How To Change A Car Battery

If you’re faced with a car that’s refusing to start and a battery that won’t hold any charge, it could be time to change your car battery.

Changing a car battery is one of the more straightforward tasks you can tackle yourself. Whether you’re a beginner or just need a refresher, our expert team at Euro Car Parts have put together a step-by-step guide to help you change your car battery correctly and safely.

We’ll cover the tools you need and clear instructions for every stage of the process to get you back on the road in no time. If you’re still searching for the right replacement battery, look no further than our wide range of car batteries from trusted brands like Bosch and Lion to help get you started.

What’s Included In This Article?

• Tools you’ll need

• How often do you need to change your car battery?

• Warning signs your car battery is faulty

• Step-by-step guide to changing a car battery

• FAQs

Tools You’ll Need

Before you tackle your replacement, you’ll need to make sure you’ve got all the right tools to hand. We’d recommend the following:

• A new battery that’s the correct specifications for your vehicle

• Diagnostic tool (if the battery is stop-start)

• Adjustable pliers

• Socket wrench or socket wrench set (you’ll usually need 10mm or 13mm sizes)

• Insulated, sturdy gloves

• Safety glasses

• A torch for better visibility in the hard-to-reach areas

• Wire brush and a bicarbonate of soda and water solution

How Often Do You Need To Change Your Car Battery?

Most car batteries last between 3 to 5 years, but this can vary depending on your driving habits, climate, and how well you maintain your vehicle. We recommend checking your battery at least twice yearly to identify any issues before you’re left stranded.

Warning Signs Your Car Battery Is Faulty

If you spot any of these warning signs, it's possible that your battery is past saving and will need to be replaced rather than charged;

• Your battery is more than 5 years old

• Your car struggles to start

• Your start-stop function stops working

• Your electrical systems aren’t working properly

• Jump starts and charging aren’t reviving your battery

• You notice swelling or damage to the battery’s casing

Think your battery might just be flat, rather than dead? Read our guide on how to jump start a car to rule out any charging problems.

Step-By-Step Guide To Changing A Car Battery

Step 1. Park with the engine off

Make sure you’re parked on a flat surface with the engine turned off, keys removed and handbrake engaged.

Step 2. Locate the battery

Most batteries are housed in the engine bay under the bonnet, but some can be in the boot or floor. If it is in the engine bay, prop the bonnet open with your car’s support arm and locate your battery. It will be the rectangular box near your engine with two cables attached to it.

Look for the two terminals on the top. The positive terminal will be marked with a plus sign and will usually have a red cover or cable. The negative terminal will have a minus sign and a black cover or cable. It’s important for your safety that you’ve identified which is which before starting.

Step 3. Disconnect the negative terminal first

Using your wrench, loosen the nut on the negative terminal and carefully lift the cable away from the terminal so it can’t accidentally touch it again.

Step 4. Disconnect the positive terminal

Now repeat this process for the positive terminal, unscrewing the nut and removing the cable. Make sure both cables are separate and kept away from any metal parts.

Step 5. Remove the battery hold-down clamp or bracket

Most batteries are also secured with a clamp or bracket. Remove the fastenings or bolts and keep them safely to the side for your new battery.

Step 6. Lift out the old battery

Car batteries are surprisingly heavy, so lift your old battery out carefully using the built-in handles to help you. Make sure to keep it level as you lift, without spilling any acid.

Step 7. Clean the battery tray and cables

Before installing the new battery, clean the battery tray and remove any white or blue-green corrosion on your cable ends with the wire brush and solution. This will help a better connection with your new battery.

Step 8. Install the new battery

Carefully lower the new battery into the tray, making sure it’s correctly aligned with the positive and negative terminals in the same positions as before. Reattach the hold-down clamp or bracket and securely tighten it.

Note: if you have a stop-start battery, it’ll need to be coded into your car’s BMS (Battery Management System) in order to keep your systems running. If your battery isn’t linked into your electrical system, it won’t work to its full potential and is likely to degrade more quickly – so it's important to reprogram it correctly. Because of this, it’s best to leave a stop-start battery replacement to an expert.

Step 9. Reconnect the terminals

To reconnect, you’ll need to reverse the process, connecting the positive terminal first and tightening the nut. Then connect the negative terminal in the same way, making sure they’re secure but not overly tight.

Step 10. Start the car to test the battery

Once your new battery is stable and connected, start your engine to test everything is working properly.

Step 11. Properly dispose of your old car battery

Since it contains hazardous materials, your old car battery will need to be taken to a recycling centre to be properly taken care of. You can also bring your dead battery to your local Euro Car Parts store, and we can handle the recycling for you.

Job done! With this step-by-step guide and your new battery, your car should be running smoothly. For more in-depth information to keep you powered up, our experts have covered everything from finding which battery you need to the ultimate car battery guide.

FAQs

Can I change my car battery myself?

Most people can change their own car battery, so if you’re comfortable doing more basic car maintenance jobs and have the right tools, you can save money by doing it yourself. If you’re not as confident, if your car has more complex electronics or is in a hard-to-reach location, we recommend getting your car battery fitted professionally to ensure your safety and peace of mind.

Do I need to drive my car after changing the battery?

You don’t need to drive immediately after fitting a new battery, but it’s worth taking your car for a short drive soon after to help top up your new battery’s charge.

What problems are possible after disconnecting a car battery?

When you disconnect your battery, your electronic systems will lose power and reset. Your battery also helps protect your electronics from any power surges, so always make sure to turn off your car before disconnecting your battery.

After reconnecting a new battery, you may need to recalibrate some electronic settings and you may notice a difference in gear shifting and idling, but these will resolve themselves quickly.

Do I need to reset my car computer after replacing the battery?

This will depend on your car’s age and model. Most modern cars with stop-start functions have a BMS (Battery Management System), so you’ll need to reconfigure your new battery to your car’s computer to make sure you’re maintaining your battery health. In older cars, you won’t need to reset the computer as it will quickly relearn your battery settings once driving.