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A fire ripped through a Kensington rowhome early Sunday morning, killing a young girl and her mother in one of the latest deadly Philadelphia blazes linked to a lithium-ion battery.
Firefighters responded to the 3300 block of D Street around 3:30 a.m. Oct. 11. Investigators determined that a battery from an electric bike in an upstairs bedroom sparked the fire. Two residents escaped through a second-story window, while firefighters rescued the mother and daughter from a back bedroom. The 3-year-old girl died Sunday, and her 22-year-old mother died days later from her injuries. Officials said the home had no working smoke alarms.
The tragedy is part of a growing fire safety problem in Philadelphia. The fire department responds to an average of nearly one lithium-ion battery event per week, according to an Oct. 13 article co-written by Philadelphia Fire Battalion Chief Kevin Donahue and UL Standards & Engagement CEO Jeff Marootian. Not all those events necessarily become fires, but officials say the increasing use of rechargeable batteries presents new challenges.
Lithium-ion batteries power everything from phones and laptops to e-bikes, scooters and electric cars. Most likely, you’re reading this on something powered by a lithium-ion battery. Most function safely, but when they fail, the results can be devastating.
Billy Penn spoke with Adam Barowy, who directs battery fire research at the Fire Safety Research Institute (FSRI), where he studies how lithium-ion batteries ignite, how quickly those fires spread and how firefighters can respond. Philadelphia Fire Department Executive Chief Dan McCarty also offered advice on the risks and how to avoid them.
Why do lithium-ion batteries catch fire?
Lithium-ion batteries have become popular because they’re relatively affordable, rechargeable and capable of storing enormous amounts of energy in a small space. Barowy described the technology as revolutionary, allowing manufacturers to replace traditional power cords with portable batteries.
“If something had a power cord at some point in our lives, it probably will have a battery because the batteries make things more convenient to use,” Barowy said.
But storing so much energy comes with risks. When a battery is damaged, overheated or overcharged, it can experience a phenomenon called thermal runaway, in which chemical reactions inside the battery produce heat that triggers additional reactions. The resulting buildup can release flammable gases and ignite the battery.
Even well-manufactured batteries can experience thermal runaway under sufficiently severe conditions, but lower-quality materials, improper charging and damaged components make failure more likely.
How dangerous are lithium-ion battery fires?
The biggest danger is their speed.
In experiments recreating residential e-bike fires, FSRI researchers found that flames could spread rapidly enough to ignite nearby furniture and building materials, leaving occupants almost no opportunity to escape.
“In our experiments, we saw as little as a minute is available for escaping a residence,” Barowy said.
On June 19, a charging e-bike battery sparked a fire on the 2600 block of South Mildred Street. The fire department has since confirmed two deaths in the incident. The home had working smoke alarms, but the fire spread so quickly that residents became aware of the flames before the alarms could warn them.
In New York City, where the growing number of delivery workers using e-bikes helped make battery fires an especially significant problem, the fire department recorded 268 lithium-ion battery fires in 2023, killing 18 people. The following year, that number increased to 277 fires, although fatalities fell to six.
How should you charge and store your batteries?
“We recommend people don’t charge overnight and don’t charge unattended,” Barowy said.
He recommends using only chargers provided or approved by the manufacturer, unplugging devices once fully charged and avoiding cheaper aftermarket batteries that may not have the same protective circuitry.
McCarty advises residents to charge larger devices outside whenever possible.
“Right now, honestly, I’m not comfortable recommending charging them at all in the house, and I’m someone who owns three electric scooters,” he said.
For Philadelphians living in rowhomes or apartments, where outdoor charging isn’t always realistic, both experts emphasized keeping batteries away from exits and combustible materials. Charging an e-bike in a narrow hallway or near a front door can turn an ordinary escape route into a deadly obstacle.
How can you tell if a battery is safe?
Cheaper, uncertified lithium-ion batteries can carry a greater risk of catching fire, particularly when lower manufacturing standards and inadequate safety protections make them more vulnerable to overheating or overcharging.
Consumers should look for third-party safety certification when purchasing devices. Barowy identified UL 2849, which covers e-bike electrical systems, and UL 2272, which applies to personal electric mobility devices, as important safety standards. Batteries may also be certified under UL 2271.
Barowy said there’s no reliable figure for how many lithium-ion devices on the market meet those standards, but uncertified products are a particular concern.
Once a device is purchased, individuals should watch for unusual heating, swelling, discoloration or strange odors. Hissing, popping and smoke are especially urgent warning signs. A battery showing those symptoms should no longer be used, and residents should move away immediately if failure appears imminent.
What should you do if a battery catches fire?
Immediately get out and call 911.
Both experts strongly advised against attempting to extinguish a large lithium-ion battery fire yourself. McCarty said the combination of intense heat, fast-moving flames and smoke can overwhelm even someone familiar with fire safety.
McCarty urged residents to maintain working smoke alarms and develop a fire escape plan with multiple possible exits. If a fire blocks the front door, residents should already know where else they can go.
What about batteries you no longer need?
The danger doesn’t necessarily disappear when a battery stops working. McCarty recalled a major fire at a Northeast Philadelphia waste facility that he said began with a small lithium-ion battery and required more than 20 fire apparatus to respond.
Philadelphia residents should never throw these batteries into household trash or curbside recycling. Instead, the city accepts lithium and rechargeable batteries at its six sanitation convenience centers. Residents can also bring them to designated household hazardous waste collection events, including one scheduled for Nov. 7 in Port Richmond.
For McCarty, battery safety ultimately comes down to planning ahead, whether you’re charging a scooter, buying a replacement battery or figuring out how to escape your home.
“Where do I keep this? Where do I store this? If this did combust, does this trap me in the house?” he said.
“These devices in your house, they put you at risk. Period.”
Are lithium-ion batteries a new fire safety threat?
Not entirely. Lithium-ion batteries have been used in consumer electronics for decades, but their growing presence in larger devices like e-bikes and scooters has created new challenges for fire departments.
McCarty compared their rise to past changes in building construction that forced firefighters and lawmakers to rethink fire safety. He specifically pointed to Philadelphia’s 1991 One Meridian Plaza fire, which killed three firefighters and helped prompt changes to high-rise safety requirements.
“Most times in situations, tragedy leads to that change in the fire service where we see this emerging trend or this area of opportunity that we, as the fire service, need to get ahead of,” McCarty said.
He sees lithium-ion batteries as another emerging hazard that requires changes in public education, firefighting tactics and potentially regulation.
New York City has already taken that approach. In 2023, lawmakers approved legislation requiring e-bikes, e-scooters and their batteries sold in the city to meet recognized safety certification standards. The fire department also increased inspections of e-bike shops, conducted public education campaigns and targeted unsafe charging practices.
The number of lithium-ion battery fire deaths in New York fell from 18 in 2023 to one in 2025, according to the FDNY. Although that progress cannot be attributed to a single policy, Barowy said requiring certification has helped reduce fire risks.
McCarty said Philadelphia officials are discussing additional safeguards with city regulators.
