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04.4 Risks with EV battery fire
There are new risks to emergency & secondary responders from EV battery fires
While there are many similarities to ICEV fires, electric vehicle battery fires pose a range of new challenges to emergency responders & everyone handling EVs post-incident, including tow, repair, storage, salvage & wrecking.
EV FireSafe presented this poster at the Australiasian Fire Agencies Council conference in 2023, which succinctly outlines risks of both battery fire & road traffic collision. The poster can be downloaded below for the use of emergency agencies.
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Let's take a closer look at each new hazard & risk...
To highlight the mix of old & new risks, we have compared EV traction batteries against traditionally fuelled vehicle fires, to best highlight how risks are the same, & where they differ.
Risks listed are based on research & discussions with Australian & international subject matter experts. We are not offering fireground management or suppression recommendations, only sharing information & best practice methods.
Internal combustion vehicle fire
Electric vehicle traction battery fire
Vehicle immobilisation
As EVs don't emit engine noise, immobilising an identified EV is a priority to ensure there is no risk to on scene personnel from unexpected movement on accerator pedal
Listen for engine, switch off. Apply park brake. Chock wheels.
No engine noise, find proximity key & remove. Apply park brake. Chock wheels.
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.
Toxic gases from burnt fuel & metal, plastics
Toxic gases from burnt lithium ion cells*, metal, plastics
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.
Possible deflagration from fuel
Possible vapour cloud explosion
Flame intensity
As flammable gases are vented from battery cells, they may create 'jet like' flames.
Intense flames, easing in a short time
Jet like, highly directional flames, intense burn for extended period
Flame temperature
NFPA testing (August 2023) found EVs & ICEVs burn at a similar heat, refuting the common misconception that EVs burn hotter than ICEV.
Flames at 815-1000 degrees celcius
Similar flame temperatures
Debris projectiles
All vehicle fires produce projectiles, however the venting of gases from lithium-ion battery cells may cause additional debris
Chance of debris release
Battery cell debris projectiles likely as they enter thermal runaway
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. See 04.9 Suppression methods for more.
Application of water or foam to suppress flames
Water application to suppress flames + cool battery pack.
Water supply
A greater volume of water is typically required to suppress a traction battery fire, compared to an internal combustion vehicle.
Up to 4000L (one tanker) of water used
At least 4000L. Some EV fires have used up to 100,000L, with ~10,000L used on average. Establish hydrant &/or additional tankers
Suppression + cooling can take hours
Several hours may be needed to knock down flames & cool the traction battery.
Fast knock down of flames with water or foam
Longer knock down due to thermal runaway in battery pack
More resources may be required
For the reasons outlined above, more firefighters & appliances than usual may be needed.
Eg. One breathing apparatus operator
Eg. Breathing apparatus operators x 2 due to longer suppression time
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.
Very low risk of electrocution from 12V battery
Potential risk of electrocution from high voltage battery, cables & components
Electrocution risk from DC HV - extrication
Our research found little to no risk of electrocution from EV HV during extrication of occupants, & 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.
No risk
Potential risk of electrocution from high voltage battery, cables & components.
Electrocution risk from DC HV - submersion
Our research found little to no risk of electrocution from EV HV while submerged, & 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.
No risk
Potential risk of electrocution from high voltage battery, cables & components.
Electrocution risk from DC HV - stranded energy
Following fire, a partially intact traction battery or loose, scattered battery cells pose a risk of electrocution from the stranded energy. There is no way to measure or remove stranded energy. Wear appropriate PPE & treat as energised.
No risk
Potential risk of electrocution from high voltage battery, cables & components.
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.
Once suppressed, low risk of flame reignition
Once suppressed, monitor for reignition > 60 mins. Listen for hissing or popping noises, dark vapour cloud.
Toxic particulate matter
The toxicity of a lithium-ion battery fire poses a risk of poor air quality & water run off contamination. Enclosed spaces may need heavy duty cleaning, however t
Once vehicle is removed, wash area to remove debris
Monitor water run off & air quality.
Secondary ignition while tow loading & transporting
Wheel turn while transporting an EV with a partially burned traction battery may engage regenerative braking, supply power to battery & cause reignition. Tow drivers should access the correct emergency response guide and tow on flatbed only where possible.
Remove burnt vehicle
Monitor for reignition during removal & transport
Secondary ignition in storage
Severely damaged EVs should be monitor for heat, vapour & flames for an extended period, as per EV FireSafe's EV ABC.
Store & wreck vehicle
15m
15m
Burnt vehicle should be stored away from structures, other cars. Monitored for reignition.
All*
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Lithium ion battery cells expel hydrogen, carbon monoxide, carbon dioxide, hydrogen fluoride, hydrogen chloride, hydrogen cyanide, organic solvents, ethane, methane, hydrocarbons, sulphur dioxide, nitrogen oxides, among others. Source: Prof Paul Christensen, University of Newcastle.
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Flame temperature information courtesy of the NFPA (US)
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