Alternator repair & replacement made easy

A fair price in seconds, mechanics you can trust, next-day service at your door

149000+
Customer Reviews
4.8

Up to 50% cheaper than franchise dealers

Instant fixed price quotes
(no hidden estimates)

Fully vetted & qualified mechanics

1 year parts & repairs warranty

Next day bookings at your home or office

Get your car repaired at your home or office

Expert Mechanics

200+

Total expert alternator repair mechanics

Number of Ratings

3,087

Total number of alternator repair reviews

Average Rating

Average user rating for alternator repair bookings

How does an alternator work?

An alternator is a vital part of your car’s electrical system, acting like a mini power plant under the bonnet. Think of it as the heart of the car’s electrical system, keeping everything powered up while you drive. When your engine is running, the alternator takes over from the battery to supply power to your car’s electrical components, like the headlights, radio, and air conditioning.

Here’s how it works: the alternator is driven by a belt connected to the engine. As the engine runs, it spins the alternator’s pulley. Inside the alternator, a rotor (a rotating magnet) spins inside a coil of wire called the stator. This movement generates an alternating current (AC) through electromagnetic induction.

This AC is then converted into direct current (DC) by the alternator’s rectifier, making it suitable for the car’s battery and electrical system. The voltage regulator ensures the output stays within a safe range to protect the battery and electrical components from overcharging or undercharging.

By continually replenishing the battery and providing power to the car’s electrical systems, the alternator ensures that everything runs smoothly. If the alternator fails, your car’s battery will quickly drain, leading to electrical issues and eventually preventing the car from starting.

What does an alternator replacement job involve?

An alternator replacement job involves several key steps to ensure your car's electrical system functions properly again. Here’s a simplified overview of the process:

  • First, the mechanic raises the car using a lift or jack to gain easier access to the engine bay.
  • The battery is disconnected to prevent any electrical shorts or accidents while working on the alternator.
  • The mechanic then removes any necessary components that obstruct access to the alternator. This can include the belt, brackets, and sometimes other engine components.
  • Next, the wiring connected to the alternator is carefully disconnected. This includes the main power cable and the voltage regulator connector. Mechanic will test the voltage output of the alternator at the battery terminals.
  • The old alternator is then unbolted and removed from the engine.
  • Before installing the new alternator, the mechanic checks the condition of the drive belt and tensioner. If these parts are worn or damaged, they are often replaced at the same time.
  • The new alternator is then positioned and bolted into place. The mechanic ensures that it is aligned properly to the engine.
  • The wiring is reconnected to the new alternator, making sure all connections are secure and free of corrosion.
  • Any components that were removed earlier to access the alternator are reinstalled.
  • Enter the radio code if required and present.
  • The battery is reconnected, and the mechanic starts the car to test the new alternator. They check the voltage output to ensure it is within the correct range and verify that the car's electrical system is functioning properly.

This job requires skill and precision, which is why it’s best done by a professional mechanic.

How do I know whether I need an alternator repair or replacement?

An alternator should generally be replaced as it can’t really be repaired in most cases. Look out for these key signs:

  • If you notice your car’s battery warning light on the dashboard, it might indicate a problem with the alternator. This light often means that the alternator isn’t charging the battery properly and might need attention.

  • If your car’s headlights or interior lights start to dim or flicker, it could mean the alternator is failing to provide consistent power. This is a common sign that the alternator might need repair or replacement.

  • If you hear a whining or grinding noise coming from the engine area, especially when the vehicle is starting, it could be a sign that the alternator’s internal components are wearing out.

  • If your car’s electrical accessories, such as the radio, power windows, or air conditioning, start to work intermittently or stop functioning altogether, the alternator might be the culprit. These issues can indicate that the alternator is not generating enough power.

  • If your battery frequently dies or struggles to hold a charge, it could be due to a failing alternator. While a dead battery can have other causes, it’s often linked to alternator problems.

  • If you smell a burning rubber or electrical odour, it might mean that the alternator is overheating or there’s a wiring issue. This usually means the alternator might need replacement.

  • If your car stalls or has difficulty starting, it could indicate that the alternator isn’t supplying enough power to the ignition system. This is a serious sign that the alternator might need to be replaced.

Can an alternator be repaired?

Whilst it is theoretically possible to do, it would actually work out to be more expensive. Internal alternator parts are not “off the shelf” and would require ordering in and along with the strip down, cleaning and rebuild time, the labour costs would push this above the price of the new alternator. It could also mean that you would be without use of the vehicle for some time. It just isn’t worth it, so at ClickMechanic we do not carry it out.

