How Riders Are Unknowingly Raising the Battery Fire Risks of E-Mobility

By: Sayon Deb

It took the New York City Fire Department only three minutes to arrive at a home in Queens last April, but with the speed and ferocity of a lithium-ion battery fire, they were too late. An e-bike battery that went into thermal runaway had burst into flames, blocking the only exit, and trapping a seven-year-old boy and his 19-year-old sister, costing them their lives. 

FDNY Chief John Hodges said, “If this was not an e-bike fire, we would have been able to put this fire out without incident, but the way that these e-bike fires occur, it’s like an explosion of fire and these occupants had very little chance of escaping.”

The tragic story uncovers some of the troubling dynamics that UL Standards & Engagement is working to protect against. Our latest report, Raising the Risk: How Safety Oversights of E-Mobility Riders Threaten More Lithium-Ion Battery Fires, sheds light on some of the core issues contributing to the sharp uptick in deadly fires: e-mobility’s popularity in densely populated urban areas combined with a staggering awareness gap about lithium-ion battery safety.

Riders are blocking their fire escape routes

Like the tragedy in Queens, our survey found a staggering 49% of e-bike and e-scooter owners who charge at home are blocking their exits and unaware of the power source’s risks, let alone the speed of lithium-ion battery fires. The Fire Safety Research Institute conducted an experiment that showed an e-bike in thermal runaway completely engulfing a room in flames in less than 20 seconds. 

Video courtesy of UL's Fire Safety Research Institute

Standards protect rider access

It is a risk that can — and should — be mitigated. E-bikes and e-scooters that conform to safety standards are designed to protect against thermal runaway, which can lead to fire or even explosion if the batteries are damaged, faulty, or counterfeit. These standards can protect a market that is surging in popularity among consumers due to their convenience and relatively low cost to purchase and operate. 

E-bikes and e-scooters are in high demand with so-called “gig workers” in urban environments who depend on them for making deliveries or other work-related tasks. The study found that 54% of owners purchased their e-bike or e-scooter for work, and most of them used these for deliveries in the past 12 months (72%). The largest group of riders live in urban areas (45%) and are predominantly low (39%) or middle income (32%). 

Low awareness carries additional risk in urban areas

But the popularity of e-mobility devices has outpaced the knowledge about them, evidenced by a large awareness gap among consumers about the potential hazards — or even that lithium-ion batteries power their e-mobility devices. In fact, 53% of e-bike and 54% of e-scooter owners are unaware their device contains a lithium-ion battery. Nearly half (49%) dismiss personal relevance to fire or electric shock risks, and 48% underestimate the threats from damaged or overcharged batteries. 

These consumers are less likely to follow safety measures to prevent a battery fire, which escalates the risk. In cities, proximity can mean risk for neighbors, as the flames spread quickly through multifamily dwellings. In February, 23 residents of a Washington, DC apartment building were left without homes from an e-scooter fire that was charging in a basement unit and spread quickly to the building’s upper floors. Fortunately, in this case, no one was killed, which the fire department said could likely be attributed to working fire alarms. 

Battery replacements validate safety concerns

Nearly half (48%) of e-bike owners reported replacing an old battery for their e-mobility vehicle. Many of these owners did so for safety reasons: the old battery caught fire (11%), was damaged in a crash (16%), was overheating (24%), or swelling or bulging (28%). All of these are critical reasons to replace the battery. E-mobility device owners must understand that overheating and swelling are warning signs that cannot be ignored. 

Education and observation can save a life. Unfortunately, the survey showed reason to be concerned that riders are ignoring some basic safety practices. Nearly six in ten (57%) admitted to neglecting regular checks on battery health and 66% said the forgo routine inspections for signs of wear and tear on their device. 

Designing policies to prevent tragedy

In 2023, a new law took effect in New York City mandating that all e-mobility devices, batteries, and related equipment sold or leased in the city must be certified as meeting applicable safety standards published by UL Standards & Engagement. These standards cover the batteries and electrical systems of these devices to help mitigate hazards that can contribute to a battery catching fire or exploding. The law came about in response to a sharp rise in deadly e-mobility battery fires. 

Other cities — like San Francisco — have enacted, or are considering, legislation and regulations instituting guidelines for safe charging and storing practices to help reduce the risk of battery fires. 

Addressing risk on multiple fronts

There is a clear need to close the safety awareness gap as more of these devices are purchased by consumers. These root issues point to a two-pronged approach to solving the problem: enhancing consumer safety education and expanding adoption of safety standards. 

These tragedies can largely be prevented, and lives can be saved. The problem is evident and the path to solving it is becoming clearer. We will continue to push for greater standards adoption and to work with everyone who has a stake in a safer e-mobility future.

Sayon Deb is director of insights at UL Standards & Engagement and the author of the report, “Raising the Risk: How Safety Oversights of E-Mobility Riders Threaten More Lithium-Ion Battery Fires.”