Most of us have experienced that dreaded feeling when the car won’t start. It can be daunting, especially if you don’t know what the issue is. Many problems can be traced to either the alternator or the battery – but how can you tell what is causing the problem?



Your alternator and your battery are essential parts of your car. If your car won’t start at all, it is likely that your battery is dead. If your car starts but dies shortly afterwards, it is likely to be an issue with your alternator.

There are several reasons why you may have an issue with either – from loose belts, extreme temperatures, worn-out components, and under or over use. It is important to distinguish which is causing the issue so you can take the appropriate steps towards fixing it.


How Do I Tell If It Is My Alternator Or My Battery?

An easy way to tell whether it is the alternator or the battery that is causing an issue is to pay attention to when you start the car. If the car won’t start at all, the battery is dead. If the car starts but dies after it runs, there is an issue with the alternator. If the car runs, but won’t hold a charge, it could be either and needs some more investigation.


What Are The Common Battery Problems?


Not Switching Off Electrical Items

One of the simplest causes of battery problems is human forgetfulness. Some cars’ headlights or interior lights don’t switch off with the engine, so if they get left on by accident the battery will run until it is flat.

Always ensure everything is turned off to ensure you won’t be returning to a flat battery next time you need to drive.


Cold Weather

Batteries and cold weather do not mix well. The chemical reaction that happens within batteries to get things working can’t happen in freezing temperatures, so if it is particularly cold outside, you may have to allow the battery to warm up before you can use your car.

Try charging it to get things warmed up. If the battery dies completely, you’ll have to jump-start it. You can learn how to do this in this article.


Frequent Short Journeys

Constantly turning off and restarting the engine is a sure way to drain your battery. Firing it up takes more power, so doing it a lot will run the battery flat.

If you drive infrequently, try and keep it running for a bit longer every now and again, and don’t turn your engine off at traffic lights.


Loose Connections

If the car’s battery isn’t connected properly, you could be running the risk of damaging the car and the battery. You should regularly be checking everything is tightly screwed in – loose connections can cause sparks, which may result in fires.

Always ensure the engine is cool before you touch anything under the bonnet to avoid burns – your engine bay gets really hot!


Excessive Loading

All batteries are only capable of powering so much. If you are using your car’s battery to constantly power things such as a portable mini fridge or DVD players on a road trip, you’ll be putting excessive strain on your battery.

If this is something you do often, consider buying a more powerful battery, and ensure you’re always fully charged before a long journey.


What Are The Common Alternator Problems?

Incorrect Pulley Alignment

Incorrect pulley alignment can cause premature belt wear or overheating, two issues that will stop your alternator from working. Since the pulley is the primary point of contact between the belt and the alternator, it is essential that the alignment is correct to keep everything running smoothly.


Worn Bearings

Your alternator uses roller bearings to ensure your alternator keeps moving as they should. As they move constantly, friction can cause the alternator to wear them down.

If the bearings are not replaced when they need to be, vibrations may occur, causing issues in the alternator.


Worn Belt

Over time, the belt in your alternator will become worn simply from use. It may come loose and disconnected, which will result in a faulty alternator. Listen out for slapping noises – you’ll also be able to see straight away if your belt needs changing or has disconnected.


Broken Voltage Regulator

Your alternator has a regular voltage that converts the engine's AC current to a DC current. If the regulator is broken, this conversion will be unsuccessful – the alternator will continue to work, however, the power output is non-existent. You will need to have the voltage regulator replaced.


Loose Wiring

Your alternator is connected to the battery with wires. If the wires are damaged, the power from the alternator will fail to reach the battery, meaning that it will not work.



Overheating can be a serious problem with your alternator. Many of the issues listed here can cause it, or simply being overworked can result in your alternator getting too hot.

If your alternator is overheating, you will be able to smell burning – and should have it looked at straight away to avoid any dangerous situations or irreparable damage.


What Should I Look Out For?

Sometimes you’ll be able to spot warning signs of a dying alternator or battery before you get stuck with a car that won’t start. Watch out for dim headlights and interior lights, as this can indicate an issue with your battery. A burning smell may indicate an issue with your alternator belt or damage to your wires.

If your alternator belt has come loose, you will be able to hear a squealing noise. Pay attention to your dashboard lights, too – of course, the battery warning light, but if all of your dashboard lights are flickering or dimming, your alternator may be struggling to supply power.


How Do I Check My Alternator?

If you have diagnosed your issue as one with the alternator, there is a way of checking it with a device called a voltmeter. This device reads the voltage of your battery and will be able to indicate if your alternator is working as it should.

You can buy a voltmeter from Amazon, or any good automotive shop. Ensure the battery is fully charged before you conduct the test – the voltmeter should read between 12.5 and 12.8 with the engine switched off. Then start the engine and read the results – if your alternator is working correctly, you should see higher readings. If the readings remain in the 12-volt range, you have an issue with your alternator, and will need to have it looked at by a professional.



What Does An Alternator Do?

What Does A Battery Do?

How Long Can A Car Run With a Faulty Alternator?

How Long Will A Car Run For With A Bad Battery?

How Often Should I Replace My Car Battery?