Maintenance Tips

how to test car alternator without meter

 All cars are liable in one way or another to break down at any moment without warning, especially if you neglect the appointment of the car’s maintenance such as changing the filters or oil. But often the car breaks down due to a weak battery due to a faulty alternator.

First, let’s say your car broke down and you don’t have tools to test your car, first you should test the alternator in a safe way, such as using a multimeter to test the condition of the car battery to find out why the car broke down or you can use an appropriate check tool for the charging system.

how to test car alternator without meter

Secondly, if your car breaks down in unusual circumstances and you still want to be sure if the alternator is the cause of the car breakdown and the alternator can work normally while you don’t have a multimeter, you can rely on this alternator tester. Here is how to test the generator without a multimeter.

1. Alternator magnetic test

We all know that the alternator works on the basis of electromagnetism, from here we can perform a magnetic test of the alternator to test the alternator without a multimeter. The benefit of this magnetic test is to check the effect of the electromagnet generated by the components of the rotor and the stator inside the generator simultaneously and to shorten the time.

Scientifically, every electric current that flows through the coil, it produces magnetically. It will automatically pull any metal objects close to the magnet to the magnetic source in the alternator, the rotating coil connected to the pulley. In turn, the stator coil is connected to the generator body.

If the magnetic effect does not work inside the generator. In this case, this indicates that the rotating coil or stator coil has broken or prevented electric current from flowing to the generator.

To perform a magnetic test of the alternator, we need some metal objects, such as wrenches or a screwdriver. Attention, if the alternator is a challenge to get inside the engine (eg, if the alternator is under the engine), it is best to skip this test.

This is an AC Alternator Magnetic Tester, do it very carefully when needed only.

a. Magnetic test on generator rotor coil

  1. Set your ignition switch to the on position and do not start the engine, look for the alternator pulley.
  2. Place the metal wrench near the alternator pulley.
  3. If you notice the wrench sticking to the pulley, the electromagnetic from the rotor is working fine.
  4. If the wrench does not stick With the pulley, the rotor coil has fractured and failed to produce an electromagnet.

B. Magnetic test on generator stator coil

  1. Start the engine and let it run until it reaches the rpm.
  2. Look for the alternator. Place the metal wrench close to the generator body.
  3. If you notice the wrench sticking to the alternator, the electromagnetic from the stator coil is working fine.
  4. If the wrench does not stick to the alternator, The stator coil was damaged and failed to produce sufficient electromagnet.

Read also: How to test your alternator: TROUBLESHOOTING

2. Test the generator voltage and current

Our second test on how to test an alternator without a multimeter is to perform an AC voltage and current test. The benefit of this test is to ensure that the alternator is producing sufficient voltage and current to the electrical components of the motor.

The role of the generator while the engine is running is to produce electric currents to power all the electrical parts and to recharge the battery automatically. Suppose that the electric currents do not arrive from the generator to power all the electrical components and are insufficient or weak. In this case, your engine will stop working at any moment.

We all know that most car charging systems use the positive battery as an input for the flow of electric currents until the charging process is completed. That is why you find that the alternator voltage is always higher than the battery voltage. And what we’re doing here is unplugging the positive terminal cable from the battery while the engine is running.

Test the alternator with the battery disconnected?

Here is how to test the alternator by disconnecting the battery with easy steps that everyone can do:

  1. Start the engine and let it run until it reaches the engine rpm.
  2. Turn off all electrical systems in your car (headlight, air conditioner, radio, charger…).
  3. Lift the nut on the positive battery cable.
  4. Gently pull the positive cable from the battery terminal. Hold it tight.
  5. Watch the engine carefully. If it stops, this indicates that the alternator has failed to produce enough electric current for the car.
  6. If the engine does not stop spinning, this indicates that the alternator is working well and is not a cause of the car’s failure.
  7. Immediately stop the engine, then start Gently disconnect the negative battery.
  8. Carefully reconnect the positive battery cable, then do the same steps with the negative cable.

Related Articles

Back to top button