04.4 Risks - EV fire overall

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.

EV FireSafe AFAC Poster Electric Vehicle SOPs How to manage an EV incident (1).png

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

Burnt vehicle should be stored away from structures, other cars. Monitored for reignition.

All*

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.
Flame temperature information courtesy of the NFPA (US)

Next...04.5 What does the research tell us about EV fires + charging?

04.4 Risks with EV battery fire

There are new risks to emergency & secondary responders from EV battery fires

Let's take a closer look at each new hazard & risk...

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

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

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*

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.

Flame temperature information courtesy of the NFPA (US)