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Why So Many e-Bike Fires? Soteria's e-Bike Battery Safety Project Has Answers

Soteria's e-bike battery safety initiative minutely examines battery packs and rider behavior: Interim results raise serious concerns about battery pack safety.

Posted by Staff

June 30, 2023

3 Min Read
NYC e-bike.jpg
An electric bicycle stands parked in the streets of Manhattan.Spencer Platt / Staff/Getty Images News

Last year, New York City witnessed more than 200 fires attributed to e-bike batteries, tragically claiming the lives of 6 individuals. As for the current year, the number of fires has surpassed 100, leading to a devastating toll of 13 fatalities.

The ongoing rash of e-bike fires—in New York and elsewhere—has been a topic of great concern in recent months. The Soteria Battery Innovation Group, in collaboration with industry partners including NASA, Clemson University, Amphenol, Polaris, and Munro & Associates, has initiated a project to address the need for more information regarding battery safety in e-bike battery packs.

The preliminary findings of Soteria’s investigation indicate that modern battery safety technology is not effectively utilized in e-bike battery packs. The project employs four strategies to gain insights into the state of the industry:

New E-bike battery pack disassembly: The disassembly of new OEM and third-party e-bike battery packs aims to identify best practices, beneficial design features, design flaws, and missing safety features.

Used e-bike battery pack disassembly: The disassembly of used e-bike battery packs aims to identify potentially dangerous wear conditions and damages.

Rider profiling: E-bike riders were surveyed and interviewed to understand their usage patterns, experiences with fires, and demographic factors that may contribute to fire probability.

E-bike OEM interviews: Interviews were conducted with e-bike Original Equipment Manufacturers (OEMs) to gain insights into the safety design aspects of battery packs.

Preliminary findings highlight battery pack shortcomings

While the project is still in progress, the preliminary findings are the following:

1. Riders' experience with fires: Out of 1,018 surveyed e-bike riders, approximately 15% (157 riders) reported experiencing an e-bike battery fire.

2. Third-party battery pack cost and quality: Third-party battery packs were found to cost around 40% of the OEM equivalents but often possessed lower-quality components and safety features.

3. Factors influencing e-bike fire probability: The probability of experiencing an e-bike fire was increased for riders engaged in delivery services, those performing their own maintenance, users of refurbished batteries, and riders of mountain bikes.

4. Disassembly findings: The disassembly of eight e-bike battery packs revealed several shortcomings, including a lack of cell balancing capability in four battery packs (leading to potential overheating and fires), absence of battery pack venting provisions, inadequate battery protection materials between individual batteries, insufficient spacing between cells to prevent fire propagation, and the presence of potentially unsafe counterfeit cells in two packs. Only one battery pack possessed UL 2271 certification, while two others were certified under UL 2849, which includes battery pack requirements.


Not all bad news

The project also uncovered significant positive results:

1. Fire protection during charging: Many surveyed e-bike riders have implemented fire protection measures during the charging process.

2. Use of OEM battery packs: Approximately 67% of the surveyed riders exclusively utilized OEM battery packs.

3. Exemplary battery pack design: One specific battery pack stood out among the disassembled packs for having the safest design.

4. Temperature sensors: Most disassembled battery packs incorporate some form of temperature sensor.

The project will culminate in a workshop on October 16-17 in Greenville, SC, where the complete findings will be presented to project participants, who will collaborate in developing safety strategies and best practice recommendations for manufacturers and owners. Most strategies are anticipated to be implemented at little to no additional cost.

The issue of e-bike battery safety is a pressing concern that requires immediate attention. The findings from the Soteria Battery Innovation Group's project, in collaboration with industry partners, highlight significant gaps in battery safety technology utilization in e-bike battery packs. Addressing e-bike battery safety concerns is vital to ensure the well-being of riders and prevent tragic incidents.

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