Lithium-ion batteries in electric bikes, scooters, and the fire risks they pose

After a string of e-bike fires including one last week in Manhattan's Chinatown that killed four people, New York City and state officials warned that some batteries that power the devices could start electrical fires.

Electronic bikes and scooters used by delivery workers and commuters are on New York City streets and have been officially allowed on Long Island Rail Road trains since spring.

The city passed a package of battery safety laws this spring, and after the Chinatown fire, officials said they would expedite investigations into complaints about batteries at city bike shops and start a safety campaign for shop owners. Last year Nassau County’s chief fire marshal, in a bulletin to all fire departments in the county, warned that the type of battery that powers many of the devices constitutes an “emerging hazard for the fire service.” 

Here are answers to some key questions about the safety of these batteries.

Lithium-ion batteries: What’s the risk? 

Many mobility devices use a rechargeable lithium-ion battery that contains a flammable electrolyte solution allowing electrical current to flow. This battery normally generates a small amount of heat, but under certain conditions — a short-circuit, overcharge, or very high or low ambient temperatures — it can enter a state called thermal runaway, when it generates more heat than can be dissipated.

That can result in very high temperatures, fire, smoke — and even explosions, according to UL Research Institutes, a safety science organization. “When fires occur, they also tend to burn very hot and can be difficult for firefighters to extinguish,” according to the National Fire Protection Agency. 

Phones, laptops and some power tools, appliances and toys use similar battery technology but on a smaller scale and without the same risk, said Nick Petrakis, an engineer with Energy Safety Response Group, an energy storage system consulting firm who helped design New York City’s fire code for mobility devices and energy storage systems.

Mobility device batteries typically link many cells, creating the risk of a chain reaction if runaway occurs in one of them, he said.

How common are lithium battery fires?

This year in New York City there have been 110 lithium-ion fires resulting in at least 13 deaths and 71 injuries, according to the mayor’s office.  

After the most recent string of city fires, Sens. Chuck Schumer and Kirsten Gillibrand (D-NY) announced a $25 million federal grant to fund safer charging stations in city public housing. 

Supporters say the devices are convenient and environmentally friendly, but in a Sunday news conference Schumer warned that "poorly made" batteries can "explode and cause fires." Most battery fires — more than 100 this year in New York City alone — are caused by cheap Chinese imports, he said.

Since last year in Nassau County, there have been seven lithium-ion fires resulting in at least one death and seven injuries, according to Chief Fire Marshal Michael Uttaro. 

Suffolk County authorities did not comment. County spokeswoman Marykate Guilfolyle said earlier this year there had been an uptick in e-bike fires.

Mobility devices are growing more popular. According to data cited by the National Transportation Safety Board, the market is predicted to be $200 to $300 billion by 2030.

What's the potential danger on Long Island? 

“It’s more significant in New York City because of population density and the prevalence of food vendors,” but the devices are also popular in Long Island communities like Long Beach, where a resident might keep an e-bike to go to the beach or get around town, Uttaro said.

Saltwater, a fact of island life, can cause batteries to short circuit and was the cause of a fire last year in Freeport. “Fire codes have not kept up with the technology,” Uttaro said, but county legislators are weighing new rules for safe storage, he said. Christopher Boyle, a Nassau County spokesman, and Guilfoyle did not answer questions about county fire codes covering the batteries. 

In April, the Metropolitan Transportation Authority, MTA began allowing some bikes and scooters on LIRR trains, though onboard charging is not permitted. Rail union officials and others had pushed for tighter restrictions, including permitting for the devices. No fires have been reported from electric bikes or scooters on trains, an LIRR spokeswoman wrote in an email.

Similar technology is used in Long Island's 40,000 electric cars and two large-scale battery energy storage systems.

In February in East Marion, two people died in a Tesla that burned after a head-on collision. Non-crash fires are rare for electric vehicles, but the likelihood increases as they age, according to Joe Young, a spokesperson at the Insurance Institute for Highway Safety.

In late May, a battery energy storage system burned in East Hampton. A spokesman for NextEra Energy, the company that manages the facility, wrote in an email that its fire suppression systems operated as designed and the fire was "quickly contained." 

The facilities are managed to keep equipment running smoothly, and batteries in storage facilities are installed and arranged differently from small-scale consumer products, he said.

Can lithium ion batteries be used, stored safely? 

Yes, said Lorraine Carli, a spokesperson for the National Fire Protection Association. Only use devices, batteries and chargers that are listed with a nationally recognized testing lab and only use the battery and charger that come with your device.

Only charge one device at a time, and never store your device near combustible material or in a hallway or near an exit, she said: “If there is a fire, you’ve blocked the way for you to escape.”

With Mark Harrington