How to change a car battery We've all been there. It’s a cold winter morning, you’re in a rush and need to get to work but the car just will not start. The first port of call is usually the battery - it’s not always the case, but it’s a good place to start.
Before doing anything it’s worth checking if the battery needs changing at all - you may just need to give it a good charge, in which case head over to our guide on how to charge a car battery and we’ll talk you through it. At this point it’s also worth checking that the battery terminals are clean and getting a good, solid connection. If you’re ever unsure, then the best advice we can provide is to have your battery fitted by a professional, however even to the uninitiated it is not as hard as you may think and can save you time and money. Ok - let’s get that battery changed!
First things first, we need to make sure we have the right tools for the job, you’ll need:
- A socket set (typically a 10mm or 13mm socket)
- An adjustable spanner
- Safety goggles
- Rubber gloves
- Any radio and data codes your vehicle may require.
Before locating your battery ensure that your vehicle ignition is turned off and the keys have been removed. This step should ensure that the battery is providing no power at all to the vehicle and will reduce the chance of any sparks or shocks. If you do experience any sparks after doing this it would be worth having the problem investigated further by a professional.
Clean the battery terminals. You may notice a white powder, rust or paste covering your terminals or leads, we’re looking to remove this entirely so we can ensure a good connection on the new battery and make it easier to disconnect the terminals. The best way to clean the battery terminals would be to apply some WD40 to them directly and then brush with a stiff hand brush.
Next we need to check the old battery for any damage or cracks which may produce acid leakage. The acid contained inside car batteries is extremely corrosive so you need to handle this step with care. If there is any damage remember where so you can prevent any spillage or injury risk whilst removing the battery.
Tools at the ready it is now time to get that old car battery out, before starting make sure that all of your tools are away from the battery. This stage requires caution so please read carefully. Start with the negative terminal and in an anticlockwise motion unscrew the nut slowly. Then slowly lift the clamp up and it should slide off. If the clamp will not lift off try applying some more WD40 and prise the clamp off carefully. Repeat the process on the positive clamp. Most battery clamps require either a 10mm or 13mm socket.
Remove the battery securing plate or bar. These plates either clamp the battery to the tray at the bottom or sometimes over the top. Again these normally require a 10mm or 13mm socket. If the nut is rusty then apply some WD40 to help remove the nut.
Proceed to lift the battery out of the vehicle. Remember they can be heavy so ensure you are braced to lift a potentially heavy item. Don’t forget about any sections of leakage or damage you may have noted earlier!
With the old battery out of the vehicle check again the battery leads and clamps to ensure they are clean and ready to go on the new battery.
You are now ready to install your new battery. If your new battery has plastic caps protecting the posts then keep them on at this stage as they will help you to identify the positive and negative posts - red and black. Carefully place your new battery in the battery tray.
Now we need to reverse the process in removing the old battery. So, start by removing the plastic terminal cover off the new battery and secure the correct positive clamp to the battery. Repeat this process with the negative terminal. It may be worthwhile adding some fresh grease to the terminals to ensure a good connection.
Reattach the clamp or bar that fastens the battery into the battery tray. Don’t forget this step as you don't want your new battery jumping out of that tray!
Now start your ignition - all being well your car should start up without any delay. Please remember that you may have lost some data or radio codes during the process as you have disconnected the battery, so enter those now. This is perfectly normal and varies from car to car, but always check your owners manual if you are unsure.
By this stage you should have successfully replaced your battery. The last point is a reminder to dispose of your old battery correctly, at a local recycling point, scrap yard or garage. Please don’t skip this step - the chemicals contained in car batteries are very dangerous and need disposing of correctly.