ELECTRICAL SYSTEM
120
Battery Testers:
There are two major ways to check a battery’s opera-
tion :
• Load test that checks the out-put of the battery
after the fully charged battery has done a certain
amount of work. Fixed load testers are com-
monly available. Variable load testers are not
generally found in outdoor power equipment
repair shops, but are better for testing batteries.
• Capacitance test that checks the condition of the
battery plate core, regardless of the level of
charge.
Testing the battery:
1. Adjustable load testing
Adjustable load testing is used if an adjustable load
tester is available. Follow the procedures specified by
the manufacturer of the tester to connect to the battery.
1a. Disconnect the battery cables.
IMPORTANT: Disconnect the negative cable
first to help prevent a shorting hazard.
1b. Measure the temperature of the electro-
lyte.
1c. Connect a voltmeter and the load tester to
the appropriate terminals.
1d. Hook an amp probe onto the ground lead
of the load tester.
NOTE: A shunt can be used in place of the amp
probe, but a second voltmeter will be needed to
get a measurement from the shunt.
1e. Apply a load equal to 50% of the battery’s
rated CCA for 15 seconds.
NOTE: CCA stands for cold cranking amps. The
rating should be on the battery for aftermarket
batteries. For OEM batteries, contact the manu-
facturer for the CCA rating. Most riding mower
batteries are 200-275 CCA. See Figure 7.41.
1f. Record the voltage while the load was
applied. Compare the voltage to the follow-
ing chart:
1g. If the battery voltage is above what is listed
in the chart, the battery is good. If the bat-
tery voltage is below what is listed in the
chart, replace the battery.
Electrolyte
Temperature
Minimum
Required
Voltage
>70 deg. f. (21deg. c.)
9.6 V
60 deg. f. (16 deg. c.)
9.5 V
50 deg. f. (10 deg. c.)
9.4 V
40 deg. f. (4 deg. c.)
9.3 V
30 deg. f. (-1 deg. c.)
9.1 V
20 deg. f. (-7 deg. c.)
8.9 V
10 deg. f. (-12 deg. c.)
8.7 V
0 deg. f. (-18 deg. c.)
8.5 V
Figure 7.41
OEM batteries do not list the CCA’s
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