Alternator: Testing and Inspection

Fig. 1 Alternator test connections:

1. Ensure all battery and alternator connections are satisfactory and drive belt and battery are in good condition.
2. Connect voltmeter across battery terminals and run engine at 3000 RPM with no additional load placed on electrical system. Voltmeter should indicate 13-14.5 volts after two minutes of operation.
3. With voltmeter still connected across battery terminals, connect ammeter to charging circuit as shown in Fig. 1.
4. Run engine at 2400-2550 RPM with all electrical accessories turned on to ensure maximum charging current is reached. Also, ensure regulated voltage does not drop below 12.7 volts. After engine has been started, the ammeter reading will gradually decrease as the battery approaches a fully charged condition. Read the ammeter indication at its maximum value while increasing engine RPM.