A man helps a woman jump start her battery in snowy weather.
Vehicles

Warning signs for car batteries in winter

Winter is when your car is most prone to battery failure. Here’s why, and how to recognise an issue before you get stranded somewhere.

By Shell on Jul. 14, 2022

It's a familiar winter experience. You go out to start your car on a chilly morning, turn the key… and nothing happens.
A dead car battery always seems to happen in winter, but why? And how can you pick the warning signs so you can replace it before you're left stranded? Here, we break it all down.

Car batteries – the basics

Your average battery is made up of separate cells containing lead plates submerged in a liquid/gel acid solution and the chemical reaction between these materials (or electrolysis) produces electricity. More recently, lithium technology has become a common medium.
This electricity is used to start the engine and power electrical components when the engine is off. Once the engine is running, the alternator powers the electrical system, as well as recharging the battery.

Why is winter tough on a battery?

Cooler temperatures slow the chemical process in a battery, compromising its ability to hold charge. At the same time, the battery and electrical system are worked harder as we flick on lights, crank the heater, etc. Cold temperatures thicken engine oil too, increasing the power needed to crank it into life.
Batteries also lose performance with age, so an older battery will suffer more in cool temperatures than a newer one. All of this is why winter battery failure is so common. When that first cold snap hits, a battery that had just enough performance in milder weather is now that critically bit weaker.

The warning signs

Batteries tend to degrade progressively, so you should get some warning when yours is on the way out.
Here’s what to look out for:

  • Slow cranking
    Cranking an engine works a battery hard, so if the usual starting chatter seems sluggish, a no-start situation is the likely next step. This issue can also be due to a failing starter motor or other electrical-system issue, so don't put off seeking professional diagnosis.

  • Warning lights
    Electrical systems in newer cars have sophisticated management capabilities and can even detect a battery with low charge. When that happens, a battery or electrical-system warning light will be triggered. In an older car it might be a more general ‘check engine’ warning. Whatever warning flashes up on the dash, further investigation is needed.

  • Electrical bugs
    As well as being able to detect a failing battery, newer cars can take steps to preserve their power such as shutting down non-vital functions. If your stereo or other electrical gadgets mysteriously stop working or work only intermittently, a failing battery or other electrical-system issues could be the culprit.

  • Damaged battery case
    Extreme heat, cold or electrical-system issues can damage a battery, causing it to swell, leak, vent gases or, in some cases, even explode. If you notice swelling, cracks or leaks from the case or funny smells, it'll need to be replaced, even if it seems to be performing fine now.

  • Old age
    All batteries degrade and need to be replaced, generally within three to five years, though they can also last longer or fail sooner. If yours is in that age range and you don't want to find out the hard way, book in a test.

If your car is suffering from any of these issues, book a visit to your mechanic or local battery specialist – they can test your battery and accurately diagnose its condition.

Disclaimer

Viva Energy Australia Pty Ltd (“Viva Energy”) has compiled the above article for your general information and to use as a general reference. Whilst all reasonable care has been taken by Viva Energy in compiling this article, Viva Energy does not warrant or represent that the information in the article is free from errors or omissions or is suitable for your intended use.