What to do if you have a flat battery

What to do if you have a flat battery
Even the most prepared drivers can take their cars for granted and end up with a flat battery.

With a lot of us still at home for all but essential journeys, we might not even realise our battery is going flat until it's too late.

Here's how to diagnose and fix a drained battery, and learn how to prevent your car from losing charge.

What to do if you have a flat battery

  1. Check that the battery is definitely the cause of a non-start using our tips
  2. Jump start the car yourself, or
  3. Call RAC Breakdown on 0330 159 1111, we’ll be happy to help even if you’re not a member

How to tell if you have a flat battery

Your car’s engine might not start for a number of reasons. To make sure the problem is definitely your battery, try checking the following:

  • Are the dashboard warning lights turning on?
  • Are interior lights and electric windows working?
  • Are there problems with central locking?

If you answered no to any of the above, your battery might be flat. However, there are a few things to remember:

  • Your battery might hold enough charge to turn on warning lights but struggle to turn on the engine. Dimly-lit icons are usually a big giveaway.
  • If your central locking is playing up, your key fob might be the problem. Try a spare set to help pinpoint the fault.
  • If you can’t turn the ignition key, your front tyre might be jammed against the kerb. Try turning your steering wheel away from the kerb, or rock the steering wheel from side to side as you turn the key.

Jump starting a car yourself 

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If you want to jump start the car yourself you’ll need:

  • jump leads
  • a second vehicle with a well-charged battery
  • the confidence to take on the job

Our video guide on how to jump start a car explains everything you need to do in 10 simple steps.

What to do when calling the RAC

After you’ve given us a call on 0330 159 1111, there are a couple of important things you can do while you wait for us to arrive.

First, don’t attempt to start the engine or jump start your car yourself. You should also switch off any electrics in the car – such as radios, dash cams, chargers etc.

This will let our patrols test your battery correctly and help get your car up and running quickly.

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How RAC patrols will help

Our technicians will test your battery to see if it’s faulty and if it needs to be replaced. They’ll only recommend a new battery if it’s absolutely necessary.

We’ll fit a high-quality battery with up to 5 years warranty, and under our price match guarantee. 

If your existing battery is in good shape, we’ll jump start your car and have you back on the road in no time. 

How we test your battery

flat-battery-what-to-do-tester

Our patrols use advanced battery testers to check if: 

  • the condition of your battery is deteriorating and will need to be replaced soon
  • your battery has a fault and needs to be replaced straight away
  • your battery has run flat and needs a simple recharge

We can also see if there’s a problem with your car’s charging and starter system. Our state of the art battery tester can even highlight if a specific device in your car is draining the battery.

Technicians will talk you through the test results which can be printed on the roadside, whilst we're attending your breakdown at home, or sent to you by email.

When to replace a car battery

Batteries typically last for five years. However, this can vary depending on the quality of the battery and how your vehicle is used and maintained.

Frequent, short journeys prevent your battery from fully charging, eventually reducing charge capacity over time. Infrequent use of your car could also mean that your battery deteriorates faster.

If you can park your car in a garage, you’ll also protect your battery from the elements. Cold, flat batteries are one of the main reasons our patrols are called out during winter months.

Common reasons that batteries go flat

We’ve already learned that batteries can go flat because of repeated short journeys, infrequent use and cold conditions – but there are plenty of other reasons why your battery might lose charge. 

Some common causes include:

  • leaving your lights on unnecessarily or mistakenly when parked
  • leaving dashcams and other devices plugged in
  • faults in batteries
  • faults in the charging system

If healthy batteries go repeatedly flat this can affect their ability to hold charge in the long term.

For advice on how to keep your battery healthy from home, see our How to look after your car during lockdown page.

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