6
o
C equals 0.008)
ADD (conversion above) 0.008
Correction to 80
o
F (27
o
C) 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 giv-
en in Battery Charging or until all cells specific
gravity is 1.225 or greater with the difference in spe-
cific gravity between 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 battery load tester manufacturer’s
instructions when using a load tester.
A. Check the voltage across the battery terminals
prior to testing the battery. If the voltage is less than
12.4 VDC, recharge the battery.
B. If the battery has been charged, apply a 150 amp
load for fifteen (15) seconds to remove the surface
charge. Use a battery load tester following the
manufacturer’s instructions.
C. Make sure battery terminals are free of corrosion.
D. Measure the temperature of the center battery
cell.
E. Connect a battery load tester to the battery termi-
nals following the load tester manufacturer’s in-
structions. Connect a digital multimeter to the
battery terminals.
F. Apply a test load of 285 amps (one half the Crank-
ing Performance rating of the battery) for fifteen (15)
seconds.
G. Take a battery voltage reading after the load has
been applied to the battery for fifteen (15) seconds,
then remove the load. Record the voltage reading.
H. Using the table below, determine the minimum
voltage for the cell temperature reading:
Minimum
Voltage
Battery Electrolyte
Temperature
9.6 70
o
F (and up) 21
o
C (and up)
9.5 60
o
F 16
o
C
9.4 50
o
F 10
o
C
9.3 40
o
F 4
o
C
9.1 30
o
F −1
o
C
8.9 20
o
F −7
o
C
8.7 10
o
F −12
o
C
8.5 0
o
F −18
o
C
I. If the test voltage is below the minimum, replace
the battery. If the test voltage is at or above the mini-
mum, return the battery to service.
Electrical
System