Lithium-ion (Li-ion) batteries in electric vehicles (EVs) pose distinct risks to first responders after a collision. Specifically, high energy density and thermal runaway can spark intense fires that are difficult to suppress.
This article discusses the inherent dangers associated with damaged Li-ion batteries, outlines first responder procedures, and reviews key industry safety standards. It also explores how EV isolation mechanisms, thermal management systems, and high voltage disconnects can help reduce risks to emergency personnel.
Understanding first responder risks
Accessing high-voltage disconnects following an EV collision is challenging for first responders. Crucial for deactivating the vehicle’s power system, these disconnects are often unreachable due to extensive structural damage. When properly engaged, they mitigate electrocution risk by de-energizing and isolating electrical systems.
EV Li-ion batteries are also susceptible to thermal runaway, a self-sustaining exothermic reaction triggered by internal short circuits or external damage. This can lead to rapid overheating, damaging multiple battery cells, or causing intense fires. Moreover, the compact and sealed design of battery traction packs limits direct access to cells and reduces the effectiveness of traditional firefighting methods.
As a result, emergency crews often spend hours spraying large volumes of water over the vehicle, particularly targeting the battery area, to effectively manage and extinguish fires.
Damaged Li-ion batteries frequently retain stranded energy, posing significant hazards to first responders. This includes an increased risk of electrocution and spontaneous reignition of fires, particularly when handling high-voltage components during rescue operations. Notably, this stranded energy can remain dangerous even after an initial fire is extinguished, requiring continuous monitoring during post-incident handling and vehicle removal.
Responding to an EV accident or incident
When responding to EV collisions, emergency crews rely on targeted strategies that differ significantly from those used during incidents involving vehicles with internal combustion engines (ICE). The EV model is identified, allowing the emergency crew to analyze the battery layout and gauge potential hazards.
Next, the EV is immobilized and stabilized, while the 12-volt system is disconnected to minimize electrical risks. All high-voltage components are nevertheless treated with extreme caution, particularly when thermal runaway or stranded energy is suspected. Various fire suppression methods are deployed if necessary, including spraying large volumes of water over the EV battery area.
When considered safe for transport, the EV is towed to an automotive shop for inspection and assessment. Specialized technicians perform repairs and battery replacements under stringent safety measures, effectively neutralizing risks like lingering high voltage. A comprehensive evaluation and repair process also includes detailed examinations of the EV’s electrical systems and diagnostics to ensure the complete restoration of safety features and functionality. This approach addresses immediate risks, including lingering high voltage, long-term safety, and reliability.
Exploring emergency response guides and standards
Emergency response guides (ERGs), especially those that adhere to ISO 17840 standards, provide crucial safety information for first responders. These comprehensive guides standardize vehicle model and battery type identification through clear labeling and color coding, enabling first responders to rapidly assess fire, electrocution, and thermal runaway risks. They also provide detailed information about the location and specifications of high-voltage components, battery systems, and energy storage mechanisms.
Additional standards play a significant role in shaping ERGs. For example, US Federal Motor Vehicle Safety Standard (FMVSS) 305 focuses on protecting vehicle occupants and first responders from electric shock and securing the integrity of high-voltage sources during and after crashes. Similarly, Global Technical Regulation (GTR) 20 outlines recommendations for battery protection, electrical isolation, and impact resistance.
Lastly, the Society of Automotive Engineers (SAE) J2990 standard offers emergency procedures and post-crash safety guidelines.
Navigating safety-first EV design considerations
Adopting EV designs prioritizing safety with essential components and systems is a top priority for automotive engineers. These include:
- Emergency disconnects: Helps first responders and technicians quickly and safely disconnect batteries from the vehicle’s electrical system.
- Isolation mechanisms: Designed to automatically disconnect high-voltage power in the event of a crash, these mechanisms significantly reduce the risk of electric shock.
- Thermal management: Maintaining battery temperature within safe limits, thermal management systems prevent overheating and contribute to fire prevention.
- Impact-resistant battery placement: Strategic installation of battery packs, typically in locations that minimize collision impact risks, further bolsters safety.
- Battery structural integrity: Durable and fire-resistant housing protects battery cells from physical damage in accidents, minimizing the likelihood of fire and thermal runaway.
- Water mist and spray: Designed to cool and suppress fires, these evolving systems would mitigate thermal runaway to reduce the risk of reignitions.
- Internal fire suppression: An emerging technology, these systems would be embedded in EV battery packs and activated during thermal events.
Li-ion battery traction packs pose clear risks to first responders in the aftermath of EV collisions. Specifically, high energy density and thermal runaway can spark intense fires that are challenging to suppress. When responding to EV collisions, emergency crews rely on ERGs, particularly those adhering to ISO 17840, FMVSS 305, and SAE J2990 standards.
These guides assist first responders in safely managing the vehicle’s electrical systems, including high-voltage components, and provide strategies for minimizing electrical risks.
- Handling Lithium-Ion Batteries in Electric Vehicles: Preventing and Recovering from Hazardous Events, Springer Link
- Fire Safety of Batteries and Electric Vehicles, FSRI
- Safety Risks to Emergency Responders from Lithium-Ion Battery Fires in Electric Vehicles, NTSB
- Electrical Vehicle Fires: A Few Tips for First Responders and Firefighters, OnlineSafetyTrainer
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Filed Under: Batteries, FAQ