Causes of EV Fires and How to avoid Them:In-Depth Analysis
In recent years, with the rapid increase in the number of new energy vehicles (NEVs), their safety issues—especially spontaneous combustion—have attracted growing public attention.
Although statistics show that the overall fire rate of new energy vehicles is actually lower than that of traditional fuel vehicles, battery fires are more dangerous due to their intense heat, difficulty in extinguishing, tendency to reignite, and emission of toxic gases. So, what are the real causes of EV fires? Under what conditions are they most likely to occur? And how can we effectively prevent them?
This article takes a deep dive into the causes of EV fires and provides practical prevention strategies to help users better understand the safety characteristics of electric vehicles and ensure safer driving.
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EV Fire Incidents vs. Fuel Vehicles: What the Data Really Shows
Before exploring the causes of EV fires, it’s important to clarify one key point: Are EVs really more likely to catch fire than fuel vehicles?According to data from China’s fire authorities and industry organizations over the past three years:
- In 2021, the fire rate of new energy vehicles was 1.85 per 10,000 vehicles;
- By 2023, it had dropped to 0.96 per 10,000 vehicles;
- In the same period, fuel vehicles had a fire rate of about 1.5 per 10,000 vehicles.
- In Norway, where new energy vehicles are very popular, the fire rate of fuel vehicles is even 4-5 times that of electric vehicles.
This shows that, from a probability perspective, new energy vehicles are not “more likely” to catch fire. However, when they do occur, battery fires are more hazardous, featuring:
- Combustion temperatures above 800°C (1470°F)
- Emission of hydrogen fluoride (HF) and hydrogen cyanide (HCN)
- High risk of reignition, even after being extinguished
- Extremely short window for escape—only seconds between thermal runaway and visible flames.
Therefore, while EV fire incidents are rare, their severity and visibility make them highly concerning.
Main Cause of EV Fires: Battery Thermal Runaway
Analysis of numerous EV fire cases shows that nearly all of them can be traced back to one underlying mechanism — battery thermal runaway.
What Is Thermal Runaway?
Thermal runaway occurs when a battery’s internal temperature rises uncontrollably due to internal short circuits, overcharging, overheating, or mechanical damage. This triggers a chain reaction of exothermic (heat-generating) chemical reactions, further accelerating the temperature increase until ignition or explosion occurs. It’s worth noting that thermal runaway ≠ inevitable fire. Modern EV batteries can experience thermal runaway without catching fire, depending on the battery pack design and thermal management system.
Key Factors Leading to Battery Thermal Runaway
Battery Quality Issues
Battery quality directly affects EV safety. Defective or poorly manufactured batteries are more prone to failure.
- BMS (Battery Management System) failure
The BMS(Battery Management System) is the core control unit of the battery pack, responsible for battery status monitoring, safety protection, and performance optimization. A BMS failure or software vulnerability can lead to battery overcharge or overdischarge, potentially triggering thermal runaway.
For example, in 2021, a certain brand of electric vehicle overcharged its battery due to a BMS software vulnerability, causing the separator to melt and short-circuit, ultimately leading to spontaneous combustion.
- Defective battery cells
The lithium-ion battery production process involves dozens of precision steps, each requiring strict quality control. Defects such as metallic foreign matter, electrode burrs, or damaged diaphragms within the battery cell can trigger an internal short circuit, releasing significant heat and ultimately leading to thermal runaway.
For example, an investigation into a 2023 spontaneous combustion incident in a certain vehicle revealed the presence of metallic foreign matter within the battery cell, triggering a chain reaction of short circuits.
Thermal Management System Failure
The thermal management system is key to ensuring the normal operating temperature of the battery. If the thermal management system fails, resulting in insufficient heat dissipation from the battery, thermal runaway may occur.
- Coolant leakage: Coolant pipe ruptures or water pump failures can lead to insufficient heat dissipation from the battery pack. For example, in 2023, a certain vehicle model spontaneously combusted while driving in hot weather due to a clogged battery coolant pump, causing local temperatures to exceed 200°C.
- Blocked air cooling: The cooling fan is faulty or the air inlet is blocked by foreign objects, affecting air circulation.
