How to Test Alternator with Screwdriver

Does your automobile not crank up in the morning because the battery drains rapidly if you leave it parked? These are indications that your Alternator may malfunction and need to be replaced. Diagnosing the issue can be a complex endeavour, but this test takes only a few hours and a few simple tools and supplies. Here’s the best guide to testing your Alternator.

The Alternator is the battery-charging device for your vehicle. It generates electricity to charge the battery and provides power to all your accessories in the car. The Alternator should be tested periodically because it is crucial for your vehicle’s electrical wiring.

If you really want to know how to test your Alternator with a screwdriver, check out this simple step-by-step procedure! You can complete it in roughly 10 minutes if you have all the equipment required for this undertaking.


What is The Alternator Field Current?

A straightforward way to know how to test your Alternator through a screwdriver is to apply a screwdriver to the Alternator to see if it produces a magnetic field. If there is one, your Alternator is in working condition. So why is the existence of this magnetic field meaningful?

As the alternator pulley spins, the alternator rotor spins. The armature of the rotor contains conductor wire wound around a ferrous core made of iron. Current flowing through the conductor wire produces the field current discussed earlier. Field current intensifying with the amount, strength, and duration of the Alternator’s operation creates a stronger magnetic field.

Therefore, as you will see later on, we will analyze the strength of the current to see if there is a magnetic field and if that’s the case. If there is such kind of a magnetic field, this signifies a current that is strong enough to operate the Alternator. Thus we are using it.

The voltage regulator helps you to charge the battery by supplying the cells with a steady voltage. Using a switching regulator, the field current is altered to create a constant voltage at the battery terminals. A rectifier/diode bridge is combined with a switching regulator to convert AC voltage into DC voltage.

How to Test Alternator with Screwdriver


Converting a rotating motor into a high-frequency current in the system equates to the amount of field current reaching the alternator rotor and the resulting magnetic field. The power gained by the Alternator is then used to charge the battery.

The battery is connected to the regulator so that the battery receives the exact amount of voltage it needs to have. The regulator is educated about the battery’s voltage and sends the necessary information about how much voltage the regulator will be responsible for the rotor.

If the battery voltage drops, the regulator should increase the field current being sent through the rotor, which subsequently causes the field current to become stronger. As a result, the Alternator’s output voltage should also increase in response. Conversely, if the battery voltage rises, less field current reaches the rotor, which weakens the strength of the magnetic field and affects the alternator current.

One note is that the Alternator field’s current level is substantially lower. The current level depends on the amperage at which the Alternator operates. For example, Huashan can use 40 kW to 120 kW as high-amp alternators can generate from 200 kW to 300 kW (70 kW alternator can work between 7 and 20 kW).

With the help of the screwdriver, you can test the Alternator’s current in the field yourself. But, first, let’s learn why we must observe the alternators’ field current.

You’ll need a screwdriver, electrical tape, wire connectors, and distilled water.

How Alternator of vehicle works

A rotary device that converts electrical energy to mechanical energy, and thus produces alternating current (AC) electricity, is an alternator. It is used to power various electrical systems of automobiles, boats, planes, motorhomes, trucks, and trains.

The Alternator is what connects the automobile’s battery and engine to generate electricity for the vehicle’s needs and gadgets. It increases voltage and provides a long current stream to the vehicle’s lighting system, radio, and other accessories.

If you have a light switch, you may hear the sound it makes when you turn it on as your Alternator begins to build electricity. It’s the exact mechanism that creates it, just smaller.

What happens If Alternator is not Working

Your vehicle’s Alternator is critical. A costly repair bill could be incurred without your Alternator working adequately.

If your vehicle’s Alternator fails, it may result in a variety of problems. For example, if your Alternator stops functioning, the battery fills the charge and eventually dies, leaving you stranded at the side of a road. It’s therefore essential to have your Alternator evaluated regularly.

So, to spend less on the expensive repair job, you need to be able to test your Alternator.

How to test Alternator with Screwdriver

Testing your Alternator with a screwdriver is a simple process that you can efficiently perform at home. You don’t need to take your car to the mechanic or the auto repair shop. However, the process involves several basic steps, so before you begin the procedure, ensure the vehicle is turned off and parked on level ground where it won t roll off.

Framework technicians generally use a screwdriver to verify their framework partially.

