Symptoms of a Bad Voltage Regulator

Symptoms of a Bad Voltage Regulator – The voltage regulator is one of the key components that make up the car’s charging system.

It monitors and maintains the flow of electrical current to the car’s battery and other electrical components in the car. Put simply, it regulates the electrical voltage.

Without the voltage regulator, most electrical components can blow up because the current coming in is raw without any form of regulation.

Just like any other component of your car, the voltage regulator gets damaged or can wear out over time. When it does, it begins to show some signs which will affect the general performance of the car.

Here, we will look at some of the signs and other important things you need to know about your car’s voltage regulator.

What is a Voltage Regulator and How Does it Work?

The voltage regulator is a component that controls the voltage released by the alternator when it charges the battery.

The work of the voltage regulator is to maintain a consistent voltage output for the efficient and optimal performance of the car. It ensures the voltage remains between 13.5 and 14.5 volts to safeguard the car’s electrical components.

The voltage regulator ensures the battery isn’t undercharged or overcharged, which in either case will damage the battery. The unit begins to work once you turn on your car because, at this time, the alternator is already sending an electrical current to the battery.

As the engine runs, a drive belt inside the alternator spins the rotor. This activity electrifies the field coil and generates the required voltage to charge the battery. Before this current gets to the battery, it passes through the regulator.

The regulator has diodes and transistors in it which turns the alternator on and off as voltage output fluctuates. The field coil in the alternator turns as fast as 2,000 rev per second and it is connected to the regulator.

The movement of the field coil opens and closes the connection in the voltage regulator. When the voltage output is low, like below 13.5 volts, the circuit closes, and this action causes the alternator to turn on and increase the supply of power to the battery.

When the battery is fully charged at 14.5 volts, the alternator closes and restricts the magnetic field coil from charging the battery to prevent overcharging and subsequent damage.

Function of the Voltage Regulator

The basic and most common function of the voltage regulator is to monitor and control the alternator’s current output to your vehicle’s battery.

The voltage regulator protects your battery from potential damage because without it, the alternator can release a very high current or too low current and either can weaken the battery’s life or damage it.

The voltage regulator in your car ensures that the amount of electric voltage generated by the battery is constant by monitoring when the battery gets too low or very high. This is done through the momentary closing and opening of some connections in the regulator as required.

Where is the Voltage Regulator Located?

The voltage regulator is usually located inside or at the back of the alternator. Depending on the make of your vehicle and the type of alternator, the position of the voltage regulator can vary in your vehicle.

Some manufacturers place the regulator in easily accessible locations in the alternator while others may mount it in hidden places.  Notwithstanding, the regulator is usually located inside, on the back, or somewhere very close to the alternator, and in some modern vehicles, it is incorporated into the engine control module.

Symptoms of a Bad Voltage Regulator

Excess voltage in the battery

A faulty voltage regulator lacks the ability to control the current that is being sent from the alternator to the battery.

A fully charged and healthy battery is supposed to read between 12.6 volts to 14.7 volts and anything above this is an excess voltage that can cause your battery to explode or crack.

The presence of excess voltage in your battery is a clear symptom of a faulty voltage regulator.

A dead battery

A bad voltage regulator will always cause your battery to die.

If your battery is getting too much power because the voltage regulator is not controlling the output from the alternator, then the excessive voltage will blow up your battery.

On the other hand, if the battery is not receiving adequate voltage due to a bad regulator, the battery will die off.

Dimming vehicle lights

If your voltage regulator is faulty, you will notice that some lights in your car like the headlights and interior lights become dim or begin to flicker.

This can happen because the power output to the battery could be too low and not regulated.

Check engine light or battery warning light comes on

Several engine-related issues could cause the check engine light to come on and one of them is a bad voltage regulator.

If the voltage regulator is causing your battery to overcharge or not charge properly, this will trigger the illumination of the check engine light or battery light.

Poor overall performance of the vehicle

Many components of your car rely on the electrical current from the battery to perform well.

For instance, the spark plugs require some current to ignite, and the fuel pump, sensors, electronic throttle control, and ignition switch all require power from the battery to work.

Thus, in a situation where the voltage regulator is faulty and voltage output is too low, these components will not function as usual. You will experience problems such as misfiring, rough idling, poor acceleration, stalling, or sputtering.

Inaccurate voltage reading

A bad voltage regulator will give an inaccurate reading on the gauge when tested. The numbers displayed on the gauge will be changing inconsistently.

Inconsistent operation of electrical components

A faulty voltage regulator will affect the operation of the electrical components of your car.

The radio, dashboard light, fuel pump, and instrument cluster will be working inconsistently, and this is not good, as several components that ensure the safety and optimal performance of your car are affected.

