A guide to car batteries

How does a car battery work? And how long will it last? Here’s our guide to the ins and outs of car batteries, and what to do if yours dies. 

How does a car battery work? And how long will it last? Here’s our guide to the ins and outs of car batteries, and what to do if yours dies. 

Daniel Hutson
From the Motor team
minute read
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Posted 14 JANUARY 2020

What does a car battery do?

A car battery supplies electricity to your car’s starter motor, which is what gets the engine going. The battery also powers up the radio, lights and on-board computer.

How much does a car battery cost?

That depends on the type of battery you need, and where you buy it from. Car batteries range between £53 and £260. But you’ll also need to factor in the cost of fitting it.  

Can I change a car battery myself? 

It’s not a good idea. Knowing which type of car battery to fit takes expertise. And if you make a mistake it could be dangerous, as well as expensive to put right. Only a trained mechanic will be able to tell if the fault is with the battery or the car itself. 

How long do car batteries last? 

A car battery should last around five years. But it could wear down quicker if you make lots of small journeys. Other factors affecting your battery’s lifespan include the temperature and how you treat the car. 

How do I know if I need to replace my car battery?

Here are a few telltale signs that your car battery needs replacing:

  • the car is slow to start
  • the electrics don’t work
  • the dashboard warning symbol is illuminated.

How do I avoid running down my car battery? 

There are a few ways that could prolong the life of your car battery:

  • don’t use the radio or other electronics when the car’s engine is off
  • take a look at the battery. Is there gunk on the cables? If so, there are products you can buy to remove it 
  • avoid making lots of short journeys
  • when you leave the car, make sure all internal lights and the headlights are turned off.

What do I do if my car battery dies? 

Firstly, remember you’re not alone. Around two-thirds of UK breakdown callouts are the result of dead car batteries. This happens most often when people leave the lights on while the engine’s not running. Easy to forget, especially if you’re a new driver.

But you may be able to fix the problem yourself by jump-starting the car. For that, you’ll need some jump leads and a driver who’s willing to attach them to their own car. After you’ve started the engine, keep driving for at least half an hour until your own battery has charged. 

It might be worth keeping a battery charger in your boot at all times, in case your battery dies and there isn’t another driver around to help you. 

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