Groundsmaster 4300--DPage 5 -- 46Electrical 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(5.5
o
C) above 80
o
F (26.7
o
C) add 0.004 to the
specific gravity reading. For each 10
o
F(5.5
o
C) be-
low 80
o
F (26.7
o
C) subtract 0.004 from the specific
gravity reading.
Example: Cell Temperature 100
o
F
Cell Gravity 1.245
100
o
F minus 80
o
F equals 20
o
F
(37.7
o
C minus 26.7
o
C equals 11.0
o
C)
20
o
F multiply by 0.004/10
o
F equals 0.008
(11
o
C multiply by 0.004/5.5
o
C equals 0.008)
ADD (conversion above) 0.008
Correction to 80
o
F (26.7
o
C) 1.253
C. If the difference between the highest and lowest
cell specific gravity is 0.050 or greater or the lowest
cellspecific gravity is lessthan1.225,charge the bat-
tery. Charge at the recommended rate and time giv-
en in Battery Charging in this section or until
specific gravity of all cells is 1.225 or greater with the
differenceins pecific gravity betweenthehighestand
lowest cell less than 0.050. If these charging condi-
tions can not be met, replace the battery.
2. Perform a high--discharge test with an adjustable
load tester.
Thisisoneofthe most reliable means of testing a battery
asitsimulatesthecold--crankingtest.A commercial bat-
tery load tester is required to perform this test.
CAUTION
Follow the battery load tester manufacturer’s
instructions when using 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 (see battery charging
in this section).
B. If the battery has recently been charged, remove
the battery surface charge before performing the
load test. Disconnectthe enginefuelstop solenoid to
prevent the engine from starting. Engage the starter
motor for ten (10) seconds to remove batterysurface
charge. Reconnect the fuel stop solenoid.
C. Make sure batteryterminals arefree 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. Applyatestloadof295 amps (one half the Crank-
ing Performance rating of the battery) for 15 se-
conds.
G. Take a battery voltage reading after 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 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 -- 1 2
o
C
8.5 0
o
F -- 1 8
o
C
I. If the testvoltage is belowthe minimum voltagein
the chart, replace the battery. If the test voltage is at
or above the minimum, return the battery to service.
