What to do when your car battery is dead

Ellie Dyer-Brown, 2 years ago

5 min read

  • Advice
  • what
  • when
Looking under car hood image

If your car battery has died, then jump starting a battery is always the fastest option for getting your car running again. However, you’ll need another car and person to help as the job requires linking two cars with jump leads.

If you have a friend or family member you can call to help, give that a try if you know what you are doing. If no one is available to help, you can use WhoCanFixMyCar to find quotes from mechanics in your area to fit a new battery for you.

Guide Contents:

How to tell if your battery is dead

What are the symptoms of a dead battery

What to do if your car battery is drained

How to jump start a car with a dead battery

Warning: Be careful around your battery

What causes a car battery to die?

How much does a new battery cost?

 Find a mechanic to diagnose or fit your battery

How to tell if your car battery is dead

If your car won’t start, it could be that the battery has died.

Most batteries need to be replaced every 3 to 5 years, and you may notice if you have an older battery that it doesn’t hold charge as well as it once did. For example, in very cold or very hot weather your engine will struggle to start. In this case, the best course of action is to replace the battery before it goes for good, which will typically happen when you need your car the most!

However, if your battery goes flat unexpectedly, have a look around to see if you’ve left an interior light or your headlights on. This is the most common cause of a flat battery apart from old age. 

Worried it might not be a problem with your battery? Here are eight possible reasons your car won't start.

What are the symptoms of a dead car battery?

There are three important signs to look out for. 

The first is trouble starting your car. You might notice that the engine cranks more slowly than usual and seems to take a long time to get going. 

Secondly, you might lose electrical power within your car. The battery doesn’t just power the engine - it powers things like your radio, electric windows and heaters as well. If these things stop functioning, or don’t function as well as they used to, it’s a sign that your battery is on its way out.

The final and most obvious sign is a dashboard warning symbol that looks like a battery. It could indicate a failing alternator, loose starter terminal or damaged cabling. However, if the light stays on while you’re driving, it’s probably due to your alternator belt which is responsible for charging your car’s battery as you drive.

What to do if your car battery is drained

The answer to this question entirely depends on why your battery is flat. If it’s old or faulty, you’ll need to replace the battery. It’s possible to do this at home with the right know-how and tools, but the quickest and safest option is to get a trained mechanic to do the job.

On the other hand, if your battery has been drained because you accidentally left a light on or the radio, you have two options. You can either jump start your car or purchase a car battery charger which plugs in at home.

How to jump start a car with a dead battery

If you really are stuck and can’t get hold of a mechanic to jump your car for you, here are the steps you need to take to get moving again.

Remember, you need to be extremely careful when carrying out the following steps as you’re dealing with high voltages.

If you see that the battery is cracked and is leaking acid, DO NOT ATTEMPT to jump-start the car as you will be putting yourself in serious danger.

Step 1

Park the car with the dead battery nose-to-nose or parallel to the another car and open the bonnet of each vehicle.

Step 2

Take the red positive jump lead, connect one end to the positive terminal on the dead battery (as shown below) and the other end to the positive node on the live battery on the other car.

Step 3

Do exactly the same using the black cable, attaching each end to the negative nodes.

Step 4

Start the engine of the rescue car and allow it to run for roughly 10 minutes. This will charge the dead battery of the other car.

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While the rescue car is still running, attempt to start the car. If it won’t ignite, leave the car for a few more minutes and try again. If this does not yield results in 30 minutes, there will likely be another problem preventing your car from starting.

Warning: Be careful around your battery

Do not hold both ends of the cables and attach to the battery, you’ll get the entire voltage of the car battery hitting you and that will be game over!

Don’t touch any of the metal terminals either, you’ll be French fried in no time…

What causes a car battery to die?

There are a number of reasons a battery could die, the most common are;

  • Leaving your headlights, interior lights or radio running for prolonged periods while your car is stationary.

  • If you don’t use your car for a long time, the battery will die as it won’t get charged by the engine.

  • The failure of the diode bridge or voltage regulator in the alternator. This is down to the fact that the alternator is responsible for charging the battery when the car is running so if it is malfunctioning, the battery will die.

  • If the temperature drops well below zero degrees, the battery could freeze!

Why won't my dead battery start with a jump?

If your battery is dead and it can't be jump started, then you will need to find a local car battery specialist garage or mechanic to diagnose the problem for you. It may be that you need a car battery replacement if your battery is beyond repair.

Find a mechanic to diagnose or fit your battery

It goes without saying, but make sure not to leave any of your electrics running for an extended amount of time when the car isn’t running, as this is the easiest thing you can do to avoid your car battery dying.

Remember, the easiest way to get you car moving again is to enlist the help of a professional.

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