In the past decade, mobile electric devices have proliferated throughout our society, presenting unique fire protection hazard to the built environment. From electric cars to mobility devices, such as e-bikes and scooters, these devices require careful  consideration when stored in or near a building due to their use of lithium-ion batteries in their design. Understanding the risks associated with these batteries and implementing appropriate mitigation strategies is essential for design teams, building owners, and fire protection professionals to protect lives and property.

How Battery Fires Start

Lithium-ion battery failures, caused by mechanical damage, manufacturing defects, or typical wear on the battery, often result in thermal runaway. During thermal runaway, energy stored in the battery is discharged into the surrounding environment, igniting the surrounding environment. 

Batteries failures often produce off-gassing, which is the release of hydrogen gas due to the previously mentioned thermal runaway. Once the hydrogen gas reaches a sufficient concentration and reaches the required temperature, the gas combusts, which can create deflagration. Additionally, the plastic that encases the battery often ignites, further fueling the fire.  

Code Mandates for Electric Battery Storage

Code cycles occur once every three years, so codes such as International Fire/Building Codes, NFPA 1: Fire Code, NFPA 101: Life Safety Code, and NFPA 5000: Building Construction and Safety Code lag behind emerging technologies, like mobile battery-powered devices. While some jurisdictions have adopted local ordinances to address the risks associated with battery storage, there are currently no universally mandated requirements. However, fire protection experts are in the process of researching and developing recommendations for energy storage systems that will eventually become code.  

Despite the absence of specific codes or standards, design teams and building owners are still responsible for addressing these new hazards. For new buildings, the design team is responsible for providing a safe environment for occupants and emergency responders. New hazards necessitate reevaluating a building’s existing fire and life safety systems, so owners must collaborate with fire protection experts to assess their systems and identify mitigation strategies. For example, e-bike users may store their bikes in a rack that typically stores regular bikes near a commercial building, which poses a new fire hazard to the facility that the building owner needs to address and mitigate.  

Types of Mobile Batteries and Their Hazards

Batteries come in many shapes and sizes. Stationary batteries, or battery energy storage systems (BESS), are covered by code in Section 1207 of the International Fire Code and are not the focus of this article.  

Mobile batteries provide power to electric cars, boats, bikes, scooters, skateboards, leaf and snow blowers, and tractors, among others. The following sections cover each of these devices and their storage risks.  

Electric Car and Electric Boat Batteries

Electric vehicle and boat batteries are one of the physically largest and most hazardous to a structure due to the amount of energy they store. However, these systems are limited by where cars and boats can physically go, and they are more regulated than other types of mobile batteries. Additionally, these e-vehicles require users to have training and licensing to operate them. These licenses have some safety built into them in that users will park their cars in a designated area, whereas an unlicensed e-bike user, for example, may leave their bike anywhere, increasing the risk of a fire. 

Electric Car Best Practices

Electric cars are the most ubiquitous electric mobility devices of all types. However, there are well-developed design criteria requirements for EVs.  

The design team and/or facility owner should consider the following best practices for electric car storage.   

• Clump charging stations together.
• Separate EVs from other cars.
• Designate the electric car area in open areas that firefighters can easily access, such as the first floor of a parking garage.
• Increase fire sprinkler density for charging areas.

For example, the city of San Francisco provided a local requirement to increase the fire sprinkler density for electric car charging locations by double what NFPA 13 states for typical parking areas. Providing more water is a way to control the fire spread to other items, though it will not extinguish the battery fire specifically, as lithium-ion fires can burn without oxygen. The increased water demand is generally not an issue if a facility already has other high-water use elements, such as car stackers, automatic standpipes, BESS systems, etc. 

Electric Boat Best Practices

Electric boats present similar challenges to structures as electric cars. Similarly to electric car charging stations, electric boat charging/storage locations should be:  

• Separated from other boats and combustible building elements
• Not enclosed
• Located in areas accessible to firefighters

Electric Personal Mobility Device Batteries (E-Bikes, Scooters, and Skateboards)

Mobility devices have gained significant popularity in recent years. While the batteries within electric bikes, scooters, and skateboards are smaller than those of EVs, they are less regulated, and operators often leave these devices in unpredictable locations. The unpredictability of these batteries’ use and location presents unique hazards to public spaces and the built environment. 

Some hazards that these devices present include: 

• This higher variance in the location of potential ignition creates challenges for a building’s fire and life safety systems. 
• Devices left near the entrance of a building present a significant hazard to the exterior of the building and reduce exit capacity for occupants. 
• Younger individuals often use electric bikes and scooters and do not require a license, further increasing unpredictability. 
• The batteries within these devices are more at risk for mechanical damage.

Electric Personal Mobility Device Best Practices

Given these risks, best practices for building owners that have these devices stored on their property include:  

• Prohibiting e-bikes, scooters, and skateboards inside buildings that do not have the proper fire suppression systems
• Moving bike racks and other storage elements to a sufficient distance from the exits
• Removing building elements that make bike or scooter locking convenient for users
• Training security personnel to enforce rules that prohibit electric bike and scooter entrance/parking
• Training building occupants on identifying a battery in the early stages of combustion and what to do
• Designating specific areas of a building for e-bike and scooter storage that have fire protection features, such as increased sprinkler density or gas detection systems similar to those found for stationary battery systems

Other Electric Powered Mobile Items (leaf and snow blowers, tractors)

Other types of mobile battery-powered items include electric sit-on-top mowers, leaf blowers, and snow blowers, which are often stored inside a retail store or in a residential tool area. The size of these batteries varies more than the devices listed above. 

Storing these items inside a retail facility may increase the building’s exposure to the abovementioned hazards, as the existing fire protection systems most likely do not protect against battery fires. The store owner should work with a fire protection engineer who can re-design the existing systems for that commodity. If customers can try out the devices within the facility, building owners must take extra precautions to avoid mechanical damage to the device batteries. 

For residential properties, stationary battery systems code limits residents to a specific quantity of devices. However, because of the mobile nature of these devices, those code sections may not adequately address the risk. Storing these battery devices separately in one’s house might be the best way to mitigate the fire risk associated with them. 

Battery Risk Mitigation Services

With new technology comes new risks, and all stakeholders in the built environment must proactively address the challenges posed by mobile battery-powered devices. Telgian Engineering & Consulting (TEC) specializes in mitigating fire risks associated with both mobile and stationary battery systems. TEC is actively involved in the National Fire Protection Association (NFPA) code development committees, giving us insight into new best practices for mitigating battery risk. 

Our battery-related fire protection services include:  

• Fire Protection Master Planning
• Battery Code Consulting for Clients, Architects, and Engineering Teams
• Site Surveys and Hazard Analyses
• Fire Testing
• Performance-Based Design
• Fire Suppression Design and Engineering

If you have questions regarding battery risks for your new or existing facility, please contact TEC to discuss how we can collaborate and mitigate any fire hazards associated with these various devices. 

About the Author

Eric Roux, PE, is a fire protection engineer at Telgian Engineering & Consulting with over 7 years of experience in the industry. Mr. Roux engages in various projects that include sprinkler design criteria, fire alarm design criteria, fire smoke modeling, smoke control, and code consulting. Mr. Roux is particularly interested in battery energy storage systems and how to address the hazards these systems present. If you have any questions about the article, please reach out to Eric at eroux@telgian.com. 

Contact TEC today to learn more about our fire protection, life safety and security services.

Media and Interview Inquiries: Please contact info@telgian.com