(5) Rotate the load control knob on the tester to
maintain 50% (260) of the battery cold crank rating
for a minimum 15 seconds (Fig. 5).
(6) After 15 seconds, record the loaded voltage
reading and return the load control to off.
(7) Voltage drop will vary according to battery
temperature at the time of the load test. Battery
temperature can be estimated by the temperature of
exposure over the preceding several hours. If the bat-
tery has been charged, boosted, or loaded a few min-
utes prior to the test, the battery would be slightly
warmer. Refer to Battery Load Test Temperatures
Table for proper loaded voltage reading.
(8) If battery passes load test, it is in good condi-
tion and further tests are not necessary. If it fails
load test, it should be replaced.
BATTERY OPEN CIRCUIT VOLTAGE TEST
An open circuit voltage no load test shows the
state of charge of a battery and whether it is ready
for a load test at 50 percent of the battery’s cold
crank rating. Refer to Battery Load Test. If a battery
has open circuit voltage reading of 12.4 volts or
greater, and will not pass the load test, replace the
battery because it is defective. To test open circuit
voltage, perform the following operation.
(1) Remove both battery cables, negative cable
first. Connect a Volt/Ammeter/Load tester (Fig. 6) to
the battery posts (Fig. 7).
(2) Allow the battery to stabilize for 2 minutes,
and then verify the open circuit voltage. Refer to Bat-
tery Open Circuit Voltage table.
(3) This voltage reading will approximate the state
of charge of the battery. It will not reveal battery
cranking capacity.
SERVICE PROCEDURES
BATTERY CHARGING
A battery is considered fully charged when it will
meet all the following requirements.
• It has an open circuit voltage charge of at least
12.4 volts (refer to Battery Open Circuit Voltage
table).
Fig. 5 Load 50% Cold Crank Rating
BATTERY LOAD TEMPERATURE TABLE
Minimum Voltage
Temperature
°F °C
9.6 volts 70° and above 21° and above
9.5 volts 60° 16°
9.4 volts 50° 10°
9.3 volts 40° 4°
9.1 volts 30° -1°
8.9 volts 20° -7°
8.7 volts 10° -12°
8.5 volts 0° -18°
Fig. 6 Testing Open Circuit Voltage
Fig. 7 Volt-Ammeter Load Tester Connections
8A - 6 BATTERY JA
DIAGNOSIS AND TESTING (Continued)
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