If your car won't start, there's a good chance the battery's gone flat. A flat battery is one of the top 10 breakdown causes. Here's what to do:
1. Double check that it's a flat battery
- Make sure there's fuel in the tank.
- If the central locking isn't working, your key fob might have died so try a spare key.
- If you can't turn the ignition, check the wheels aren't jammed against the kerb.
2. If you think it's likely a flat battery, try jump-starting your car.
3. If you can't jump start your car, get in touch so we can charge or replace your car battery.
We provide 24/7 roadside assistance.
What we'll do to help
If you've got a flat battery, we won’t just jump-start you and send you on your way. As well as charging or replacing your battery, we'll try to find out why it went flat in the first place.
If we can't see why the battery died or we think it's faulty, we'll carry out a battery test. Our test is very thorough and we'll only ever recommend a new car battery if you really need one.
Once we reach you, we'll:
- Test your car battery
- Look at your car's charging system
- Check for a fault that could've drained your battery
- Partially charge your battery or replace it, if required, so you can continue your journey.
Find out more about our specialist battery testers here.
Testing your car battery’s health
We get an immediate printout of your battery readings so we can check the condition of the battery.
The different readings can be:
1. Good battery:
- The fault's not with the battery.
- We’ll check your car’s charging system and find out why it broke down.
2. A bad cell:
- Car batteries contain several 2-volt batteries known as cells.
- If one's not working, the battery will need to be replaced.
3. Replace battery:
- This reading is clear - the battery’s just not up to it anymore.
4. Needs charging:
- This means that your battery's working, but it needs a full recharge.
- We’ll check your charging system to find out of what drained it.
- Next, we'll give you a jump start to get the engine going.
- Before you go, we'll advise how to fully recharge the battery.
5. Consider replacement:
- Your car battery passed the test - but only just.
- This means the battery's coming to the end of its life.
- We'll advise how soon you should change the battery based on how you use your vehicle.
When to replace a car battery
There's no hard rule about how long car batteries should last or when they should be replaced.
Most batteries will last somewhere between 5 and 7 years. However, our mechanics see cases where the battery has failed after only 2 or 3 years because of how the car was driven.
As a rough rule of thumb:
If the engine struggles to start before the battery is 5 years old, it probably means:
- The battery isn't getting enough charge.
- The car's doing too many short journeys, or
- There's a vehicle fault draining the battery or affecting charging.
Starting problems after 5 years are more likely to mean:
- The battery's getting tired and may need replacing.
Find out how breakdown cover can help you if you have car trouble:
Dead battery? We'll replace it the same day with Battery Assist.
Why do car batteries go flat?
Most car batteries fail because they don’t get the chance to recharge properly.
You can halve the battery's lifetime by not fully charging it regularly. This costs you money and risks your car having a breakdown.
There are all sorts of reasons for a dead battery, but the most common are:
- The car hasn't been used for a while
- The car's only used for short or stop-start journeys
- The lights were left on
- There's a faulty component
- There's a problem with the car’s charging system
- You've got a fault with the battery itself
Batteries can fail for other reasons, like too much vibration from the engine, over-charging, corrosion and extreme temperatures. Flat batteries are the most common reason why cars won't start in winter.
Plus, modern cars have lots more power-hungry electronics than older cars used to. Think of built-in sat navs, infotainment systems, seat heaters and USB plugs. All of them put strain on the battery.
Broken down in the UK? We’ll rescue you, even if you’re not a Member.
How to keep your car battery healthy
There are a few ways you can avoid getting a flat battery and help your car's battery last longer:
1. Go for regular drives
- 30 minutes or more will help the battery recharge.
2. Invest in an intelligent charger
- If you don't use the car much, you can leave these connected for long periods without damaging the battery.
3. Try a solar charger
- It won't charge a flat battery, but it'll help to keep the battery charged on a vehicle you don't use much.
4. Switch all electrics off
- Make sure all electricals like heaters, windscreen wipers and stereo are off when you park or start the car.
5. Dip the clutch
- Dip the clutch when you start the car to take some load off the starter motor and the battery.
Flat battery help with Battery Assist
In 2018, a flat battery was the second-biggest reason why our Members broke down, and we were called out to more than 300,000 of them.*
Our Battery Assist service will help you whether you're a Member or not. And you can also call us out even if it's not an emergency breakdown.
If your battery goes flat, we'll charge it or replace it so you can carry on your journey.
*Source: 313,162 AA Attended Breakdowns for batteries, January 2018 – December 2018
Published: 7 April 2016 | Updated: 11 December 2019 | Author: The AA