How to change a car battery

A battery is an essential component in a car. Here's our guide on how to change a car battery when the time comes for a new one

By Trinity Francis November 16, 2022

There’s no exact science when it comes to car electrics. Some vehicles seemingly have a ghost in the machine but if there are any unusual changes to the vehicle's electrics, it’s a good idea to get the battery looked over.

Even if the electrics seem to be in good working order, a new battery is advised approximately every five years. A car might need a new battery if it is struggling to start even on mild or warm days. When it’s cold it takes more energy to start an engine so if the car will not start on warm days this could mean the battery is getting old and needs replacing.

On modern cars, a warning light may come on if the system detects the current battery is not efficient enough anymore. If the battery is charged and then loses its charge within a couple of days then this is also a good indicator that a replacement is required.

Although these are generally signs of an old battery, these issues can stem from a faulty alternator so before getting a new battery, ask a garage to check the battery function to determine that is the root cause.

If the vehicle regularly travels only short distances this can impact battery health. Short trips mean the battery does not have a lot of time to recharge, it’s a good idea to include some longer journeys to keep the battery in good working order.

What to do if your battery needs to be replaced

If your battery needs replacing or you suspect it’s time to get a new one the best option is to take the vehicle to a garage. A mechanic will be able to determine which battery will best suit the vehicle. Retail services like Halfords also sell and install batteries.

Often, batteries come with a warranty (generally up to five years), so if there are any manufacturer faults in that time the battery can be replaced. Whilst the installation process can be relatively straightforward for some vehicles, it’s always best to get a professional to fit a new battery to ensure the warranty is valid.

Incorrect installation can damage a battery and other components in the vehicle so a trained technician will be able to fit it safely. Batteries are also potential fire hazards, a professional service will be able to correctly dispose of the old battery.

Before the battery is changed, ensure the existing battery is tested to make sure that is the cause of any electrical issues. When the battery change is complete, make sure the battery cover is placed back on securely.

What car battery do I need?

At a garage, the technician will be able to advise the best type of battery for the vehicle. Where possible, opt for a like-for-like replacement. There are several types of batteries on the market, these are three main types.

Lead-acid batteries are the most common type of battery, these are estimated to last for at least 20,000 starts and are generally the cheapest option.

Calcium batteries are more powerful than lead-acid batteries and offer approximately 30,000 starts.

AGM or EFB batteries are used in vehicles with start/stop technology as they are better suited to an increased number of starts and rated for up to 360,000 starts. These are the most expensive type of battery and the installation process is more complex than lead-acid and calcium batteries.

How much will a battery cost

For a Ford Fiesta, if the vehicle has a start/stop button an EFB battery can range from £150 to £200 including installation. Without a start/stop function, lead-acid, or calcium batteries are cheaper, at around £100 to £150.

A Mercedes A-Class requires a more powerful battery as it has a start/stop function and a range of diesel engines that need more energy to start. An AGM battery starts at £200 including installation and can cost up to £250.

Towards the top end, a BMW X5 needs an AGM battery that can cost anywhere between £250 and £350 including installation.

How to keep a battery in good condition

To keep a battery in the best condition it’s a good idea to avoid using electrical components like the radio or lights for a long time when the engine is not on. This can drain the battery and without the engine on the battery will not recharge.

Taking care of the battery is another maintenance requirement to add to the list. It’s advised that every two to four years the battery is checked to ensure it’s in good condition. If a battery check does indicate the battery is getting old, try to replace the battery with something closely comparable.

If a vehicle is likely to be undriven for a while the battery can lose charge over time. To prevent the battery from being drained it can be hooked up to a trickle charge lead which maintains the charge over an extended period. In a similar way, lots of short journeys can deplete the battery, longer trips will give the battery a chance to fully charge.