How to Change a Car Battery and How to Test It

14th Jul 2023

By Veronica Chiarelli

A guide to changing your car’s battery

Changing a car battery is a problem many of us will face at some point. Leaving your cars lights on overnight or the car's age could also speed up wear on your battery. This guide will walk you through the process of removing the old battery and replacing it with a brand new one.


What is a car battery and how long does it last?

Car Battery Under Bonnet

A car battery is a rechargeable source of electricity used to store and power the electric components of a vehicle. It’s usually located under the bonnet in the engine compartment. The battery is used to start the motor and to power the vehicle’s electrical systems.

The life spam of a brand new battery is three to four years on average, but what’s going to determine how long the battery is going to last is your usage.

What are the signs of a bad battery?

Mechanic Looking Under Bonnet In Car

If you’re having problems with your car, you could be running low or have drained out the battery. Here are the signs you’re battery has gone bad:

No response when turning the key

If it takes multiple attempts to start the car, there are no lights on the dashboard or you can’t even start the car at all your vehicle could have ran of out battery. It’s important to pay attention to the signs your car gives you. If you notice that your vehicle is starting slowly at some point this could be a sign that the battery is weakening and you need to change it.

Dim lights

A weak battery could be the cause of dim headlights, internal lights and other electric components in your car. It’s definitely worth checking the battery if you’re facing these problems when starting your vehicle.

Damaged battery

If you notice that your battery is leaking, has cracks, the battery case is bloated or is damaged in any other way, it’s crucial to change it immediately.


It’s important to check the battery’s age even before it presents signs of weakness. As mentioned, a brand new battery life spam is about four years and as it gets older it loses the ability to hold charge causing lower performance.

How to remove old battery

Removing Battery From Car

The first thing you need to check is where your battery is located. Usually, the battery is located under the bonnet but if this isn’t the case you can check your car’s owner’s manual. Once you’ve found it put on gloves and goggles. Sometimes old or damaged batteries can leak an acid liquid or give out electric shocks so you want to be protected to avoid accidents.

The second step is to find out which terminal is which. It’s important to disconnect the negative (-)terminal first and then disconnect the positive (+). If you disconnect the other way around you could cause sparks and electric shocks.

Now this is the time to remove the battery. Make sure the connectors are away from each other, remove any covers and unscrew the restraining bolts.

Battery connectors corrode over time so you should give the battery tray a good clean before fitting the new one in. You can use battery cleaner and a wire brush for this.

How to change a car’s battery

Checking Battery In Car

Here’s the step by step on how you can change your car’s battery:


Even though this is a step a lot of people skip, it’s important to take precautions to make sure you’ll be safe while changing your car’s battery. It’s not uncommon for batteries to leak an acid liquid that can injury hands and eyes if you’re not wearing the necessary protection googles and gloves.

You also have to take into consideration that a car battery, like any other electric source, could shock you. Don’t touch anything without the protective gloves to avoid getting electrocuted.

Install and secure new battery

Place the new battery on the battery tray making sure it matches the correct connectors (positive and negative). Connect the positive (+) connector first and then connect the negative (-). Screw the restraining bolt back and give it a gentle shake to make sure it’s secure.

Test the connection

Now test the connection by starting the car. Try to turn on the headlights, radio, infotainment system and everything powered by electricity to make sure everything is working properly.

Get your battery change with Evans Halshaw vehicle servicing and repairs

Changing your car’s battery is a relatively easy job that can be completed in less than an hour. The most important thing is to wear goggles and gloves to avoid accidents and make sure you’re unplugging the connectors in the correct order.

If you’re still unsure on how to change your car’s battery and would like assistance, Evans Halshaw offer vehicle servicing and repairs.