Do you have to replace the alternator when replacing the battery?

It can ruin your day when your car doesn’t start. Could it be the alternator or the battery? Do you have to replace the alternator when replacing the battery? The answer is no. As long as one or the other is bad then you are fine to just replace just the one. Although you should first determine what is causing the issue.

What all does the battery do?

A car battery helps supply the electricity to get your car started. It supplies power to the starter and other electrical components like coil and spark plugs and your fuel pump. With power being sent to these components your car turns on when you turn the key

What all does the alternator do?

The alternator is an important part of your car’s charging system. It generates power to power your engine while the car is running. It works by having a belt that turns the alternator pulley. This belt is driven by the engine while it is on.

In turn the alternator helps supply constant voltage to the system. It also charged your battery back up. Without this your engine would continually drain electricity from your battery until it was completely dead. The alternator is the generator of the car engine.

What are the signs of a bad battery?

A difficult time starting the car can be a sign of a bad battery. When you turn the key and you notice that the engine is struggling to start then your battery might be low. Another example would be that nothing on your dash or your interior lights turn on. This is a sign that your battery is dead.

If your battery is dead it won’t be able to supply electricity to the starter or the fuel pump. Your may hear clicks when you turn the key. Although the car won’t start completely. Another sign that you have a bad battery swelling. A battery will swell if it has gone bad. You will typically see the sides of the battery bow out. This is a sign you should get your battery tested.

If the swelling becomes too severe your may start to have a leak from the battery. This means the electrolyte solution, which consist of sulfuric acid and water, may start to drain out, Not only will you have a mess in your engine bay but the acid can burn your skin if it comes in contact. If you notice your engine is smoking you should turn off the car and check to make sure that the battery isn’t leaking.

The hydrogen gas produced by the battery is highly flammable. That being said make sure you don’t have anything that could spark a fire like a cigarette or a lighter.

What are the signs of a bad alternator?

One of the first signs of an alternator going bad is dimming lights. The lights will dim when the car is running. Don’t mistake it from dimming lights when the car is off, which could be a bad battery. When you have accessories running like your headlights or radio they draw power from the alternator.

If your alternator is going bad it will have trouble keeping the power flowing. Your alternator won’t have enough power to keep everything running so you may see lights start to dim when you turn on accessories.

Another sign of a bad alternator is the battery light. The battery light on your car’s dashboard doesn’t always mean a battery. In most instances the battery light actually refers to the charging system. And what charges the battery? Yes, you guessed it. The alternator,

If your battery light is on you’ll want to get your alternator checked. Your mechanic will make sure that the alternator is producing enough electricity and converting the electric current from AC to DC.

Other reasons why your car may not start

A car needs three things to run properly. It needs fuel, spark/electricity and compression. If any of these three are missing then you won’t be able to start your car.


If you have a fuel delivery issue your car may not start. Fuel comes from the fuel pump and flows to the fuel injectors. If any of these components fail you will have a fueling issue. In other words gas is not being supplied to your engine.

Without fuel your engine won’t start. Your mechanic can diagnose your car and find out if you have a fuel issue. You can spray starting fluid into your car’s throttle body to see if the issue is indeed fuel. Spray a little ether/starting fluid while you have someone try to turn the key.

If your car starts with the ether then you know that you have a fuel delivery issue. From there you can work out the possible causes.


If your starter is bad then your car won’t start. The starter helps spin your car’s flywheel. With the flywheel being attached to the crankshaft the turning of the starter will help turn the internal parts of the engine. If your starter is locked up then you won’t be able to start your car.

Sometimes the main assembly of the starter is bad. Other times it may just be a bad starter solenoid. You can take your starter to most auto part stores and they will test the part for free. Another trick to see if it’s your starter is to have someone try to start the car while tapping on the starter with a hammer. If your starter is stuck then the tapping may unseize the unit and it will start your car.

If your starter is bad then this can be another reason why your car won’t start up.


Gasoline engines operate by compressing air and combing that with fuel and a spark gives you combustion. This combustion or explosion creates force which pushes the pistons down. This what keeps your engine running. If your pistons have lost the ability to compress the air/fuel mixture then your car may not start.

Piston rings, otherwise known as oil rings help keep some of the air within the combustion chamber. If you have to much bleed out of the air your engine may not run. One way to test if you have the correct amount of pressure is to use a pressure tester.