- Faulty thermal control software: Cooling is not initiated in time when the battery temperature is too high.
Battery Aging and Degradation
Over time, battery capacity decreases, internal resistance increases, and heat generation rises. Insufficient heat dissipation can easily lead to local overheating and thermal runaway.
- Electrolyte leakage: After long-term cycling, battery aging can cause electrolyte leakage, forming a flammable mixture in a confined space that can explode when exposed to sparks.
For example, a 2024 spontaneous combustion incident in a certain vehicle was attributed to electrolyte leakage caused by battery aging.
Mechanical Damage
When the battery pack is collided, squeezed or punctured, it may cause the battery cell to deform, the electrolyte to leak, and form a conductive path, causing a short circuit and thermal runaway.
- Insufficient battery pack structural strength: The battery cells cannot be effectively protected during a collision, or an unreasonable internal layout leads to heat concentration.
For example, in 2021, a certain brand of electric vehicle spontaneously combusted after a side collision. Because the battery pack had no side reinforcement beams, the battery cells were directly squeezed.
External Factors
In addition to problems with the battery itself, some external factors may also cause new energy vehicles to catch fire.
- High temperature environment: In hot weather, battery temperature is more likely to rise, increasing the risk of thermal runaway. Explore more about lithium battery temperature range.
- Overcharging: Faulty or improperly operated charging equipment may cause the battery to overcharge, triggering a runaway chemical reaction within the battery.
- High-voltage wiring issues: Aging, damage, or rat-gnawed insulation on high-voltage cables can lead to leakage or arcing. Poor contact in high-voltage connectors can cause arcing and ignite surrounding combustibles.
- Flammable materials: Using flammable or heat-resistant materials (such as certain sound insulation cotton and wiring harness insulation) increases the risk of fire spread. For example, an investigation into a spontaneous combustion of a certain vehicle model in 2022 revealed that the sound insulation material inside the vehicle failed the flame retardant test, allowing the fire to spread rapidly.
- The insulation layer of the high-voltage wiring harness from the charging port to the battery pack was gnawed by animals.
When Do EV Fires Most Commonly Occur?
According to statistics from more than 270 public cases:
- Over 50% of fires occurred during charging or parking, much higher than collisions (~10%).
- Peak hours: 7–9 a.m. and 1–6 p.m.,when both ambient temperatures and charging activity are typically higher.
- Peak season: Summer, when heat waves and heavy rainfall increase the risk of thermal stress and water-related electrical faults.
- “Spontaneous combustion” cases receive the most attention, as they occur without collision or user operation.
How to Prevent EV Fires Effectively?
Knowing the causes of EV fires is the first step toward prevention. Here are practical safety measures:
Choose Reliable Brands and Models
Choose reputable, technologically advanced brands and models to ensure battery quality and safety. Avoid buying low-priced, low-quality products and avoid selling inferior products as genuine products.
Pay Attention to Battery Technology
Understand the characteristics, advantages and disadvantages of different types of batteries and choose safer battery technologies. For example, new battery technologies such as solid-state batteries and semi-solid-state batteries have higher energy density and are safer.
Practice Safe Charging
- Charge the battery according to the instructions to avoid overcharging, power loss, or long-term fast charging.
- Use the original charger or a charging device that meets the standards.
- Avoid charging in high temperature environments and choose a cool and ventilated place.
- Check your charging equipment regularly to ensure it is working properly.
Conduct Regular Inspections and Maintenance
- Check the battery pack, high-voltage wiring harness, and cooling system every 10,000-20,000 kilometers;
- If the vehicle has been involved in an external collision, it is recommended to go to a 4S shop for a safety inspection to ensure that the battery and other components are intact.
- Pay attention to vehicle software updates and fix BMS vulnerabilities in a timely manner .
Avoid Extreme Conditions
- Avoid long periods of high-speed driving or hill climbing to reduce battery load.
- Avoid parking your vehicle for extended periods in extremely hot or cold conditions.
- Avoid driving through water to prevent the battery from being soaked.
Park Safely and Reduce Heat Exposure
Park in the shade whenever possible. The order of parking locations is:
Underground parking > indoor parking > shaded areas of tall buildings > shaded areas of trees > exposed dirt surfaces > exposed concrete surfaces.
