Instructor at Üsküdar University's Occupational Health and Safety Department, Road and Traffic Safety Consultant Özgür Şener, evaluated recent electric vehicle fires, making important warnings ranging from processes that can lead to fire in lithium-ion batteries and charging safety, to precautions to be taken after an accident, and symptoms drivers should pay attention to.
“Electric cars are no longer the technology of the future, but of today”
Stating that one out of every four new cars sold worldwide is electric, Özgür Şener said, “Electric cars are no longer the technology of the future, but a part of today's transportation system. This rapid transformation brings new technologies, new usage habits, and new dangers to our agenda. One of these is the fire potential of lithium-ion batteries.”
How do fires start in lithium-ion batteries?
Özgür Şener noted that lithium-ion batteries, used in most electric cars, can store a high amount of energy in a small volume, emphasizing that this feature alone is not a cause of fire.
Özgür Şener stated that dangerous processes can begin if the battery operates outside its normal conditions, and said, “'Thermal runaway,' a significant safety concern in lithium-ion batteries, is defined as the cell entering an uncontrolled self-heating state. This process can lead to very high temperatures, gas release, particle ejection, smoke, and fire. The root cause of thermal runaway may be a fault within the cell or a condition that pushes the cell beyond its normal operating limits.”
Şener stated that internal short circuits, overcharging, external short circuits, and high or low temperatures can trigger thermal runaway, adding, “An important distinction must be made here. Thermal runaway is not the fire itself. However, it is a critical event that can turn into uncontrollable heating, fire, and other dangerous consequences.”
Accidents, short circuits, and manufacturing defects can increase risk
Özgür Şener emphasized that it is not accurate to talk about a single reason that increases the fire potential in electric vehicles, especially drawing attention to the importance of mechanical damage.
“Accidents and mechanical impact are significant causes,” said Şener, “Especially the crushing, puncturing, or physical damage to battery packs or cells can pave the way for failures such as internal short circuits. Electrical faults are also important. Internal or external short circuits, overcurrents, and problems in control systems can push the battery cell outside its normal operating conditions.”
Şener stated that manufacturing and design defects should also be considered, pointing out that some defects might remain “hidden” until they emerge during use.
“It is not correct to say that an aged battery necessarily means an increased fire risk”
Şener stated that incorrect generalizations can be made regarding battery aging, and said, “A general conclusion that the older a battery gets, the more likely it is to catch fire is not correct. There are numerous factors affecting battery lifespan. Aging should not be evaluated as a sole cause of fire, but rather in terms of changes that may occur in battery performance and electrical characteristics.”
“Extreme heat and low temperatures can also affect the battery's operating conditions,” said Şener, noting that battery management and thermal management systems are used in modern electric vehicles to control these conditions.
“Fast charging alone is not the cause of fire”
Şener pointed out that fast charging is one of the most curious topics for electric vehicle users, saying, “Fast charging alone is not the cause of fire. In modern electric vehicles, the charging process is controlled by the battery management system and the thermal management system. The crucial point is that charging should be carried out within the vehicle's design and the operating limits set by the manufacturer.”
Şener stated that overcharging is one of the conditions that can trigger thermal runaway, adding, “Incompatibility between the charger and the cell or battery, or an inadequately designed battery management system, can contribute to such conditions. Therefore, it is more accurate to evaluate the source of fire potential through inappropriate equipment, faulty systems, damaged batteries, or uncontrolled operating conditions, rather than defining it as ‘fast charging’ alone.”
Home charging should not be seen as “plugging in an ordinary device”
Şener emphasized that the fundamental approach to charging safety should be the use of equipment specified by the manufacturer and installed according to appropriate standards, stating that users should never use damaged, crushed, or worn charging cables and connectors.
Şener pointed out that if a vehicle or battery is damaged in a serious accident, the vehicle should not be recharged without expert assessment, and added that equipment not approved by the manufacturer or with uncertain safety features should also not be used.
Şener stated that the home charging infrastructure must be compatible with the electrical capacity required by the vehicle and charger, and warned, “If an unusual odor, excessive heat, smoke, sparks, or an error warning is observed during charging, the charging process should be safely terminated, and professional help should be sought.”
