Why your car is more likely to break down on a Monday

Moving Well | Tianna Nadalin | Posted on 08 December 2019

RACV data reveals car batteries don’t like Mondays and summer is the real battery killer.

Get your jumper leads ready. New RACV data reveals your car battery is most likely to fail on the first day of the working week. In the past 12 months, RACV Emergency Roadside Assistance patrols replaced more than 105,000 batteries across Victoria, with almost 18,000 of those sold to members on a Monday. And there’s a simple explanation for why your battery feels a bit flat on Mondays, too.

Man with car bonnet open putting jumper leads on car battery

“Car batteries work best when they’re used regularly, so when you park your car for an extended period, usually on weekends, that’s when problems are more likely to occur,” RACV’s manager of vehicle engineering, Michael Case, explains.    

“In a two-car household for example, one vehicle may not be driven on the weekend, so on Monday morning a battery fault can occur.”         

Michael also dispels the myth that winter’s chill is worse for car batteries, saying summer heat is the real battery killer.

“Like humans, your car battery can also become dehydrated over the hot summer months,” he says. “This is called heat deterioration. High temperatures can evaporate a battery’s vital liquids, or electrolytes, weakening its charge and reducing its life.”

He says higher temperatures also accelerate the internal chemistry of the battery, which degrades the plates more rapidly and, in turn, reduces the ability of the battery to start the vehicle.

If your battery is damaged or weakened over the summer, it will reduce its functionality when the cool weather hits.


“If a battery gets hot enough, its internal components corrode and weaken how much power the battery has,” Michael says. “Winter starting requires about double the energy of summer starting, so if your battery is damaged or weakened over the summer, it will reduce its functionality when the cool weather hits.”   

Michael says motorists can do a few simple things to extend the life of their vehicle’s battery to avoid battery burnouts.

“Make sure your headlights and interior lights are off before leaving your car and ensure all the doors are closed properly,” he says.     

“Most new vehicles come with sensors and warning devices to alert you if you leave the headlights on, some even turn off automatically.”

RACV recommends motorists check their car battery regularly. If unsure of your battery condition take your car to a licensed vehicle workshop for a safety check.     

If you need RACV Emergency Roadside Assistance call 13 11 11. It’s available 24/7 Australia-wide. 

RACV is there for you 24/7 whenever you're in need of help out on the road. We're always just a phone call away