EV Fire Safe
EV Battery Fire Knowledge
Most people don't know the EV Battery Fire Know-how
Every fire involving the traction batteries of electric vehicles originates from a phenomenon known as thermal runaway. This process begins when a short circuit occurs within a battery cell, leading to uncontrolled heating. Lithium-ion batteries, known for storing a significant amount of energy within a compact area, are designed to efficiently transform chemical energy into electrical energy during regular use.
- Thermal Runaway: This is a condition where an increase in temperature changes the conditions in a way that causes a further increase in temperature, often leading to a self-sustaining reaction. In the context of EV batteries, which are typically lithium-ion, thermal runaway can occur if the battery is overheated, overcharged, or physically damaged, leading to a rapid and uncontrolled increase in temperature.
Overcharging: Charging the battery beyond its designed voltage limit can cause excessive heat generation and potentially lead to a fire.
Electrical Short Circuits: A short circuit within the battery cell or pack can generate excessive heat, potentially leading to a fire if the battery’s thermal management system fails to dissipate the heat quickly enough.
Physical Damage: Accidents or physical impacts can damage the battery’s structure, leading to internal short circuits or breaches of the cells, which can result in fires.
While there are many similarities to ICEV fires, electric vehicle battery fires pose a range of new challenges to emergency responders.
Exposure to toxic gas
Traction battery fires emit a mix of highly flammable toxic gases, including hydrogen fluoride & hydrogen chloride. Breathing apparatus should be worn.
Risk of explosion
As battery cells enter thermal runaway & emit a cloud of flammable gases (vapour), there is a risk of it exploding without warning.
Flame intensity
As flammable gases are vented from battery cells, they may create ‘jet like’ flames.
Flame temperature
NFPA testing (August 2023) found EVs & ICEVs burn at a similar heat, refuting the common misconception that EVs burn hotter than ICEV.
Debris projectiles
All vehicle fires produce projectiles, however the venting of gases from lithium-ion battery cells may cause additional debris
Fire suppression
Methods established for ICEV fires cannot adequately control thermal runaway as it is a self-generating, unstable chemical process that produces it’s own oxygen & hydrogen.
Water can be used to cool the battery, it can be allowed to burn out, or the entire pack or vehicle can be submerged in water.
Electrocution risk from direct current high voltage (DC HV) – suppression
Our research found little to no risk of electrocution from EV HV when using unbroken stream of water, & no cases or near misses for responders globally. However, it is advisable to always treat EV as if it is energised, wear appropriate PPE, DO NOT contact orange HV with hose or body.
Secondary ignition on scene
There is a moderate risk of an EV battery fire reigniting following initial suppression, with some EV reigniting hours, days or weeks later. Post-incident, crews should conduct EV FireSafe’s EV ABC method & the EV should be monitored using a TIC. Tow truck drivesr should be appraised of the situation & the emergency response guide found.
A third of reported electric vehicle traction battery fires occured while connected to energised AC or DC charging, or within one hour of being disconnected from energised charging.
Suppression, isolate the EV on fire with oxygen or about to catch fire with fire blankets. Using a high-temperature resistance fire blanket that is placed over an EV to contain flame. If used in time, blanket will contain flames and stop fire spread to make further damage to nearby vehicles and assets.
