Picture this: It’s early morning, you’ve finished getting ready for work, and you’re heading to your car.

When you put the key in the ignition and turn it, it doesn’t seem to want to start.

Should you call the office to let them know you might be late?

You decide to try one more time, and luckily after a few seconds, it works again.

The weather is a bit chilly, so you decide to turn on the heater, when all of a sudden, the lights flicker and dim. Ok, that’s weird!

As you navigate out of the driveway, you notice a slight hum coming from behind the dash. Then out of nowhere the battery indicator light appears.

Sounds like you might have a problem with your alternator. If you didn’t know, an alternator is responsible for supplying energy to your car. It ensures that items like heating, power steering, and lights have enough power to function.

How much does an alternator repair cost?

It depends if a repair is possible. If not, you’ll need to replace it, which can cost anywhere from $500 to $1,000 (including parts and labor). Otherwise, for something as simple as replacing the alternator belt, expect to pay $100-$150 (not including diagnostics).

Fortunately, in this guide, we will cover this in more detail. We’ll start by going over how an alternator works.

Then we’ll look at some of the most common symptoms that suggest there might be a problem, as well as how to test it yourself at home. Lastly, we will go over the exact costs associated with alternator repairs.

First let’s write down the essentials.
How an alternator works

Simply put, an alternator converts mechanical energy, which your engine produces, into electrical energy.

Components such as air conditioning, power steering, power windows, and radio cannot be powered by mechanical power. Instead, they need electricity, which is why the alternator is crucial.

You may think your battery handles this, but really, it’s just in charge of getting your car to start in the first place. This means that the battery starts the engine and the alternator keeps it running.

The main components of an alternator include the following:
rotor and stator

The rotor and stator run via a belt connected to your crankshaft. As the crankshaft turns, it causes the rotor to turn inside the stator. This creates a magnetic field which results in an electric current.
Diode/Rectifier Assembly

The diode array receives that electricity and converts it from AC (alternating current) to DC (direct current). It then heads outwards to power the various components of your vehicle.

Voltage regulator

You can think of the voltage regulator basically as a surge protector for the alternator, controlling the amount of power it puts out. If too much electricity is sent, it can damage different components. However, if there is not enough, they will not be able to operate.

If any of these parts have a problem, it will compromise your alternator’s ability to continue to function.

This means that your car will have trouble starting because the battery is not charged. Not only that, but your electrical components won’t receive the power they need to function.

Now that you understand the basics of how an alternator does what it does. Let’s look at some symptoms that suggest you’re having trouble.
Symptoms of a faulty alternator
Your car has trouble starting

As we mentioned earlier, the battery is responsible for starting the engine in the first place, and the alternator keeps it running.

However, the alternator also recharges the battery, preventing it from going flat.

If you notice a clicking sound after turning the key, you need to determine which one is faulty. Fortunately, we will discuss how to do it in the next section.
Problems with electrical components

Remember, the alternator has an important job; powers all electrical components in your vehicle.

For this reason, if there is a problem with it, you will not be able to continue doing it.

Watch for signs that suggest you’re struggling to keep up.

Some of these include power windows going up or down more slowly than normal or dimming or flickering headlights or dash lights.

Fixing a faulty alternator early, at the first signs of a problem, ensures things don’t stop working altogether.

Whining or growling sounds

As stated above, your alternator is powered by a belt that is connected to the crankshaft. If you notice a whining or growling sound coming from under the hood, it indicates that there might be a problem with the system. These include damaged or misaligned belts or worn bearings.

Indicator light comes on

One of the most obvious signs of a problem with your charging system is if a battery-shaped indicator light comes on.

While it doesn’t necessarily point to the alternator, it does suggest it.

The first step when this happens is to determine where the problem is coming from, whether it is the battery or the alternator.

Speaking of diagnosing the cause. Let’s see how to test both the alternator and the battery for problems. This is crucial to know, as replacing a battery costs significantly less than alternator repairs.
How to test if an alternator is working properly

For any of these tests, you’ll first need to have a multimeter, which is used to measure voltage, current, and resistance. These can cost anywhere from $15 for a basic multimeter to as much as $100 for one with more features.

For this test, an entry level unit will suffice.
test the battery

A multimeter will have two probes, one red and one black.

Start by connecting the red side to the positive terminal of the battery and the black side to the negative terminal (they will be marked with a plus or minus).

12.6 V is the magic number, which shouldn’t drop much below this range.

Any value below 12.2 means that the battery is only half charged. If it’s too high then there is a problem that can lead to a burnt alternator or battery.

If it is low, unhook the car battery and connect it to a charger. Once full, unplug it from the charger and let it sit overnight. Test it again in the morning, and if it’s still low, you have a bad battery.
test the alternator

First, start your engine since that is when the alternator is running. Next, connect the multimeter leads to your battery, similar to the test above.

You should get a reading between 13.8V and 14.4V.

Anything outside of this range means your alternator is not working properly. In this case, you will need to repair or replace it.

Now that you know how to determine where the problem is coming from. Let’s get to the costs of repairing or replacing an alternator.

Alternator Repair Costs

The typical hourly rate ranges from $50 at a smaller garage to around $100 at a dealership.

Then there is the diagnostic fee of around $80-$120, although some may charge a bit more.

Your options include getting a new alternator or a refurbished or used one. Obviously, a new alternator will cost more, but it will surely last longer.

Fortunately, both a new and a refurbished one must have a warranty.

Used alternators carry more risk and can realistically already have a problem or go out at any time.

Cost for all three options typically ranges from $300-$500. The replacement itself should only take about 2 hours. Add this all up and you have a total cost for an alternator replacement of between $500 and $950.

When it comes to repairs, sometimes all it takes is a new belt or cleaning the connection points.

In this case, you still pay the diagnostic fee and the hourly rate, which should add up to a few hundred euros, depending on the make and model of your car.
to finish

You should now have everything you need to determine if you need an alternator repair or replacement.

Related Posts