Fires caused by lithium-ion batteries are presenting an unprecedented challenge for New York City firefighters who are battling an increasing number of these blazes that quickly get out of control and are stubbornly hard to extinguish.

In large part, the technology that is used to manufacture the type of rechargeable battery commonly used in electric bikes and electric scooters makes the batteries dangerous to handle when they catch on fire.

“We are in a crisis mode right now when it comes to the batteries,” City Councilman Keith Powers said at a Committee on Fire and Emergency Management hearing last month.

Lithium-ion batteries caused 220 fires in the five boroughs last year, up from 44 in 2020, according to the FDNY. These fires resulted in 147 injuries and six deaths in 2022, 32 injuries and two deaths more than the previous three years combined.

And so far this year, lithium-ion batteries have already sparked 68 fires that have led to 56 injuries and five deaths, the FDNY said.

Experts say the components of the batteries are built in a way that simply dousing the unit with water, foam or any other typical materials firefighters use will not put out the fire.

A normal campfire, for example, can be extinguished with water, which separates the oxygen and the fire’s source of fuel, cooling the flames and removing its heat. But a lithium-ion battery has various internal pieces that start to decompose and become very reactive when exposed to high temperatures.

“In a lithium-ion battery, all that stuff is happening internally and you can’t separate that process as easily,” said Ofodike Ezekoye, an engineering professor at the University of Texas at Austin. “If you were to put water on a battery that is on fire, you’re not getting the water deep inside the battery pack.”

This means that by the time help arrives, it is oftentimes too late. And to make matters worse, in many lithium-ion battery fires, the battery fails without warning and explodes.

This happens largely because of human error — people use uncertified, used batteries, charge their bikes and scooters with a charger not originally intended for the device or continue to use their battery after a crash damages the unit’s internal components, experts say.

“People are involved,” Ezekoye, a lithium-ion battery expert who has published more than 200 scientific articles on combustion, heat transfer and battery failures, said. “You can’t imagine all the goofy ways people are going to misuse their products. It is human failure, which is the nature of these types of systems.”

And when failure occurs and a battery ignites, the flames can quickly reach more than 1,000 degrees Celsius, and the battery simply has to burn out.

“At best, a firefighter can cool down the sofa the battery is near or the mattress or whatever sort of normal combustible material there might be in that room, so that those don’t catch on fire. But the battery is very, very deep,” Ezekoye said.

Last month, a lithium-ion battery ignited inside a Bronx grocery store, shooting toxic chemicals into aging lumber and instantly creating a dangerous situation for many nearby.

The FDNY responded to the scene in just four minutes, but the fire had already spread out of control, and within hours, the supermarket and a nearby laundromat were destroyed.

“It’s really something we’ve never seen before, as far as a small fire turning into something like this in a matter of a few minutes,” FDNY Chief of Department John Hodgens said at a press conference after the fire.

One reason why lithium-ion battery fires are a big problem in the city is because there are so many people who use e-bikes and e-scooters.

There are more than 65,000 app delivery workers in New York City who use e-bikes and e-scooters for their deliveries, according to the Hunter College New York City Food Policy Center.

Over the years, the devices have become popular as a way to weave through tight streets and dense traffic more easily than driving a car.

However, e-bikes and e-scooters that are properly certified are very expensive, with some retailing for up to $2,500. That makes used, uncertified and secondary market batteries — which are much cheaper — a popular option for delivery drivers, according to a local expert who worked with the city to come up with new safety standards.

“These batteries are very important to their livelihood. And I sincerely mean it when I say that safety is not a luxury good. We know that certifications need to be cost-effective in the future,” said Robert Slone, senior vice president and chief scientist of UL Solutions. “We do not want to price people out of their livelihood. We know that this has to work financially for everyone.”

Mayor Eric Adams signed off on a package of legislation in March that attempts to reduce the risk of fires caused by lithium-ion batteries. Slone says the laws will take effect in September.

One of the five bills will ban city businesses from selling, leasing and renting out new devices that do not meet industry safety standards.

“Before that, it was all voluntary certification. And as you might imagine, voluntary is effective only to a certain status,” Slone said. “Once it’s required, there’s a different level of conformance to the law and to the standards. So this is really huge.”

A second bill will ban manufacturers and businesses from assembling and selling batteries that contain cells from used devices, which are much more likely to malfunction. Other bills will require the FDNY to file reports compiling e-bike and e-scooter fire data and fire prevention recommendations, and also focus on public safety outreach.

And Slone says these guidelines could serve as a model to other governments around the world also seeing an uptick in lithium-ion battery fires.

“We’ve had contact from government agencies elsewhere around the world, whether it’s Europe or Australia, asking about our new laws,” Slone said. “These fires are everywhere, but New York City really stepped forward first with legislation.”