‘Really hard to stop’: Lithium ion fires pose greater challenge for firefighters, expert says

QUINCY, Mass. — It is called “thermal runaway” and it’s what happens when a lithium ion battery is damaged or overheated. And it can have devastating consequences.

“Thermal runaway is when that one battery cell heats up, it spreads to its adjacent cells. and it’s really hard to stop,” said Brian O’Connor, senior fire protection engineer at the National Fire Protection Association in Quincy. “Each one of those battery cells contains a lot of energy.”

So much energy that lithium ion batteries can explode into flames.

“If it starts in the center, the perimeter gets bigger and bigger,” O’Connor said. “And it’s very hard to disrupt.”

That’s primarily because of proximity. Lithium ion batteries are usually packed together in a protected space -- to keep them from getting damaged.

Lithium ion batteries first came on the market in the 1990s. But their developmental path goes back more than 50 years, and researchers have long known their potential to cause fires.

What Massachusetts officials didn’t know -- until now -- is how often they should assign fire blame to the batteries. The answer turns out to be: more often than they thought.

Last October, the state Department of Fire Services launched an initiative to better identify lithium ion fires. Wednesday, the department released results from the first six months using the Lithium Ion Battery Fire Investigative Checklist.

And the results are troubling. From October to April, investigators identified 50 lithium ion battery fires in Massachusetts, occurring in 38 communities. Nine were triggered by batteries in mobility devices, such as electronic scooters. Cellphones and laptops accounted for eight each. Battery-powered power tools caused six.

By contrast, from 2019 to 2023, Massachusetts averaged about 20 lithium ion fires per year, the Department of Fire Services said.

O’Connor isn’t surprised.

For one thing, ownership of electronic devices continues to increase, and firefighters are gaining more experience dealing with them.

“It’s very hard to tell during a fire investigation whether the fires start from these batteries,” he said. “But fire investigators are getting better at this.”

To prevent lithium ion fires, the Department of Fire Services recommends sticking to the same brand of charger as your device, only charging directly from the wall and not with the aid of extension cords or power strips, charging devices on a less-flammable surface than soft furniture and unplugging the device when it’s fully charged.

Damaged batteries or ones that give off an odor or fail to charge, should be discarded at a recycling center. O’Connor said when you do so, it’s important to advice the recycler whether the battery is damaged or not.

“I think a lot of people aren’t aware of the fire hazard lithium ion batteries can present,” O’Connor said.

This is a developing story. Check back for updates as more information becomes available.

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