08 January 2025
How to change a car battery: Your step-by-step guide
5 minutes
If you’ve ever accidentally left your headlights on overnight, you might be greeted with the sound of silence when you try to start your car the next morning.
A flat or dead battery can stop you in your tracks. If you’ve tried charging the battery and gotten nowhere, you might need a new one.
The good news is that replacing a battery is a pretty straightforward job.
Here, we explore the importance of maintaining a car battery, including how to know when to replace it and how to change a car battery step by step.
Can I replace a car battery by myself?
First, is replacing a car battery something you can do even without experience? Or is it better left to the professionals?
Like most car maintenance, it ultimately depends on your confidence when you pop open your car’s bonnet. Switching out an old battery for a new one is a relatively simple job, but if you find the sight of the engine a little overwhelming, you can always ask for help.
If you have breakdown cover, you can call for assistance, whether your car is at home or by the roadside.
How do I know when I need to replace my car battery?
There are a few telltale signs that it’s time to change your car battery, including:
- The age of the battery: If it hasn’t been changed in 5+ years, it might be time for a new one.
- Dim or flickering headlights: This could indicate a problem with the vehicle’s electrical power.
- A clicking sound: When you turn the key or press the start button, you may hear an unusual clicking noise.
- Dashboard warning light: Your car may have a battery indicator light that comes on when the battery isn’t charging properly.
- Frequent jump starts: If you need to keep jump-starting your car, your battery might be coming to the end of its lifespan.
- Swollen battery casing: The case that houses the battery could start swelling up, suggesting the cells inside are about to rupture.
- An unpleasant smell: Leaking battery acid can sometimes smell like rotten eggs.
How to replace your car battery at home: Step-by-step
Your car’s battery is the rechargeable electrical source used to store and power the electric components of your vehicle. A brand-new battery can last between 3 and 5 years, but if you drive more than the average motorist, you could need to replace it sooner rather than later.
Changing a car battery: Before you start
To replace your car’s battery, you’ll need to prepare the following:
- New battery (make sure it’s the correct size and voltage for your vehicle — check the owner’s manual or with the manufacturer if you’re unsure)
- Wrench or spanner (typically 10mm or 13mm, depending on your car)
- Battery terminal cleaner and a wire brush
- Protective gloves and safety glasses
- Remove metal jewellery
- Wear old clothes that you don’t mind getting dirty
- Car manual (helpful for battery location and size)
Step One: Set up a safe workspace
Safety is paramount when switching out an old battery for a new one. Follow these tips to change your battery without incident:
- If you can, park your car on a level surface away from any other traffic or hazards and leave yourself plenty of room to work. If you’re working in your garage, make sure it’s well-ventilated (keep the door open).
- Next, turn off the ignition and remove the keys (if necessary) to ensure no power flows to the battery. If you've been driving a lot beforehand, you may also want to wait 10-15 minutes to let the engine cool down first.
- Finally, put on your protective gloves and safety glasses or goggles. Car batteries can leak acid, and sparks can fly. Keep your hands, arms, and eyes covered throughout.
Step Two: Remove the old battery
Start by locating your battery. It’s usually under the bonnet, but some cars keep it in the boot or under the back seats. If you're unsure, check your car’s owner’s manual.
Next, identify which terminal is which:
- The negative terminal usually has a black cover and/or is marked with a “-” symbol.
- The positive terminal is typically red with a “+” sign.
Next, remove any straps or bolts holding the battery in place. Some car batteries are secured by a clamp or bracket that must first be undone.
Carefully lift the old battery out of the tray. A car battery can be heavy (sometimes up to 20kg), so use both hands and make sure you have a good grip to avoid dropping it.
Finally, safely set the old battery aside, ready to be disposed of later (more on that below).
Step Three: Clean the tray
The battery terminals can corrode over time. If you notice a white, powdery substance, it’s corrosion, which can interfere with the connection. Use your wire brush and battery terminal cleaner to scrub it off.
At the same time, clean the tray where the battery sits. This will help prevent dirt and corrosion from affecting the new battery.
Step Four: Install the new battery
You’re ready to place the new battery on the tray, ensuring it fits securely and matches the correct (positive and negative) connections.
- Connect the positive (+) connector first: Slide the cable over the terminal and tighten the nut with your spanner. Make sure it’s secure, but don’t overtighten. Then, gently shake it to check if it’s attached properly.
- Connect the negative (-) terminal next, following the same process.
If you have anti-corrosion grease or petroleum jelly (Vaseline), you can apply a small amount to both terminals to help prevent rust.
Step Five: Final checks and testing
Finally, the moment of truth: Test the connection by starting the car and then turning on the headlights, radio, and anything else powered by electricity to ensure everything works correctly.
The dashboard should show no warning lights. You may need to reset your alarm, clock, radio, and navigation system.
How to change a car battery without losing settings in the UK?
If you want to replace a battery in a car without losing your settings, you’ll need a car memory saver device. This gives your vehicle power while you swap over batteries, keeping your settings (such as radio station presets and navigation info) intact.
How much does a new car battery cost?
The average price for a new car battery is around £200. However, car batteries can vary in size, quality, and cost, and the make and model of your car can limit your choices. For example, luxury or modern vehicles may require a more expensive battery.
Where should you take an old car battery to be recycled?
Car batteries must undergo a long clean-up process before being recycled, so it’s vital that you dispose of your used battery correctly and responsibly. Check to see if the following accept old car batteries:
- Local recycling centres
- Scrap metal facilities
- Local garages
- Your vehicle’s manufacturer
In summary: How to change a car battery in the UK
To recap, changing a car battery is a pretty simple job — so long as you follow the steps outlined above.
Remember to take your time and prioritise your safety. Wear safety gloves and glasses throughout to protect your hands and eyes from sparks or leaks.
However, if you’re unsure or feel uncomfortable, it’s always safer to seek help from a professional mechanic.
Are you looking for car insurance cover? Get in touch with us! A member of the Howden team would love to help you find the perfect policy!