How does cold weather affect your car battery?

When you turn the ignition key to start your car, everything depends on the battery hidden somewhere in your car's engine compartment. Car batteries usually don't have to work very hard in warm weather, but when wintery conditions arrive, the engine is harder to turn over, so the battery has to work harder.

With over 400,000 flat battery callouts responded to last year, our NRMA roadside assistance and battery technicians have seen it all so you can trust our expertise to get you back on the road if you need us. There are, however, some things you can do to prevent issues and extend your battery's life.

Temperature plays an important role in the performance of your battery

Most batteries in new cars should last three years on average and a cold snap will sort out the good from the bad!

Inside the typical lead acid battery are lead plates in electrolyte liquid which creates an electro-chemical reaction to produce a charge to the battery terminals. Heat accelerates this chemical activity but also speeds up the internal corrosion with the cells which in turn reduces the lifespan of your battery.

This is particularly true of batteries that repeatedly reach high internal temperatures, and once capacity has been damaged by heat, it can’t be restored. But just as heat speeds up chemical reactions, cold temperatures slow them down. That’s why you might feel your battery can become sluggish in winter, even though its state of charge may remain unchanged.

At colder temperatures, the battery’s ability to provide sufficient power to start and run a vehicle is diminished. Automotive batteries are rated in CCA (Cold-Cranking Amperage). This is the amount of current a battery can deliver for 30 seconds at -18 C without dropping to a specified cut-off voltage. A fully charged lead-acid battery can survive up to –50 C, but a battery with a low state of charge can freeze at –1 C. When the water in a battery freezes it expands and can cause irreparable damage to the cells.

Learn how to maintain your car battery

We recommend that car owners start paying close attention to their batteries after three years of installation. If your battery is starting to go, the first thing you'll probably notice is that the car sounds sluggish when trying to start. This is a major warning sign that shouldn't be ignored.

If you hear sluggish sounds when you start up your car, do not immediately assume that the battery needs replacing. Check that the battery connections are tight and that the wires are not broken or disconnected. Also ensure that your terminals are clean - you can get them cleaned regularly during every major service so ask your mechanic. 

If your battery has caps, remove them and check that the fluid inside is about 5mm above the plates, or between the levels as indicated on the battery case. If low, top up with deionised water and avoid overfilling. Mop up any spillage. Some batteries are permanently sealed and do not require maintenance, so you won't be able to check the fluid if this is the case.

If you are in any doubt, contact the team at NRMA Batteries and we can help.

Get a free battery health check

Regular testing of your car battery can help to catch potential issues early, not just when symptoms arise. Our technicians at the NRMA recommend testing your battery once or twice a year to prevent unexpected failures. If you're still noticing signs of a low battery such as difficulty starting your vehicle or dashboard lights coming on unexpectedly even after doing the above checks, consider getting expert assistance to diagnose any underlying issues. The NRMA offers free battery health checks for Members to assess the condition of your battery, ensuring you can identify battery issues before they become worse, providing you with peace of mind.

Know the current health status of your car battery with a battery health check. Credit: The NRMA

In less than 10 minutes, our experts can visit you at your preferred time to diagnose any battery issues proactively. You'll receive a printout of the test results, providing clarity on your battery's health and lifetime expectancy. If any problems are detected during the test, the specialist will explain your options so you can make informed decisions. There's absolutely no obligation to purchase a new battery after the health check.

Should you need a replacement battery, we carry an extensive range of high performance battery options, all backed by nationwide warranties, and we responsibly recycle your old battery for you. Don't let winter catch you off guard—stay proactive with our expert services to keep your car running smoothly throughout every season.