Should I book an alternator replacement and alternator or a serpentine belt replacement at the same time?

If you’re experiencing issues like dimming lights, a battery warning light on the dashboard, or strange noises from the engine, you probably need an alternator replacement. The alternator is a part that wears out over time, and these signs usually mean it’s time for a new one.

The serpentine belt drives the alternator and other components like the power steering pump and air conditioning compressor. When the alternator is being replaced, the mechanic may inspect the serpentine belt. If it’s in good shape, it can often be reused. However, if it’s cracked, frayed, or showing signs of wear, it should be replaced too.

In general, it is highly recommended to replace the alternator and serpentine belt at the same time if you want to ensure maximum performance and longevity from your new alternator. This way, the cost of labour will be lower since the mechanic is already working on those parts of the car.

Should I book an alternator replacement and battery replacement at the same time?

The alternator and battery work together to power your vehicle's electrical systems. If one is failing, it can affect the other. For instance, a failing alternator can lead to a drained battery, and a weak battery can put extra strain on the alternator.

If the battery is still holding a charge well and isn’t too old, it can often be reused. However, if it’s weak or near the end of its lifespan, it should be replaced too. It can sometimes be challenging to diagnose whether the alternator or battery is the primary issue. Replacing both components can eliminate any uncertainty and provide a fresh start for your vehicle’s electrical system.

In general, it is highly recommended to replace the alternator and battery at the same time if you want to ensure optimal performance and avoid future issues. This way, the cost of labour will be lower since the mechanic is already working on the electrical system.

How much does an alternator replacement cost?

Unfortunately, with alternators, even the dealership cannot be 100% certain what has been fitted to the car until they actually see the unit. One of the reasons for this is that when ordered from new, there is usually a vast range of additional extras that are available. Some of these extras require the vehicle to be built with higher (or even lower!) rating alternators. Optional extras such as heated and electrically adjusted seats for example mean a much higher rating of alternator would have been fitted.

ClickMechanic prices the part on the most widely used version, if your vehicle does not have this fitted, then an additional charge may be required. However, in this scenario, both the mechanic and ClickMechanic will discuss this and the options prior to commencing the actual replacement.

To know more about the cost of alternator replacement, you can use our alternator replacement price estimator tool here.

What does an alternative replacement price/ quote cover?

Unless otherwise stated, a ClickMechanic quote for your alternator to be replaced will cover;

  • The alternator (of the same rating recommended by the manufacturer)
  • Coming to you
  • Fitting of the alternator
  • Coding of the alternator to the vehicle's electrical system (if required)
  • Entering the radio code if required and present
  • Ensuring the electric windows close and open as they should
  • Checking that charging system is working appropriately
  • VAT (if applicable)
  • 12 months parts and labour warranty

Please note that in most cases the mechanic will need to take the old alternator and return it to have the surcharge on the new one reimbursed. Should you wish to keep the old alternator, there may be an additional charge to do so.

Can the alternator be replaced by a mobile mechanic?

Yes, the alternator can be replaced by a mobile mechanic as it is a fairly straightforward job for them. It’s quite common for the battery to also be affected if the alternator is damaged which means going to the garage can be a hassle! Mobile mechanics are equipped with the necessary tools and expertise to perform an alternator replacement at your location, providing convenience and saving you time.

By booking with a mobile mechanic, you can avoid the hassle of towing your vehicle to a shop and enjoy the flexibility of having the repair done at your home or workplace. Mobile mechanics are often cheaper than going to a garage.

Top Mechanics For Alternator Repair & Replacements

67 Reviews

Mobile mechanic in Romsey, 12 years of experience

I started my career in HM Armed forces joining the REME, where I served for 7 years. From there I worked for Mercedes-Benz for 4 years. And now I do all sorts, if it’s got wheels, I can fix it!

127 Reviews

Garage in Wigan, 17 years of experience

I've worked in the motor trade for around 17 years my services include mot's, tyres, brakes, suspension, diagnostic and servicing

59 Reviews

Mobile mechanic in Northolt, London , 18 years of experience

I have 18 years of experience working with all type of motor vehicle as qualified mechanic. WEBSITE ADRESS <a href='https://www.clickmechanic.com/' title='ClickMechanic'><img width='250' src='https://bad...

