Actron KAL4780 - Manual (Page 7)

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3. Have an assistant turn the ignition switch to the Start Position and crank engine
for 15 seconds. If working alone, use a remote starter switch. Do not press the
Load Switch. Observe the battery voltage indicated on the display.
4. A healthy starting system, with a good, fully charged battery, should read above
9.0V during this test.
5. Readings below 9.0V may indicate a problem in the starting system. Recharge
battery and repeat this test. If voltage readings still remain below 9.0V, then
probably either the battery is bad (perform the Load Test), the starter is defec-
tive or the cables are loose or corroded.
Charging Test
This test measures the battery voltage while the engine is running to determine if
the charging system is operating properly.
1. Start the vehicle and allow it to warm-up. This may take 10 to 15 minutes.
2. Turn engine OFF.
3. When performing the Charging Test, the battery should be partially discharged.
Turn the ignition switch to the ACCESSORIES position and turn headlights ON
and fan to HIGH for 1 minute.
4. When done, turn headlights and fan OFF and then turn ignition switch to the
OFF position.
5. While observing polarity, connect the tester across the battery posts: Red to
positive (+), Black to negative (-). Refer to Figure 6.
6. Start engine and run at fast-idle (1200-1500 RPM). A healthy 12V charging
system should maintain readings between 13.5V and 15.5V.
Proper Charging System Operation
Within several minutes, the voltage will gradually increase to the regulated
voltage range of 13.5V to 15.5V. In a 6V system, the voltage should gradually
rise to the regulated voltage range of 6.7V to 7.4V.
Incorrect Charging System Operation
Low Regulated Voltage: If after several minutes, the voltage is below 13.5V
for a 12V system (6.7V for a 6V system), than a problem exists with either the
charging system or battery. Perform the Load Test on the battery and then
repeat the Charging Test.
High Regulated Voltage: If the voltage is above the regulated voltage limit
(15.5V for a 12V system, 7.4V for a 6V system), then a problem exists in the
charging system. Damage to the vehicle electrical system may result from the
excessively high voltage.
A decision to REPLACE the alternator or other electrical system components
should not be based solely on these test results. Refer to the applicable vehicle
service manual for additional test and troubleshooting procedures.