Şener said, “Instead of viewing home charging as 'plugging an ordinary electrical device into an outlet,' it should be seen as safely powering a high-power electric vehicle system.”
Fire may not occur immediately after an accident
Şener pointed out that one of the topics electric vehicle users should especially be aware of is the possibility of delayed fire after an accident, stating, “An electric vehicle may not burn immediately after an accident. The vehicle may even continue to operate. However, this does not mean that the high-voltage battery is undamaged.”
Şener stated that a physically damaged vehicle or high-voltage battery could generate toxic or flammable gases and fire either immediately or with a delay, and said that an uncontrolled rise in temperature and pressure in damaged battery cells could lead to thermal runaway, fire, and re-ignition.
Şener also drew attention to the continued risk of electric shock and re-ignition due to residual electrical energy in the battery, warning, “Therefore, after a serious accident, the approach 'The vehicle is running, so the battery is safe' is incorrect.”
Approximately 15-meter warning for damaged electric vehicles
Özgür Şener stated that it is recommended to keep severely damaged lithium-ion battery vehicles at least 15 meters away from buildings, other vehicles, or flammable materials.
Şener emphasized that this distance should not be misinterpreted, stating, “This distance should not be considered as a universal 'safe distance' applicable to everyone during an active fire, but rather as a recommendation for safely storing a damaged vehicle after an incident.”
Pay attention to odors, smoke, hissing, and bubbling sounds!
Şener said that it might not be possible for drivers to definitively diagnose thermal runaway beforehand, and stated that caution should be exercised when “unusual heating, a burning or chemical smell, smoke or vapor, battery system warnings, unusual behavior during charging, sparks, and hissing, bubbling or similar sounds coming from the battery area” are observed.
“It is not correct to say that an electric vehicle fire cannot be extinguished”
Şener stated that electric vehicle fires should not be evaluated in exactly the same way as gasoline or diesel vehicle fires, adding, “This situation can create different dangers during a fire: electric shock due to high voltage, thermal runaway, re-ignition of cells, and the energy within the battery potentially continuing for a long time are some of these.”
Şener noted that the approach stating “an electric vehicle fire cannot be extinguished” is also incorrect, adding, “A more accurate statement is: In a battery fire, extinguishing only the visible flame may not be sufficient. It may be necessary to prevent the cells inside the battery from reheating and to cool the battery.”
Şener stated that large and continuous amounts of water may be needed for cooling in high-voltage lithium-ion battery fires, and pointed out that even if the fire appears to be extinguished, the possibility of delayed ignition or re-ignition may persist.
“The driver's duty is not to extinguish the fire, but to ensure life safety”
Şener emphasized that small and portable classic fire extinguishers may not always be sufficient to control a large fire involving the battery itself, stating, “The critical point here is: For the driver, the escape and life safety strategy is important, not the fire extinguishing strategy. Professional extinguishing is the job of trained firefighter teams.”
In battery fires, there is a risk not only of flame but also of toxic gas
Şener stated that smoke and gases also pose a serious danger in battery fires, and explained that gases released during thermal runaway and fire, as well as combustion products, can be toxic and/or flammable.
Şener emphasized that occupants of the vehicle and people in the vicinity should not inhale smoke, should not approach the vehicle unnecessarily, and should not touch high-voltage cables or the battery pack, underlining that fire should not be personally intervened with. Şener also added that emergency response teams must be informed if the vehicle is electric or hybrid.
“The goal is not to declare electric vehicles dangerous”
Özgür Şener stated that the transformation in electric vehicle technologies also brings a new understanding of risk management, saying, “Our aim here should neither be to declare electric vehicles 'dangerous' nor to ignore the dangers created by technology. The important thing is to recognize the danger, know the conditions that can increase the fire potential, consider the possibility of delayed incidents after an accident, ensure charging safety, and develop correct intervention behavior.”
Şener noted that the basic approach of occupational health and safety also applies to road and traffic safety, and concluded his words as follows:
“Instead of controlling the danger after it occurs, it is to define it beforehand and manage the risk before it materializes. A safe future for electric vehicles will be possible not only with larger batteries and faster charging systems; but with safe design, proper charging infrastructure, conscious users, trained intervention teams, and a strong safety culture.”
