Battery Safety: Addressing Fire Risks in Light Electric Vehicles
Safety issues – What is happening with LEV fires in the roads?
Lithium-ion (Li-Ion) batteries have become the primary power source for Light Electric Vehicles (LEV) due to their high energy density and extended lifespan. However, they have inherent safety risks. Inadequate design and poor manufacturing quality can intensify these risks, leading to catastrophic consequences such as fires and explosions.
Thermal runaway in lithium-ion batteries is the primary safety concern for LEVs. This occurs when internal reactions within the battery generate heat faster than it can dissipate, leading to a self-sustaining increase in temperature and creating a domino effect. When thermal runaway conditions are not properly considered and mitigated, failure modes include overheating, melting, and ultimately, fire.
Additionally, short circuits within lithium-ion batteries can occur due to manufacturing defects, electrode contamination, or physical damage. These short circuits can trigger a rapid discharge of energy, generating heat and posing a severe safety risk.
And finally, external forces such as drops, impacts, or crushing can cause mechanical damage to lithium-ion batteries. Without proper protection, these incidents may compromise the integrity of the batteries.
Although no comprehensive national or international statistics document the frequency of LEV fires, incidents occur regularly, and with increasing frequency due to the wide availability of inferior products. The Fire Department of New York (FDNY) documented more than 340 fires, 124 injuries, and 17 deaths in the city caused by LEV in 2023. Furthermore, the Consumer Product Safety Commission (CPSC) issued a recall affecting approximately 22,000 LEV in October 2023 due to concerns that their lithium-ion batteries could ignite, explode, or emit sparks.
Safety Standards - How do we ensure LEV safety?
As the adoption of LEVs continues to increase, several safety organizations around the world have introduced protocols and certifications for vehicles and batteries. UL, a prestigious global safety organization, has introduced a series of stringent safety protocols (UL 2271, UL 2272, and UL 2849) explicitly tailored to micromobility and LEVs. These comprehensive safety standards include exhaustive construction reviews and a wide range of tests, including battery performance, electrical systems, mechanical integrity, environmental durability, and, in some instances, operational evaluations[VR1] [RVP2] .
New York City has prioritized safety in LEVs and their battery systems due to the surge in lithium-ion battery-related fires. The City Council recently passed legislation mandating UL certification for these products, with the goal of reducing the frequency and intensity of accident risks and guaranteeing compliance with state-of-the-art safety protocols.
LEV users must steer clear of any LEV or battery lacking UL certification and adhere to the new FDNY guidelines as a preventive measure to mitigate potential hazards to the community.
New York has adopted the following LEV safety standards:
UL 2271 (applies to batteries of light electric vehicles, LEVs, and covers):
+ Electrical safety: the battery pack should not short-circuit, overheat, or catch fire during use.
+ Mechanical safety: the battery pack should withstand mechanical stress, such as impact and vibration, without rupturing or
releasing hazardous materials.
+ Environmental safety: the battery pack should not leak or emit hazardous materials, and withstand humidity, or rash environmental conditions.
UL 2272 (applies to electrical systems of personal e-mobility devices):
+ Electrical safety: the electrical system of the device is tested for electrical shock and fire hazards. This includes testing for potential overheating, short circuits, and overcharging. If the battery meets the UL2271 or UL2580 requirements, it can be exempted from those tests.
+ Mechanical safety: the device is tested for mechanical stress, impact, and vibration. This ensures that the device can withstand everyday use without breaking or malfunctioning. In addition, motors are tested under overload and locked rotor conditions.
+ Environmental safety: the device is tested for resistance to water, dust, and other environmental factors. This ensures that the device can be used safely in different weather conditions.
UL 2849 (applies to electrical systems for e-bikes class 1, 2 and 3):
+ Electrical safety: the electrical system for the e-bike is tested for battery overcharging and short circuits. Motors are put through a locked rotor and overload test.
+ Mechanical safety: the critical components are exposed to vibration, impact, and shock tests to verify if they can withstand mechanical abuse and not cause harm to the user.
+ Environmental safety: the housings are tested for ingress protection and mold stress for polymeric enclosures to ensure safety in different weather conditions.
+ Operation: the motor and bike are tested for reverse pedaling and startup assistance modes.
Why PEM Motion - Who can help you overcome these problems?
PEM Motion stands out as a strong partner, offering comprehensive solutions to mitigate the inherent risks associated with battery technology. With more than ten years of experience in the field of Li-Ion.
PEM's strong expertise in micromobility, Li-Ion cell technology, electronics and software development, functional safety, testing, and regulatory compliance enable us to support you in diverse applications across multiple industries.
We can help you with:
· Battery Design and Safety Concept: PEM Motion employs robust safety concepts to fortify your lithium-ion battery design. Failure Mode and Effect Analysis (FMEA) and thorough Risk Assessments are integral components of our methodology. Through these systematic processes, we identify potential failure modes, assess associated risks, and implement proactive measures to enhance safety.
· Battery Construction Review: We excel in conducting thorough battery design revisions and providing necessary recommendations. We ensure that your battery systems are meticulously designed to handle all safety issues.
· Customized BMS: Our Hardware and Firmware teams are willing to provide tailored solutions for the brain of your battery - the BMS (Battery Management System). Recognizing that each application has unique requirements, we specialize in crafting BMS designs that align with your specific functional, performance, and safety targets.
· Certification Process Support: Navigating through the homologation process can be complex, but with PEM Motion, the journey becomes seamless. We guide you effortlessly through the homologation process, ensuring compliance with regulatory standards. Our experienced team understands the intricacies of European and American regulatory requirements, positioning us as a knowledgeable partner to support you in meeting normative needs.
Conclusion
Addressing safety issues in the context of LEV, particularly concerning Li-Ion batteries, is vital due to the potential risks of overheating, ignition, and explosions. The increasing incidence of fires and related fatalities underscores the urgency for adequate safety measures.
If you are interested in receiving further information, contact us via email, and let’s discuss your application.
Vanesa Rueda, PhD
Team Lead E/E and Sr. Hardware Engineer
Rodolfo Villalobos
Consultant
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