As the nation transitions to electric transportation, fires have shadowed new technology — from the scrappiest e-bikes to the fanciest Teslas.
Fires are an additional challenge for the electro-mobility industry, which already faces cost concerns and infrastructure issues. Not only are these high-profile blazes claiming lives, they risk turning electric progress to ash.
In April 2022, a Tesla vehicle ignited after hitting a tree in New Hampshire and later rekindled in a tow lot. In August 2022, BMW recalled certain BMW i4 and BMW iX vehicles because of fire risk from batteries.
Lithium ion batteries in an e-bike repair shop near New York’s Chinatown caught fire in June, and four people living above the shop were killed. That’s just a handful of the 13 deaths from lithium ion battery fires in the city so far this year — more than twice last year’s total, according to the fire department.
Automakers including General Motors, Ford Motor Co. and Hyundai Motor have spent millions on recalls related to EV fires.
To be sure, EVs are less likely than combustion-engine vehicles to catch fire, but in an area of emerging technology, the bad press has been hard to overcome. Moreover, e-bikes, the source of many deaths, are under far less scrutiny and regulation than autos.
“Unfortunately, the publicity associated with the New York situation is giving the whole industry a black eye,” said Mike Fritz, chief technology officer of Human Powered Solutions. He has been working with e-bikes since the late 1990s.
The bedrock of any modern electric vehicle is the lithium ion battery, which uses the movement of lithium ions across the battery system to charge and discharge the battery.
This process naturally creates a small amount of heat, but damaged or defective batteries can result in an uncontrolled and self-sustaining increase of temperature. This is called thermal runaway.
Thermal runaway can cause violent cell venting that spouts toxic gas or shrapnel from the battery — and fires that are very difficult to control.
“You go from no fire at all to a fully involved fire within seconds,” said Daniel Flynn, chief fire marshal at the Fire Department of New York. “This isn’t something that we’ve really seen for accidental fires in the past. These behave almost like an incendiary fire, like arson, like a gas pour, with the speed that they travel.”
Battery damage can occur during a crash or during an immersion in water, as was the case with lithium ion battery fires during hurricanes Ian and Sandy. Many of the New York e-bike fires involved cheaply constructed batteries, with some manufacturers cutting corners on a key battery part that maintains control in the system — the separator between the anode and the cathode.
The separator is a semi-permeable membrane that keeps electrodes apart but allows the movement of lithium ions across the system. Many are made with polymer films, which are expensive and difficult to make. While one separator material, polyolefin polymer, is only $1.30 per kilogram as a raw material, the processed product costs between $120 and $240 per kilogram.
If the separator fails, it allows energy to dissipate in an uncontrolled fashion, which causes the electrolyte fluid in the battery to heat and ultimately boil. That boiling over-pressurizes the battery and potentially causes the fire.
“These also pose a tremendous risk for rekindle,” Flynn said.
In New York, e-bikes have a huge customer base in delivery drivers with extremely thin profit margins and long days. Inexpensive e-bikes manufactured in China and shipped overseas, and even ones stitched together in New York from secondhand parts, shuttle riders across bridges, sidewalks and cobblestones in the punishing heat of summer and frigid winter storms.
Edward Benjamin, co-founder of the Light Electric Vehicle Association, said the average price of an electric bike in the U.S. is $1,800.
But “you can find electric bikes for 600, 650 bucks,” he said. “To my mind, that’s amazing. I wouldn’t buy one.”
Importers bringing in those inexpensive bikes take advantage of the de minimis level, a customs rule that allows companies to avoid duties on imports below $800.
Bike riders often purchase additional batteries, sometimes mismatched or refurbished, so they can swap depleted cells out and keep moving. They come home from long days zooming down Atlantic Avenue and plug in their beat-up batteries at points of egress and even in bedrooms.
Fly-by-night businesses recharge batteries in plywood cubbies for a fee, extension cords and power strips dripping down the walls like vines. When a fire starts, the results are deadly.
“It doesn’t get any more dangerous than that,” said Fritz. “You may as well lob a hand grenade into the damn place.”
Micromobility products such as e-bikes are regulated by the Consumer Product Safety Commission, which also governs standards for bicycles. Statutorily, the commission can only urge compliance with voluntary standards — unless the current standard does not adequately reduce consumer risk, or unless manufacturers are unlikely to comply. In that case, the commission can issue mandates.
Automobiles and parts, including aftermarket parts, are regulated by two agencies. NHTSA sets standards for vehicle safety, and the EPA sets standards for vehicle emissions. Regulations govern the volume of the horn, the tint of the windows, the ground clearance of the headlights and other features.
NHTSA has overseen recalls associated with vehicle battery issues. It is governing a battery safety initiative aimed at analyzing battery health and cybersecurity, and developing test procedures
Meanwhile, micromobility manufacturers are governed only by voluntary standards for one of their central components, lithium ion batteries. In December, the commission wrote a letter to more than 2,000 manufacturers and importers recommending they adhere to UL safety standards, a well-respected stamp of approval governing consumer products.
The commission is hosting a hearing on lithium ion battery safety on Thursday. Fritz, who is testifying, said he expects federal regulation will come eventually.
In the meantime, the current wave of fires has cost lives, property and money. A January presentation from the Department of Energy Storage and Electric Transportation at the Idaho National Laboratory notes that automakers and insurance companies could face warranty- and liability-related financial losses, and losses from negative public perception of electric vehicles.
New York City Mayor Eric Adams recently signed a law that requires micromobility devices sold in the city to meet UL standards. That rule goes into effect in September, although noncompliant micromobility devices can still be bought outside the city and brought in.
Still, the changes are having an effect, said Robert Slone, senior vice president at UL Solutions.
“Brands you would recognize, for sure, are bringing their e-bikes in for testing and certification at a much greater pace than they did before because of the law,” he said. “So I am encouraged that we are going to get to a better place.”
Slone said he has not seen any case where UL-certified batteries have caught fire, but he and others warn that, as in the case of combustion engine vehicles, even quality products will likely have issues. Slightly more than 25 electric vehicles catch fire for every 100,000 sales, compared with nearly 1,530 gasoline cars for every 100,000 sales, according to a study by AutoinsuranceEZ using data from the National Transportation Safety Board and the Bureau of Transportation Statistics.
Batteries degrade naturally over time. Crashes happen. But better standards and public education are key to longevity for this still-new technology.
“All of the information that we’ve learned relative to gasoline and how to manage gasoline and how to store gasoline, we’re at day one with respect to lithium ion batteries,” said Fritz. “I mean, I’ve got two cars in a garage underneath my bedroom and I sleep like a baby every night.”