How to Test When the Generator is Not Generating Electricity?
2 Answers
Steps to test a car generator that is not generating electricity: 1. Rotate the multimeter knob to DC voltage 30V. 2. Connect the red probe to the generator's "armature" terminal and the black probe to the casing. 3. Run the engine at medium speed or higher. The standard voltage value for a 12V electrical system should be around 14V, and for a 24V electrical system, it should be around 28V. 4. If the measured voltage is the same as the battery voltage, it indicates that the generator is not generating electricity. The following are the reasons why a car generator may not generate electricity: 1. The diodes are broken and cannot perform rectification. 2. The brush is stuck in the brush holder, causing the generator to fail to generate electricity due to lack of excitation. 3. The rotor's field coil is not energized. 4. Short circuit or grounding between the stator coils. 5. The rotor's claw poles are loose.
If I find that the car's alternator isn't generating electricity, I'll first check the battery warning light on the dashboard—if it's on, it suggests the alternator isn't working. Then, I'll use a multimeter to measure the battery voltage. When the engine is running, it should be around 13-14 volts. If it's below 12.6 volts or doesn't change, there's definitely a charging issue. I'll inspect the belt for looseness or damage—a quick touch can tell if it still has elasticity. Next, I'll check the wiring connections for corrosion or looseness by gently tugging to test stability. Don’t forget to examine the relevant fuses in the fuse box—if blown, replace them. Also, inspect the alternator components like the rectifier for aging, but if you're unsure, don’t force disassembly. Instead, drive to a professional shop for a quick scan with a diagnostic tool—it saves time, effort, and ensures safety.
