The power of a car comes from the engine, and friends who drive are no strangers to car engines. When we suspect that the generator is faulty, we often conduct a preliminary inspection on the car. If it still cannot be solved, we need to remove the engine for a one-step inspection. The tools used for testing can be multimeters (voltage and resistance files), general DC voltmeters, DC ammeters and oscilloscopes, etc., or self-made small test lamps with car bulbs and flashlight bulbs, and can also be tested by changing the working state of the car. The following editor will introduce several methods to detect engine failures.
on-vehicle inspection method
When it is suspected that the generator is not generating electricity, it is not necessary to disassemble the generator and check it on the car to roughly judge whether there is a fault.
1. Multimeter voltage file detection
Turn the multimeter knob to the DC voltage 30V gear (or use a general DC voltmeter to the appropriate gear), connect the red test lead to the generator “armature” connection column, and the black test lead to the housing, so that the engine runs at medium speed or higher, 12V electrical system The standard value of the voltage should be around 14V, and the standard value of the voltage of the 24V electrical system should be around 28V. If the measured voltage is the battery voltage, it indicates that the generator is not generating electricity.
2. External ammeter detection
When there is no ammeter on the dashboard of the car, an external DC ammeter can be used to detect. First remove the generator “armature” connecting pole wire, and then connect the positive pole of the DC ammeter with a range of about 20A to the generator “armature”, and the negative wire to the above-mentioned removed connector. When the engine is running at medium speed or above (no other electrical equipment is used), the ammeter has a 3A~5A charging indication, indicating that the generator is working normally, otherwise the generator will not generate electricity.
3. Light test (car bulb) method
When there is no multimeter and DC meter, you can use a car bulb as a test light to test. Weld the two ends of the bulb with wires of appropriate length, and connect fish clips to both ends. Before testing, remove the wire of the generator “armature” connection post, then clamp one end of the test light to the generator “armature” connection post, and ground the other end. When the engine is running at a medium speed, the test light brightness is explained The generator is working normally, otherwise the generator will not generate electricity.
4. Change the engine speed to observe the brightness of the headlights
After starting the engine, turn on the headlights to gradually increase the engine speed from idle to medium speed. If the brightness of the headlights increases with the increase in speed, it means that the generator is working normally, otherwise it will not generate electricity.
5. Remove the battery and ground the iron to see if the engine is working
When there is no microcomputer-controlled electronic device in the car, this method can be used to detect. Control the engine above the medium speed and remove the battery ground wire (usually disconnect the main control switch on the battery ground wire). If the engine works normally, the generator is generating power, otherwise the generator is faulty.
Detection and judgment of non-disintegration on the car
After removing the generator from the car, you can use the following methods to check to further determine the fault.
1. Flashlight bulb judgment
Connect wires to both ends of the light bulb to make a small test light, which is connected between the generator “armature” and the shell. Use wires to connect the positive and negative poles of the battery (or dry battery of the same voltage) to the two magnetic field terminals “F1” and “F2” of the generator (the internally grounded alternator is connected to the “F” and “ground” terminals ), let the battery excite the generator. Rotate the engine belt pulley quickly by hand, and a small test light indicates that the generator is working normally, otherwise the generator will not generate electricity.
2. Multimeter voltage file judgment
Let the battery excite the generator (the wiring method is the same as the judgment of the hand light bulb), select the multimeter in the DC voltage 3-5V (or the appropriate gear of the general DC voltmeter), and connect the black and red test leads to the “ground” and the generator “electricity” respectively. “Pivot” is connected to the column, turn the belt pulley by hand, the pointer of the multimeter (or DC voltmeter) should swing, otherwise the generator will not generate electricity.
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