Insert Key Into Ignition. Insert Your key into the ignition without preparation; do not worry about any noise your car may make once it starts. To start the car, just press the key and leave it inside.

2: Open Your Car Hood.

You must uncover the latch beneath your vehicle’s hood to access your Alternator and lift it. This is how you will open the hood of your for alternator testing.

3: Find The Alternator Off The Car

A coil-shaped transformer with a belt adjoins other parts of the Alternator. Depending on your car model, you may also see additional parallel belts, pulleys, or gears near the Alternator. The significant component of this equipment is plugged into an electric socket through singular cable television. Ask for assistance or contact the manufacturer if you can’t identify it.

4: Put The Screwdriver Near The Alternator

Now that you know where the Alternator is located within your engine use your screwdriver to inspect it. Put the screwdriver near the Alternator when your key is in the ignition.

You have to possess enough screwdrivers to ensure you can access it, but not so far that you’ll damage any other machine component.

You should touch the tip of your screwdriver blade to the alternator nuts near the pulley, and the magnetism will draw the screwdriver.

If you don t notice an electromagnetic field in your resting place, your Alternator is working, and you don’t have to worry about it. But if you do not feel a strong magnetic field, you might have trouble with your Alternator.

If you cannot point out an electromagnetic field anywhere on your body, your Alternator usually works, and you will not need to worry about it. However, you might have difficulty troubleshooting your Alternator if you do not feel a strong magnetic field.


Some Signs of Alternator Malfunctioning

If you have ever been run out of battery in your car, then you know the importance of this component. The Alternator is somehow responsible for charging the battery. Without it, your vehicle’s battery would die sooner than usual, resulting in significant damage.

Being concerned about whether your Alternator is working is typical. However, there are several signs that your Alternator may be malfunctioning.

  1. The systems that provide headlights, dashboard lights, or other electrical systems will flicker.
  2. The battery isn’t holding a charge and needs to be charged more often than usual.
  3. The energy will often bog down if the engine does not receive sufficient power.
  4. The air conditioner’s effectiveness falters or picks up at less than optimal rates.
  5. The vehicle sometimes stalls or makes an unusual buzzing or other sounds such as clicking, whirring, or humming when the engine is in operation.
  6. The battery warning light will come on and stay illuminated if the Alternator in a car or truck is not functioning well.

If you experience these symptoms with a faulty alternator, then it’s of paramount importance to seek a professional opinion before your Alternator completely fails.

Will a Car Run With a Bad Alternator?

The car’s engine draws power steadily even after the battery is drained, but the vehicle may shut down sooner or later. Other parts also draw power, such as headlights, taillights, interior lights, and the engine control unit (ECU).

In short, the answer is that nobody ever intended an alternator or car with no electrical power to get any of the necessary components to function to make it run. If this electrical malfunction occurs while you’re on the road for a long drive, your safety may decline.

You ought to frequently test the Alternator and the battery in your vehicle at home. In addition, carry out your upkeep checks regularly to know the best methods of preventative vehicle maintenance.

Protecting Your Alternator

As alternators are among the durability of the car’s components, you need to examine and maintain them routinely. You should pay special attention to your Alternator during scheduled checks, so any changes can be pinpointed quickly. If your Alternator ever begins acting up, your vehicle will surely come to a sudden stop in a short period.

Protecting your Alternator is all about keeping your engine safe, as they are close. This involves ensuring your engine’s protective cover remains intact and replacing it. 

If there is damage, prevent any stray projectiles from the road from reaching your Alternator and engine, and repair any oil leak immediately as it may cause damage to your Alternator.

If you decide to wash the exterior engine compartment, ensure the cover of the channel box is well-covered to protect it from the rain and cleaner.

Final Words!

We hope this article will help you attain the desired result with your Alternator and encourage you to consult your mechanic for more tips and solutions. As stated previously, there are several other means to evaluate your engine alternator, and you can ask your automobile technician to inspect your motor vehicle. However, by using this simple approach, you can get a good idea of whether or not the Alternator is running correctly.

Thanks a lot for taking the time to read our article. We fervently hope that it makes the light in your Alternator easy to take care of in case there is anything else you would like to know. Please let us know what you think so that we may better serve future readers.

If you really liked this article, remember to share it with others. Good luck! Cheers!


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