EV fires do not behave like the fires most Australians have been taught to manage. The chemistry is different. The timeline is different. The risks during and after the event are different. Understanding what actually happens inside a lithium-ion battery fire — and when — is the foundation of a rational, effective response.

Stage 0: The Precursor (Minutes to Days Before)

Before visible fire, a failing battery often produces signals. Internal cell damage — from physical impact, overcharging, manufacturing defects, or age-related degradation — begins generating internal heat. The battery may feel warmer than usual during charging. Minor gas production may produce a faint chemical odour. Physical changes in the battery casing may become visible. This is the window in which an alert owner can prevent the fire entirely — a battery showing abnormal heat or any physical change should be removed from service immediately and stored in a lithium-ion containment bag.

Stage 1: Thermal Runaway Initiation (Seconds to Minutes)

Once a cell reaches a critical internal temperature — typically 80 to 150 degrees Celsius depending on battery chemistry — an exothermic chain reaction begins. The electrolyte breaks down, producing flammable gases. Heat propagates to adjacent cells, which begin their own decomposition. Gas pressure within the battery enclosure builds rapidly. At this stage, evacuation should already be complete. If it is not, evacuate immediately.

Stage 2: Venting and Smoke (Seconds)

As internal gas pressure exceeds the structural limits of the battery casing, venting occurs. The gases released are a toxic cocktail including hydrogen fluoride, carbon monoxide, and various volatile organic compounds — all highly flammable. Visible smoke begins at this stage, initially white or light grey, potentially darkening as more of the battery chemistry breaks down. The smoke itself is toxic; being in the vicinity without respiratory protection is dangerous.

Stage 3: Ignition (Instantaneous)

The hot flammable gases vented from the battery ignite. The resulting fire is extremely hot and fast-spreading. This is the stage at which a deployed EV fire blanket becomes critical. By containing the fire and capturing gases, a blanket slows propagation to surrounding vehicles, structures, and materials while emergency services are en route.

Stage 4: Sustained Burn

Unlike a petrol fire which depends on external oxygen, an EV battery fire can sustain itself from the oxidiser within the battery chemistry. It can burn for hours. An enormous volume of water — often thousands of litres for a full EV battery pack — is required to bring and maintain cell temperatures below the thermal runaway threshold. During this stage, the battery may appear to be extinguished while still generating internal heat above the re-ignition threshold.

Stage 5: Re-ignition Risk (Up to 24 Hours)

A battery fire that appears extinguished can re-ignite. This is a well-documented phenomenon that has claimed the lives of first responders and bystanders who assumed the danger had passed. Re-ignition can occur up to 24 hours after initial suppression. A vehicle or battery involved in a thermal event must be treated as a re-ignition hazard until professionally assessed.

The Right Response, Stage by Stage

Stage 0: Remove the battery from service and secure it in a containment bag. Stage 1: Evacuate and call 000. Stages 2 & 3: Deploy an EV fire blanket if safe to do so from a distance. Stages 4 & 5: Leave it entirely to emergency services. Do not re-enter until cleared by fire services. Never assume it is safe because the flames are gone.