Recently, the world has witnessed strong development of Electric Cars. Meanwhile, in Vietnam, electric cars are still new with only a few representatives such as VinFast VF e34 and VF8, Porsche Taycan, Audi E-tron, Hyundai Ioniq 5 and some new Chinese electric car models are joining the market like Wuling Hongguang Mini EV.
Aside from the range and charging time, the risk of Fire is also one of the concerns when it comes to electric cars. Especially in the current context, when the fire hazard in narrow alleys with dense population, fire trucks have difficulty getting in, causing serious consequences to people and property. The question is, are electric cars more prone to catching fire than gasoline cars? Which type of vehicle is more likely to pose a fire hazard?
Are electric cars more likely to catch fire than gasoline cars?
The main reason for electric car fires is the battery. On the other hand, gasoline cars have many causes such as electrical component failures, fuel/liquid leaks, exhaust systems overloading, overheating engines, etc. Therefore, compared to the fire risk of traditional gasoline cars, electric cars are much lower. In fact, the number of electric cars catching fire is also quite low.
Electric cars have a much lower risk of catching fire than gasoline/diesel cars.
According to the National Transportation Safety Board (NTSB) data, there were a total of 16,051 hybrid cars catching fire in accidents. The corresponding number for gasoline cars was 199,533 cases. Meanwhile, there were only 52 cases of electric cars catching fire.
Tesla asserts that gasoline cars have an 11 times higher fire incidence rate compared to their electric cars. This company states that the best comparison rate is the fire rate per 1.6 billion kilometers traveled. The electric car manufacturer claims that 300,000 Tesla vehicles on the road have traveled a total of 12 billion kilometers and there have been around 40 reported fire cases. This figure is equivalent to 5 fire incidents per 1.6 billion kilometers traveled. Meanwhile, gasoline cars have a ratio of 55 fire incidents per 1.6 billion kilometers traveled.
How do lithium-ion batteries in electric cars catch fire?
Lithium-ion batteries in electric cars are highly prone to catching fire due to their component structure. However, car manufacturers have methods to prevent the fire and explosion of lithium-ion batteries. A lithium-ion battery consists of 4 main components: the cathode, the anode, the electrolyte solution, and the separator.
Fires in lithium-ion battery packs usually occur due to short-circuits in one or more battery cells, generating high heat. If the battery of an electric car is damaged due to collision, fire, or water intrusion, a short circuit may occur. This causes the battery cells to release energy and increase in temperature, leading to thermal runaway. This chain reaction can cause the battery to fail or explode, resulting in a fire and an outbreak.
Illustration of the battery fire process in electric cars, from short-circuit, to thermal runaway, ignition, and spreading
Even in cases where an electric car is submerged in water (flooded), contaminated substances, or salt, these can cause the battery to short-circuit, especially after the water recedes. The movements of an electric car or a damaged battery, for example, when the car is being towed, also have the risk of causing a short circuit.
Heat generated from burning, the thermal runaway of an adjacent battery cell, or a short circuit can melt the foam barrier between the cathode and anode of a battery cell, causing that battery cell to continue to generate heat and release flammable gas. As a result, the entire battery pack can catch fire. “Heat can transfer to adjacent battery cells, becoming a chain reaction,” Mr. Barth explained.
The biggest difference compared to gasoline is the time it takes for an electric car to catch fire. Gasoline fires almost immediately when gasoline catches a spark or flame and spreads quickly. On the other hand, a battery fire usually requires a period of time to accumulate enough heat before igniting. In some cases, this delay is a good thing because the occupants of the car can escape before the fire occurs. In some other cases, even though the battery cells have been extinguished, there is still a risk of re-ignition after many hours or even days, making it difficult for rescue and repair work.
Illustration of a Lithium-ion battery pack in a Tesla car
Electric car fires are more intense and difficult to extinguish than gasoline fires
As mentioned above, electric cars are less prone to fire than vehicles using traditional gasoline engines. However, once on fire, lithium-ion batteries in electric cars are much harder to extinguish. Currently, there are no effective and rapid fire extinguishing methods for electric car fires.
The biggest difference compared to gasoline is that electric cars cannot be extinguished with regular fire-fighting foam. Instead, firefighters need to cool down the battery of the electric car to prevent fire and thermal runaway.
“Lithium-ion batteries produce their own heat and oxygen”, said Andrew Klock, Director of Products and Development at the International Association of Fire Chiefs. Therefore, shutting off the external oxygen supply also does not stop the fire, and foam spray has no effect. To extinguish an electric car fire, firefighters have to spray a large amount of water onto the battery pack to cool it down.
Firefighters extinguishing a fire caused by a Tesla electric car
Most of the batteries in electric cars are located underneath the vehicle, so spraying water on the body or engine compartment has no effect. “You need to spray water underneath the vehicle“, added Mr. Klock.
According to the National Fire Protection Association, extinguishing an electric car fire with water requires more than 110,000 liters of water, about 20-25 times more than a gasoline car, and takes more time.
Above are the most basic knowledge about electric car batteries, the fire-causing principles, and the fire extinguishing methods. It can be seen that both electric cars and gasoline cars inherently have a significant fire and explosion risk. Users need to pay attention to ensure the safety of themselves, their families, and society.
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