Do you have to replace alternator when replacing battery?

You do not have to replace the alternator when replacing a battery. If the battery is bad then that can be the only part you replace. On the other hand you should look into why the battery went bad in the first place. Is the battery old? Batteries tend to last 3-5 years.

It’s quite common for a battery to go bad just due to it’s age and wear. You should also have your alternator tested. If your alternator hasn’t been working properly then that might’ve been why your battery went bad. By having your alternator tested you can be sure that it doesn’t need replaced.

Do you have to replace alternator belt when replacing battery?

Unless your belt is frayed or in bad shape you shouldn’t have to replace a belt during a battery change. By checking the condition of your serpentine belt you can know if it needs to be replaced. The alternator belt helps turn the alternator to produce electricity.

Do you have to replace alternator belt when replacing battery? If your alternator is working properly and producing enough electricity to charge your battery you should be ok. Again just make sure that your belt is in decent shape.

What does the battery light mean?

The battery light on a car dash signifies a charging system malfunction. While most would suspect that the battery light means the battery is bad this is not the case. In most instances, the battery light is a good sign that your alternator is going out.

Having your alternator tested is the best route to determining why your battery light is on. You may also have a grounding issue or a short that could make the battery light turn on. By taking your car to a mechanic they can diagnose the problem further.

You can also have your battery tested just as a backup. Making sure that all of the parts in the charging system will ensure that you’ll be able to start and drive your car.

How much does it cost for a battery replacement?

Having your battery replaced at an Autoparts store like Autozone is free. Auto part stores will swap out your battery and take your old one as a core exchange. If you don’t have a bad battery to exchange then you’ll probably have to pay a core charge.

Check with your local Autoparts store to see if they offer free battery replacement. Going to a mechanic shop they may charge you a fee to replace your battery. Some may charge $20 to replace a battery. On the other hand they may just charge your more for the battery to cover the se

How long does a battery replacement take?

A battery replacement can take anywhere from 10-30 minutes. Some vehicles have the battery in the back seat. In this case the battery change can take 45 minutes or more. Most batteries are in the engine compartment.

There are two terminals on the battery. The positive and the negative. These in addition with the hold-down are the pieces that have to be removed to install a new battery. As long as your terminals aren’t corroded the battery changer should be fairly quick.

Does anyone replace car batteries for free?

There are multiple auto part stores that replace batteries for free. Places like Autozone and Oreily change out your battery free of charge. Just call down to your local parts store to see if they are able to change out the battery.

In most cases the auto parts store will take the old battery as a core charge and completely change out the battery.

What is a core charge?

A core charge is basically ransom for your old car part. Things like batteries and calipers have a core charge when your purchase the. This lets the auto parts store know that they are going to get a defective part in return.

They will take the defective part and remanufacturer it so that they can make profit while not having to make a whole new part. If you don’t have a core to exchange then you will get charged a core fee.

Where can you get your battery tested for free?

Most auto part stores will check your battery for free. If you have AAA then they will test your battery. Simply drive your car to the auto parts store and request a battery check. Typically they have handheld testers to check the battery voltage and its output.

Where can you get your alternator tested for free?

You can also have your alternator tested for free at an auto parts store. Place like Autozone will come out and test your alternator to make sure that it’s working correctly. They connect to the battery while the car is running to make sure that your alternator has enough output to power your accessories and recharge the battery.

Do part stores replace alternators?

Auto part stores do not replace alternators. While they are able to sell you new parts they do not replace them at the store. For that you would have to take your car to a mechanic.

Do part stores replace batteries?

Auto part stores do replace batteries. In most cases the service is free of charge. You’ll have to purchase one of their batteries. After that they will swap out the battery and take the core as an exchange.

Do you have to replace the alternator when replacing the battery?

You do not have to replace the alternator the same time you replace the battery, In most cases one or the other will be bad. If your alternator isn’t working then your car may have been draining your battery. In that case you battery may need charged.

Although in some occurences the battery may not be able to hold a charge anymore. That means that even though your alternator was the main culprit it decided to take the battery along with it. This is the time where you would need to replace both the alternator and the battery.

With regular maintenance and checks you can be sure that your car is in the ideal shape. If you catch something early on they you can prevent yourself from having to replace multiple parts going bad.

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