172 Reviews

Garage in Aylesbury , 25 years of experience

Daniel Auto Services - deal with everything from servicing, brakes and tyres. All round handyman.

8 Reviews

Garage in Blackburn, 9 years of experience

I have worked as an automotive engineer in emirates over 6 years and i always had a passion about cars since i was young and that’s why i have chosen this industry to work because i love playing with cars.i ...

1492 Reviews

Garage in Darwen, 14 years of experience

I started my apprenticeship when I left school at the age of 15. I’ve been fully qualified for 11+ years with NVQ level 1, 2 and 3. I’ve been an MOT tester for 10 years. Here at Jamie’s mobile mechanic w...

72 Reviews

Garage in Brimingham, 5 years of experience

Established 25 April 2024 but with over 5 years experience, JSR Repairs LTD is garage in the West Midlands, specialising in all automotive repairs from services to diagnostics. Always happy to collect and de...

4 Reviews

Garage in Sevenoaks, Weald, 19 years of experience

Here at HJF Autos we are a family run business, we can take care of all vehicle repairs from brake pads to engine rebuilds. We have a full range of diagnostic equipment to diagnose all UK, European, Asian an...

112 Reviews

Garage in Sheffield, 7 years of experience

Your car is in good hands at Automotive Repairs. We have a wide rage of services that we offer to keep your car safe and on the road. Reliability and honest is our only approach to our customers while also b...

204 Reviews

Garage in Leicester, 15 years of experience

At J.J. Auto Repair we always aim to be helpful and friendly. We offer a range of services including, Mobile mechanic, Diagnostics, Full service, Multimedia system fitting, and more...

59 Reviews

Garage in Sheffield, 13 years of experience

3 years learning roadside repairs 5 years across different garages 3 years self employed 1 year managing a garage 1 year specialising in dpfs and gpfs.

92 Reviews

Garage in Barry, 7 years of experience

Mobile mechanic with specialist knowledge of 4x4 & Diesel Vehicles based in South Wales. I take pride in all the work I complete and treat every Vehicle like my own. I only ever use genuine or OE spec parts ...

12 Reviews

Garage in Slough, 12 years of experience

We provide various different types of services whether it be as simple as a service or more complex fixes such as timing chains or engine rebuilds. We take huge pride in our work and make sure it is done to ...

208 Reviews

Garage in Thornton Heath, 7 years of experience

Welcome to AUTO PRO, where automotive excellence meets customer satisfaction! With over 7 years of hands-on experience in the auto industry, we take pride in being your trusted partner for all things automot...

40 Reviews

Garage in Gravesend , 20 years of experience

20 years experience in mechanical work with loads of qualifications work for bmw and Ford garage

Frequently asked questions about alternator repair & replacements

Read our answers to questions about alternator repair costs, symptoms and more.

What does an alternator do?

The alternator is an electrical generator driven by a belt off the engine to charge the battery of the car. It is vital that the alternator works effectively, seeing that the battery provides electricity to a range of components.

What does an alternator replacement involve?

  • Mechanic will inspect the car's battery charging system.
  • Mechanic will inspect the alternator's ancillaries (drive belt, cables etc.)
  • Mechanic will test the voltage output of the alternator.
  • If necessary, the mechanic will replace the alternator.
  • Mechanic will advise if any other parts of the electric system need to be replaced.
  • Mechanic will test the charging system and will test drive the car.

Can I replace my alternator myself?

Unless you are a qualified mechanic with the required skills, training and equipment to do the job, we strongly recommend an alternator replacement is only carried out by a professional mechanic. ClickMechanic can help get you a vetted and local mechanic to carry out the work. Just enter your postcode and your car's registration number at the top of this page and select the work needed to get an instant fixed price up front.

What are the symptoms of a bad alternator?

  • When the battery warning light on the car's dashboard has lit up.
  • When the battery is not being recharged

How long does it take a mechanic to replace an alternator?

On average, alternator replacement times can range from 1 hour to 2.5 hours with an average of just over 1 hour. The time that the job takes will depend on a number of factors, like your vehicle's make and model, year, as well as other factors. Select your car at the top of this page for information on job time and cost for your vehicle through ClickMechanic.

How often should I replace an alternator?

Generally alternators only need to be replaced if there is an issue with them. Should you experience any problems like those listed it is important to have the battery charging system inspected and, if necessary, have the alternator replaced.

