Ellie Dyer-Brown
Thursday January 18 2024
5 min read
Changing a car battery is a job you can do at home with the right tools and knowledge. This guide explains the process in seven easy-to-follow steps.
Before starting, take a moment to ask yourself whether you feel confident. If the answer is no or you have any doubts, don't risk your safety - contact a mechanic instead.
How to tell if your car battery needs replacing
Just as cars display various symptoms when something is wrong, batteries do the same. Nobody wants to miss an appointment due to their car not starting; by familiarising yourself with the early signs of battery failure, you can avoid that situation.
Your battery might need replacing if:
There is a build-up of green, powdery residue on the terminals.
You can see a battery warning light on your dashboard.
The engine takes longer to start and feels like it's struggling.
Your car is experiencing electrical issues.
How to find out what battery your car needs
It's important to ensure you use the correct battery for your car. For instance, vehicles that use stop-start technology require a different type of battery, capable of withstanding additional stress.
You should be able to find this information in your vehicle handbook. Alternatively, use this handy battery look up tool from Varta.
How to change a car battery
There are a couple of things to do before you get started. You may need to reset your car’s electrical systems (sat nav, radio etc) after changing the battery, so make sure you have the pin codes and other information needed.
For extra safety, you could pop on some gloves - battery acid is highly corrosive and can cause nasty burns if it leaks.
Step One - Prepare your car
Make sure you are safely parked on a flat surface with the engine switched off.
Double check the handbrake is engaged, and keep your keys with you in case your car’s central locking system activates when the old battery is moved.
Step Two - Disconnect the negative terminal
After locating the battery (your vehicle handbook should explain where it is), start by disconnecting the negative terminal, which should be marked with a '-' symbol or 'Neg'.
Use a spanner or pliers to loosen the bolt or nut that secures the cable to the terminal.
When it is loose, twist and pull the cable away from the terminal in a gentle motion.
Avoid touching any metal components with the cable.
Step Three - Disconnect the positive terminal
The positive terminal should be marked with a '+' or 'Pos'.
Repeat the same process discussed in step two.
Step Four - Remove the hold-down bracket
The battery in some cars is secured by a hold-down bracket, which you need to remove.
Step Five - Lift the battery
Gently remove the battery from the tray, taking care not to spill any acid.
Before putting your new battery in, you could give the tray a quick clean.
Step Six - Put your new battery in
Follow the same steps as above in reverse.
Start by connecting the positive terminal, followed by the negative terminal.
Once finished, double check the connections.
Step Seven - Switch the engine on
Once you’ve disposed of your old battery and connected the new one, take your key and stick it in the ignition. You're ready to drive away!
With the right tools and guidance, changing a car battery yourself is a relatively simple task that could save you some money.
Want to try charging your battery instead? Read this guide.
How to make your car battery last longer
Car batteries are good at looking after themselves - they require minimum fuss and little maintenance. However, forgetting to switch the lights off and keeping the air-conditioning and stereo on whilst the engine is off will eventually drain the battery.
It's also important to remember that starting your car is the most demanding thing a battery has to do. Short stop-start journeys mean that the battery does not get the chance to be fully recharged by the alternator, giving it a shorter life span.
Check out this guide for more tips to extend the life of your battery.
Things you should know about car batteries
A car battery is a significant component for starting a car. It is also a crucial part of the electrical system, running everything from the stereo to the lights, electric windows, heater and much more. The alternator charges it while the vehicle is moving.
Most combustion engine vehicles use lead-acid batteries, consisting of a plastic case filled with a sulphuric acid electrolyte solution and lead plates.
As with most new things, newer batteries are often of better quality - in theory, they should last longer than a car battery purchased ten years ago, but they're also more expensive. Find out why your new car's battery will cost more to replace in this guide.
If you need a new battery for your car and don't fancy fitting it yourself, FixMyCar is here to help, providing a nationwide network of expert mechanics right at your fingertips.
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Ellie is FixMyCar's Content Manager. She has over three years of experience writing about cars and regularly collaborates with automotive experts to provide trustworthy advice for drivers that is easy understand. Her work has been featured in Yahoo! Finance, iNews, The Daily Express and The Sun. She has a BA in English literature and an MA in creative writing from Durham University. Outside of work, Ellie follows F1 and eagerly awaits Ferrari's next era of dominance in the sport. She drives a Suzuki Swift.