Fire Safety and Electric Vehicles

Main Reasons for Fires in Electric Vehicles (EVs)

While most of us consider Electric Vehicles (EVs) as inherently safer than traditional petrol or diesel powered cars, they are not immune to fires. Here are some of the primary reasons that can cause fires in EVs:

1. Battery Cell Failure

• Thermal Runaway: The most common cause of EV fires is “Thermal Runaway”. This is a condition where a single battery cell overheats and in turn, causes adjacent battery cells to overheat as well, leading to a chain reaction; resulting in fire.
• Manufacturing Defects: Defects in the manufacturing process of battery cells can increase the risk of thermal runaway. Adhering to Quality Standards (during design and manufacturing stage) play the most crucial role in avoiding such defects.

2. External Factors

• Accidents and Collisions: High-speed collisions or severe physical impact(s) can damage the battery pack, thereby leading to fire.
• Intentional Damage: Though observed relatively rarely, malicious acts like vandalism or arson also can cause fires in EVs.

3. Charging Issues

• Charging Faults: Faulty charging equipment or improper charging practices do increase the risk of fires.
• Overcharging: Overcharging the battery pack beyond its rated capacity can lead to thermal runaway. EV users must adhere to OEM recommendations to avoid such issues.

4. Thermal Management Issues

• Cooling System Failures: Sub-optimal functioning or malfunctions in the EV’s cooling system also can cause the battery pack to overheat, increasing the risk of fire hazard.
• Thermal Runaway Propagation: Ineffective / inefficient thermal management systems can allow thermal runaway to spread rapidly within the battery pack. This must be tested thoroughly at the design stage itself and there are no short-cuts in this.

5. Manufacturing Defects

• Wiring Issues: Faulty wiring or connections within the EV can lead to electrical shorts and fires. Process adherence, proper training, automation to the extent possible (to avoid human effort factor) are some of the most important aspects the EV manufacturers must follow.
• Component Failures: Defects in other components, such as the motor or inverter, can also contribute to fires. Regular inspections, QC of supply-chain partners, collaborative training programs would go a long way to ensure such issues.

We come across relatively lower incidents of EV fires, compared to fires in ICE / Petrol-powered vehicles in India; which is primarily due to the much lower number of EVs in use compared to traditional ICE vehicles. Given the high-standard manufacturing and process driven industry that we have seen so far in EV industry, we will continue to experience lesser number of fire incidents involving EVs even after the penetration/adaptation of EVs in India increases multi-fold.

EV battery fires pose unique challenges to the firefighters because of several factors

We must keep in mind that fire hazards in EVs can be reduced through right engineering and quality control. However, when they do occur, EV battery fires are more difficult to extinguish due to the high-voltage electrical systems, the potential for rapid thermal propagation within the battery pack and the chemical composition of the batteries.

1. High Energy Density: EV batteries store a significant amount of energy in a compact space. This high energy density can lead to intense fires that are difficult to contain or tend to from close range.
2. Rapid Thermal Propagation: Once a fire starts in an EV battery pack, it spreads rapidly due to the close proximity of individual battery cells. This makes it difficult to isolate the fire and prevent it from spreading to other parts of the battery pack within EV.
3. Water-Based Extinguishers Ineffective: Traditional water-based extinguishers used by firefighters are often ineffective against EV battery fires. Water can cause a short circuit or even intensify the fire by resulting/forming steam.
4. Toxic Fumes: Burning lithium-ion batteries releases toxic fumes, such as Hydrogen-fluoride and Hydrogen-cyanide, which is harmful to firefighters and to the environment.
5. Re-ignition Risk: Even after a fire is initially extinguished, there is a real risk of re-ignition due to the high energy density of the battery pack and residue heat that may be contained within the damaged battery pack.

To effectively extinguish EV battery fires, firefighters would need to use specialized techniques and equipment, such as foam extinguishers designed particularly for lithium-ion batteries combined with cooling methods to reduce the temperature of the battery pack and prevent re-ignition.

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Let’s quickly compare EV Battery Fires to ICE Vehicle Fires

EV Battery Fires

• Intense Heat: EV batteries generate extremely high temperatures when involved in a fire, often surpassing those of traditional petrol/diesel based vehicles (ICE).
• Rapid Thermal Propagation: As stated earlier, fires in EV batteries spread quickly due to the close proximity of individual cells, making them difficult to contain.
• Water-Based Extinguishers Are Ineffective: Traditional water-based extinguishers are not effective against EV battery fires, as water can cause short circuits or intensify the flames.
• Toxic Fumes: As stated earlier, burning lithium-ion batteries releases toxic fumes, such as Hydrogen-fluoride and Hydrogen-cyanide.
• Re-ignition Risk: Even after being extinguished, EV battery fires can reignite due to the high energy density of the battery pack.

ICE Vehicle Fires

• Fuel Tank Fires: The most common cause of fires in ICE vehicles is fuel tank leaks or ruptures caused by accidents or done on purpose.
• Electrical Short-circuits: Electrical short-circuits can also ignite fires in ICE vehicles, especially in older models.
• Overheating: Overheating of the engine or brakes can lead to fires in some cases.
• External Factors: Accidents, vandalism or other external factors can also cause fires in ICE vehicles.

Key Differences in fires of Electric Vehicle and ICE Vehicle

• Intensity: EV battery fires tend to be more intense and difficult to extinguish due to the high energy density of the batteries.
• Toxic Fumes: EV fires can release toxic fumes, while ICE vehicle fires typically release comparatively less harmful substances.
• Re-ignition Risk: EV battery fires have a higher risk of re-ignition due to the stored energy in the battery pack.

Overall, while both EV and ICE vehicles can experience fires, EV battery fires present unique challenges due to their high energy density, rapid thermal propagation and the potential for toxic emissions.

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It is important for firefighters and emergency responders to be aware of these differences and have specialized equipment and training to handle EV fires effectively.        

Imparting proper training of the firefighting personnel from the Fire Department as well as educating the House-keeping staff deployed at offices/high-rise residential complexes on the DOs and DON’Ts would be the key to ensure right steps are taken at right time to avoid damage to property and save precious lives.

Be it EV or ICE, if we follow right steps, most untoward incidents can be avoided.

Please follow best practices, be vigilant and stay safe.

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