As the demand for more and more electrical equipment and devices on modern vehicles increases, the demand on the alternator is increased. Therefore whilst the units themselves have improved dramatically in design and reliability, this is outweighed by the increased reliance on it. So, alternator replacement is a frequent repair on most vehicles at some point.

What are the signs of a bad alternator?

If the battery light remains on with the ignition (and does not go out once the charging is in operation), or comes on with the engine running then there is an issue with the alternator generating power and the battery will not be recharged. It is important to get a professional mechanic to check the issue as soon as possible.

How can I extend the lifetime of my alternator?

Because it is not possible to turn the alternator off and it will therefore always be turning when the engine is running, there is little you can do to prevent wear and tear. Obviously as an electrical device, they do not like water, so avoiding flooding is important!

Can you drive with a bad alternator?

If you have a bad alternator then technically your car will likely still drive, but it is advisable to get help from a professional mechanic before running the vehicle again. Not addressing issues with the alternator will lead to your battery not getting charged and a flat battery, ultimately leading to your vehicle not being able to start again.

Should you replace battery with alternator?

Whether you will need to replace the battery with the alternator ultimately depends on the battery's condition. If you're not sure if it needs replacing we'd recommend booking with a professional mechanic to check the issue and advise on next steps.

How long will a battery last with a bad alternator?

There are a number of factors that would determine how long a battery would last if the alternator is bad and not charging it correctly. Primarily it will depend on how much energy your car consumes and the condition of the battery.

Is a faulty alternator an MOT failure?

No, a car will not fail its MOT on an alternator issue itself. The alternator is not checked as part of the MOT, but a garage may flag it as something to address outside of an MOT to help ensure your vehicle will be able to charge its battery as intended.

Can a bad or faulty alternator affect a new battery?

A bad alternator can damage a new battery if the battery is not receiving the proper charging voltage. While it may not completely destroy it, a faulty alternator can cause a new battery to drain more quickly than it should.

Can a car work without an alternator?

It is possible for a car to run without an alternator, but it will not run for very long. It is likely that the battery will eventually die, and the car will eventually come to a halt.

Can an alternator fail suddenly?

Alternators can fail suddenly, but more often than not they will slowly lose their ability to charge the battery and eventually die. So even if it fails while driving, you may still be able to drive the car a few miles before the car comes to a complete stop.

How do I check if my car alternator is working properly?

The easiest way to check if your alternator is working is to start the car and let it idle. Then, turn on all of the car's accessories one at a time. If the car's battery dies while the accessories are on, then the alternator is not working.

Additionally, the battery should be tested for voltage. If the battery is low, the alternator may not be charging the battery. Depending on the electrical system, a voltmeter reading in the 13.8 to 15.3 volt range with the engine running, lights and accessories off, generally indicates that the alternator is working as it should be.

Can I jumpstart a car with a bad or faulty alternator?

If the battery is not dead, then yes, you can jumpstart a car with a bad alternator, but it will only run for a short period of time before the battery is drained again.

What happens when the car alternator fails while I am driving?

If your alternator dies while driving, your car will eventually lose power and come to a stop. You may notice the first signs of a dying alternator with dimmed interior lights and warning lights on the dashboard. The best thing to do in this case is find a safe place to stop and call for professional help.

How do I fix a bad alternator?

In most cases the alternator would be replaced if it bad or faulty. Alternators can be refurbished but often getting a new one fitted is more cost-effective. An alternator is an electrical component that is key to supplying power to your car so fixing it is a job best left to qualified technicians.

How much does an alternator replacement cost?

On average, a typical alternator repair costs £250, with prices ranging from £150 to £400. Ultimately, cost depends on your location, car and what parts your car's manufacturer recommends using for the replacement. Find out what you could save by having your alternator replaced by ClickMechanic by selecting your car at the top of this page!

Check out the ClickMechanic price for an alternator repair. See the averages for different makes below. We consolidate industry standard data with millions of data points to give you the most accurate price. These estimates may include Alternator.

Estimates on average repair costs, such as the above results for an alternator repair, are based on ClickMechanic's quote data which combines multiple third-party sources. Actual costs may vary. We provide estimates on average repair costs for information only and accept no liability for any inaccuracies or errors. If you think an estimate is incorrect, please contact us to let us know.

Book a trusted mechanic today

Get an instant quote, then book a vetted mechanic to fix your car at your home or office.

  • Vetted mechanics
  • Save up to 50%
  • Fast online booking

Book repairs for hundreds of makes and faults