Generator — Testing in a Car (Opel Omega A)

1. If the alternator does not charge the battery, first check that the drive belt is not damaged and is in good condition and properly tensioned (Section 2). Also check the condition and safety of the generator electrical connections and battery wiring.

2. To accurately diagnose the generator's performance, special equipment and qualifications are required. For a rough, preliminary assessment, use a voltmeter (range from 0 to 15 or from 0 to 20 volts) as follows.

3. Connect a voltmeter in parallel to the battery terminals. Turn on the headlights and check the voltmeter readings: it should be between 12 and 13 V.

4. Start the engine and let it run at fast idle (approximately 1500 rpm). The voltmeter should show 13-14 V.

5. Then, without reducing the engine speed, turn on the maximum number of electrical consumers (rear window heating, heater blower, etc.). The voltage should be maintained at 13-14 V. Increase the engine speed slightly if necessary to maintain the voltage.

6. If the generator output voltage drops significantly or becomes zero, check the brushes. If the brushes are in good condition, contact a specialist.

7. Sometimes a situation may arise when the generator output voltage is excessively high. A characteristic sign of this is the constant burning out of lamps; significant difference in brightness of lights, changing with engine speed; overheating of the generator and battery, possibly with the formation of vapors. Almost always this occurs due to a defective voltage regulator.