Service Manual

Groundsmaster 4100--D/4110--DPage 5 -- 46Electrical System
2. 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 r eading. 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
cellspecificgravityis lessthan1.225,chargethebat-
tery. Charge at the recommended rate and time giv-
en in Charging or until all cells specific gravity is
1.225or greater with thedifferencein specific gravity
between the highest and lowest cell less than 0.050.
If these c harging conditions can not be met, replace
the battery.
3. Perform a high--discharge test with an adjustable
load tester.
Thisisoneofthemostreliable meansoftestingabattery
asitsimulatesthecold--crankingtest.A commercialbat-
tery load tester is required to perform this test.
CAUTION
Follow the manufacturer’s instructions when us-
ing a battery 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 before continuing with
load testing procedure.
B. If the battery has recently been charged, apply a
150 amp load for 15 seconds to remove the surface
charge. Use a battery load tester following the
manufacturer’s instructions.
C. Makesure batteryterminals are freeofcorrosion.
D. 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. Applya testloadof345amps(onehalfthebattery
cold cranking amp rating) for 15 seconds.
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 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 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.