Spontaneous car fires. Is your smartphone or laptop to blame? (consumer advice)

In 2024, there were nearly three thousand unexplained spontaneous car fires (excluding EVs and Hybrids) in NSW alone.

Fire Departments do not keep granular statistics on car fire causes. They increasingly suspect lithium-ion smartphones and laptops are a significant cause, especially when the fire starts inside a parked car.

Why the significant increase in spontaneous car fires?

The RACV conducted temperature tests in parked cars. It found that when the ambient outside temperature is 30°, the interior temperature reaches over 70° in scant minutes.

Stamford University USA said, “The cars’ colour does not significantly impact interior temperature increases when the car is parked in direct sunlight. The temperature inside a car increases because of the greenhouse effect.”

The greenhouse effect is caused by the glass acting as a one-way conductor. It lets in the harmful long wavelengths that cause heat but not vice versa.

It has long been known that children and pets should never be left in parked cars, even for a few minutes. But the message about smartphones and laptops has not begun to sink in.

Why single out smartphones and laptops?

The warning should apply to any rechargeable lithium-ion-powered device, including battery power banks, tools, cordless vacuums, cleaning devices, toys, heating coffee cups, GPS, dashcams, and more.

Read Is there a safe way to charge Lithium-ion batteries? (guide).

Every lithium-ion battery maker publishes its operational parameters. While these vary by a few degrees, Lithium-ion operates best between 15-35° and is generally non-functional from 50-60°. The ARC Training Centre for Fire Safety found that typical Lithium-ion batteries can spontaneously combust at this threshold.

There is a growing trend of laptop batteries overheating, catching fire, and exploding into flames. In recent years, Apple, HP, Toshiba, and Dell have recalled millions of lithium-ion laptop batteries due to fire hazards. Fire departments find it hard to identify these as the cause of fire as they are usually on car seats that have been completely burnt out.

What can you do?

Simple: Remove any lithium-ion devices from your car when parked in the sun.

Check if your GPS or dashcam has a supercapacitor instead of a lithium-ion battery. You can safely leave them in the car.

If you must leave them, get an insulating box. An Esky can keep the devices at the car’s original ambient temperature without ice for a couple of hours.

Solar-powered window ventilation fans can help by sucking the heat out. But these have proven to only lower the car’s internal temperature by a few scant degrees. Dashboard fans do nothing.

It is a fallacy that window tinting or windscreen shades work. The greenhouse effect is often worse as these do not let the heat out.

Our insurance expert said that where it can be proven that a lithium-ion device was responsible, the claim will likely be denied as these are classified as dangerous goods for transport.