Undercharged Battery

TOOL REQUIRED:
J 39200 Digital Multimeter

An undercharged battery is usually characterized by slow cranking or by a dark battery hydrometer. If this condition exists, check the following items for a cause:
1. Determine that the undercharged condition has not been caused by leaving accessories on for extended periods without charging the battery.
2. Check the drive belt for proper tension.
3. If battery fault is suspected, refer to Battery. Battery
4. Inspect the wiring for faults. Check that all connections are clean and tight. Also check that all bulkhead connectors are tight and undamaged. Battery cable connections at the battery, starter and engine ground points should also be checked.

Regulator Setting Voltage - Voltage vs. Temperature:

5. With all accessories turned off, connect a J 39200 across the battery. Run the engine at a moderate speed and check the voltage, taking into account the temperature the generator is exposed to during the test. As the temperature of the regulator case in the generator increases, the voltage output will decrease. The standard regulator voltage setting is 14.2 to 14.8 volts at 2°C (7°F). The minimum operating voltage should be 13.5 volts. If the voltage is at 13.5 volts or more, proceed to Step 6. If the voltage is less than 13.5 volts, remove the generator.
6. If Steps 1 through 5 have not produced satisfactory results, perform the following generator test:
A. Disconnect the negative (-) battery cable.
B. Remove the rubber protector, nut and generator battery terminal wire.
C. Connect an ammeter between the generator and the disconnected wire. Connect the ammeter black lead to the wire and the ammeter red lead to the generator battery terminal.
D. Connect a J 39200 between the generator battery terminal and chassis ground.
E. Start and run engine at 2000 RPM. Turn all accessories and high-beam headlamps on. Turn the blower to HIGH. Ground the generator F terminal with a screwdriver.
F. Adjust engine speed to obtain the maximum current output.
G. If the current output is within 10 amperes of the maximum rating and the voltage reading is 13.5 to 16.0 volts, the generator is not faulty and is not the cause of an undercharged battery condition. Refer to "Generator Usage Chart". If the current output is not within 10 amperes of the maximum rating, or the voltage reading is less than 13.5 volts, remove the generator.