The instrument cluster includes components such as the speedometer, tachometer, warning lights, and fuel gauge.

Car loses power while driving

Your car needs a stable voltage supply to run and if this is not available, it can lose power while driving.

The voltage regulator ensures that the alternator is sending the required amount of power to the battery and a faulty regulator will fail in this task.

Causes of Voltage Regulator Failure

Apart from the voltage regulator wearing out or failing due to prolonged use, other factors can cause this component to fail.

Such factors include:

  • Corroded battery terminals.
  • A loose ground wire.
  • Faulty battery connection.
  • Overheating electrical components.
  • A bad battery or alternator.

How to test Voltage Regulator Output

Driving with a bad voltage regulator can be dangerous in a way. As such it is important to get it fixed ASAP!

When you notice any of the symptoms listed earlier but you are not certain it is your voltage regulator, you can conduct a quick test to confirm.

Here are the steps you can take to test the voltage regulator of your car.

Step one: Inspect other components like the battery and alternator to ensure they are not faulty. You can check the battery for corrosion, loose terminals, and leakage. Also, ensure the ground connections are still intact and the serpentine belt is working well.

Step Two: While doing this, ensure your car is in a neutral or park position. If the components inspected earlier are in a good condition, get set to test the voltage regulator with a digital multimeter. A multimeter is easy to use, accessible, and a less expensive diagnostic tool. It can cost between $14 to $100.

Step three: Set the multimeter to “DC voltage” and choose 20 volts on the scale. If you have any difficulties doing this, use the service manual that came with the multimeter as a guide.

Step four: Connect the multimeter’s red lead to your battery’s positive (+) terminal and the black lead to the negative (-) terminal. Get someone to help start your car. Let the car run at 1500 RPM.

Step five: When the engine is off, a healthy battery should be reading 12.4 or 12.6 volts on the multimeter. As you’ve turned on your car, the reading should increase by 2 volts making it 14. 4 or 14.6 volts.

Step six: Monitor the digital multimeter. Any reading lesser than 13V or higher than 16V indicates that there is a problem with your voltage regulator. A reading that is less than 13 volts means that your battery is weak and should be replaced.

Any voltage reading higher than 14 volts shows that the regulator is faulty and is unable to control the flow of current to the battery. If the multimeter does not give any reading, it means that the batteries are dead or there is a wrong connection.

Voltage Regulator Replacement Cost

The cost of replacing a voltage regulator is relatively cheap, and you must replace it at once. If ignored, it can cause damage to other components of your car.

The cost of a voltage regulator is between $20 to $150 depending on the brand and quality you choose to buy. You might choose to buy OEM specifications or aftermarket products which will differ in prices.

Labor will cost another $50 to $200 making it a total of $70 to $400 for parts and labor. In some vehicles, a faulty regulator might require you to replace the entire alternator which costs between $250 to $600 with labor inclusive.

Final Thoughts

The voltage regulator is one of the vital components that make up your car’s charging system. Other components are the alternator and battery. Without the voltage regulator, several components in your car might fail, which shows how important the regulator is.

After some period of usage, the regulator may develop faults and start showing some symptoms of failure. When this happens, it is important to test it first because components like the alternator and battery will exhibit similar symptoms if they are faulty.

Frequently Asked Questions

How do you know if your voltage regulator is going bad?

When your voltage regulator is failing, it will begin to show some noticeable signs. As discussed earlier in the article, some of these signs are inaccurate voltage reading, flickering, or dimming lights, dead battery, loss of power, check engine light or battery light comes on, and excessive or insufficient voltage in the battery.

What happens when the voltage regulator goes bad?

When the voltage regulator goes bad, the overall performance of your vehicle will be affected. The instrument cluster which encompasses components like the speedometer, fuel gauge, tachometer, and warning lights will not function properly. Other electrical components like the radio, headlights, security alarm, and ignition system will also be affected.

How do you test the voltage regulator on a car?

When you notice problems with your car, especially with the electrical components, the voltage regulator is one thing that should come to your mind. Testing the voltage regulator is an easy process as explained earlier in this article. What will be required is a digital multimeter and an assistant to help start the vehicle while you are carrying out the test.

Is it the alternator or voltage regulator?

A faulty alternator and voltage regulator will display similar symptoms. Both components can cause your vehicle lights to dim or flicker, loss of power, a dead battery, check engine light illumination, and general poor performance of your vehicle. To know if the problem is with the alternator or voltage regulator, the best thing to do is to carry out a test on each of the components.

How do you troubleshoot a voltage regulator?

To troubleshoot a bad voltage regulator, you need to have the component tested with a multimeter and then read the output. If the voltage reading is over 14.5, it means the voltage regulator is bad and you should take the next step to replace it.