For cars with sunroofs, slightly open them to allow for air circulation and lower the temperature inside.
Strengthen Safety Awareness and Emergency Readiness
- Understand the safety features and emergency measures of new energy vehicles.
- Equip your car with a fire extinguisher and know how to use it correctly.
- If you find smoke, strange smell or other abnormal conditions in your vehicle, you should stop and check immediately and contact a professional in time.
Promote Technological and Regulatory Improvements
- Smart BMS: Uses AI algorithms to monitor battery status in real time and provide early warning of potential failures.
- Aerogel insulation: Fill the battery pack with aerogel material to prevent the spread of thermal runaway.
- Improved regulations: Mandatory battery packs must undergo extreme tests such as puncture, crushing, and fire. Accident tracing mechanisms will be established, requiring automakers to disclose the causes of spontaneous combustion and corrective measures.
What to Do If Your EV Catches Fire?
If a new energy vehicle unfortunately catches fire, you should remain calm and take the following measures:
- Do NOT attempt to extinguish it yourself: Once a new energy vehicle catches fire, the fire will be very fierce, and most car fires occur in the rear battery area, which requires power outage. It is too professional. It is not recommended that people extinguish the fire by themselves, nor is it recommended to control the vehicle according to the traditional fire extinguishing method of fuel vehicles, so as to avoid casualties.
- Stop the vehicle immediately and evacuate quickly: park the vehicle in a safe area, evacuate the vehicle quickly, and stay away from the vehicle.
- Call emergency services: Dial the fire alarm, tell the fire rescue personnel the make and model of the vehicle, as well as the fire situation, and wait for professional personnel to deal with it.
- Do not return to the vehicle: In actual firefighting operations, new energy vehicle batteries are prone to reignition. Even after the fire is extinguished, it is still recommended that car owners do not return to the car to avoid losing more than they gain.
- Avoid inhaling toxic fumes: During the firefighting process, you must prevent inhalation of toxic gases such as hydrogen fluoride and hydrogen cyanide emitted by battery burning.
Conclusion
EV fires are a complex issue involving battery chemistry, electrical safety, heat management, design, and user behavior. By understanding the true causes of EV fires, adopting preventive measures, and mastering emergency response, we can significantly reduce risks and ensure safer travel. With continuous advancements in technology and stronger regulations, EV safety is improving year by year, making electric vehicles a more secure and reliable choice for the future of mobility.
FAQ
Are EVs more likely to catch fire?
No. EVs are actually less likely to catch fire than gasoline cars, but fires can be harder to extinguish.
What causes EV fires most often?
Battery thermal runaway, poor cell quality, charging faults, or crash damage.
How can EV fires be prevented?
Use certified chargers, avoid overcharging, maintain the battery, and keep cooling systems working.
What should I do if my EV catches fire?
Stop, move away, call emergency services, and don’t try to extinguish it yourself.
Do EV fires happen during charging?
Yes, some do — usually from faulty chargers or overheating batteries.
Does fast charging increase the risk of spontaneous combustion?
Frequent fast charging accelerates battery aging, indirectly increasing the risk. During fast charging, high current flows through the battery cells, generating increased heat. If the thermal management system doesn't respond promptly, it could cause localized overheating. Recommendations:
- Use slow charging for daily commuting;
- Occasional fast charging is acceptable for long trips, but avoid charging to 100% and then parking in high temperatures;
- Select a model with intelligent climate control.
Who we are
TYCORUN is a leading company in the battery swap industry, focusing on the research and development and manufacturing of battery swap stations and lithium-ion batteries. We are committed to providing efficient and sustainable energy solutions for electric two-wheeled vehicles such as electric motorcycles, electric tricycles, and electric scooters (explore battery swapping vs charging station).
Willow
Willow is a materials engineer with a Master’s degree in Materials Science and Engineering, specializing in lithium-ion battery materials and energy storage technologies.
Her work focuses on EV battery swapping solutions, battery innovation, and new energy industry trends, aiming to translate research insights into practical applications for sustainable transportation.
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