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How hot weather affects battery performance – and how to prevent damage

How hot weather affects battery performance – and how to prevent damage

If our car batteries had it their way, it would be a clear, dry, and beautiful Spring day all year round. Relatable! This is because extreme temperatures, whether cold or hot, are hard on car batteries. Although they’re generally designed to withstand severe conditions, car batteries vary greatly in temperature resilience from brand to brand, and not all can perform well in a scorching Australian summer. So what happens when you combine a car battery + hot weather? Why do some car batteries fail prematurely in hot weather? And most importantly, is there a way to stop it from happening?

Car battery + hot weather =…?

To understand how hot weather degrades car batteries, we’ve got to break it down to the chemical level. 


Basically, batteries contain a form of acid, which is naturally corrosive. That corrosive effect increases when the battery acid gets warmer. So, when the weather is hot, car batteries can start to corrode internally due to overheated battery acid. Soon, this causes sulphation of the plates, which inhibits the flow of electric current.

Water loss

Car batteries can also fail in hot weather due to water loss. While water loss is a normal side effect of the battery’s functioning, that water loss is accelerated rapidly as the under-bonnet temperature increases. 

Battery stratification

Hot weather isn’t the only thing that can cause overheating. Lots of driving during rush hour can damage your battery in the same way a hot summer day can. Driving home in bumper-to-bumper traffic keeps the engine hot for longer. 

As your traffic-induced frustration rises, so does the temperature under your bonnet. This can cause battery acid stratification: where a heavy concentration of acid settles to the bottom of the case.

Protecting your car battery from heat damage

Now that we’ve covered how hot weather can damage your battery, let’s talk about how you can stop that from happening. Here are our mechanics’ top tips on protecting your car battery.

  • Choose a brand that is built for the Australian climate
  • Avoid driving in gridlock conditions if you can
  • Avoid extremely long drives on hot days
  • Remove and safely store your battery somewhere cool if you’re not using your car for a while
  • Check your coolant level and refill if necessary


Having trouble with your car battery, or just want to check up on it ahead of a long drive? We’re here to help. Drop in and see one of our experienced mechanics at your local service centre.

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