Why Do Car Batteries Die? - WhoCanFixMyCar

There are several reasons why your car battery can die, both with and without warning. This guide discusses what they are and, when possible, how to avoid them.

In a nutshell: Car batteries can die due to electrical components that have been left on, corroded or loose connections, charging problems, weather conditions, a parasitic draw, and too many short journeys.

Why can a car battery die?

There are many reasons why your car battery might die.

1. Leaving your headlights on

One of the most common reasons for battery failure is leaving your headlights on while the car is switched off, which drains the battery. This error is more common in older vehicles because they do not warn you if the lights are still on as you exit.

2. Corroded or loose battery connections

A visual inspection is the best way to notice that your car battery terminal has become corroded, and you may see a blue, green or white powdery substance leaking from your battery.

Corroded batteries can prevent the starter motor from drawing a current, ultimately causing your car battery to die.

3. Leaving your car stereo on

Similarly to headlights, leaving your stereo on could also be the reason why your car battery dies. Though, on average, it will take two to three hours for your battery to die when the radio has been left on, cars with a weak battery terminal may be drained much quicker.

4. Charging problems

Problems with the alternator can result in a dead battery, though fortunately, you are likely to notice some warning signs before this happens. Here are five signs of a faulty alternator.

5. Weather conditions

Whether it’s icy or extremely hot conditions that your car battery is subjected to, the climate can certainly be a reason your car battery can die. However, this is more likely to affect already weakened car batteries.

6. A parasitic draw

A parasitic draw is an electrical component that continues drawing power even when it shouldn't, resulting in a flat battery. This can happen due to a wiring issue, short circuit or stuck relay. If your battery keeps failing and there's no obvious reason why, it may be due to a parasitic draw.

7. Too many short journeys

When you only use your car for short journeys, the battery doesn't have enough time to recharge, so eventually, it will go flat. Driving for at least 30 minutes once a week should be enough to keep your battery topped up.

Frequently asked questions

Why do car batteries die in the cold?

Unfortunately, it is common for car batteries to die in cold conditions. Car batteries produce less electrical current when they’re cold, and this can result in your battery struggling or dying completely.

Why do car batteries die when not used?

The longer that your car is not used, the longer the battery is not charging. Car batteries store their charge when not in use and begin to charge themselves as the car is driven. However, over time, batteries will naturally discharge themselves and ultimately die.

The best way to avoid this happening is to make sure that your engine is running at least once a week.

Can you drive a car with a corroded battery?

It is not safe to drive a car with a corroded or leaking battery. The sulphuric acid that can be found when your car battery leaks can be dangerous for both you and your vehicle.

Can a car battery die while idling?

Yes, car batteries can die while idling. When your car is idling, the engine and alternator run together slowly. However, if the alternator fails, the electrical load needed to power your car will eventually drain the battery

Can a car battery die while driving?

Damaged or faulty car batteries can die while you drive. If your battery is weak and unable to retain enough charge to run, it will continue to die on you.

Has your car battery died? FixMyCar's trusted garage network can get you back on the road in no time.

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