Lithium ion battery causes house fire in Sanbornton Saturday

SANBORNTON — One person suffered minor burns from a weekend house fire. An investigation determined the cause was a backup lithium ion battery system. Firefighting crews from nine communities responded to the fire on Saturday.

“It’s similar to a standby generator,” explained Sanbornton Fire Chief Paul Dexter Jr. “They had a transfer switch for when they lose power.” 

The owner and sole occupant of the house had just reset the batteries after her home regained power on Saturday. 

“She went back to cycle the batteries off, did that, left the room then heard popping,” Dexter said. “That’s when, in her words, the batteries were ‘bubbling.’”

According to a written statement from the fire department, “this phenomenon is known as a 'Thermal Runaway', which is one of the primary risks related to Lithium-ion Batteries.”

The owner immediately called 911 as the fire overtook the mechanical room and the garage of the home. As the flames grew, the owner suffered minor burns and smoke inhalation as she attempted to move her vehicles from the burning garage.

Crews used tankers with 1,000 feet of four-inch supply hose to douse the home. Such actions are par for the course in rural communities like Sanbornton.

The town fire department is not responsible for electrical inspections.

“I only inspect gas, natural gas or oil" systems, explained Dexter. “With generators, we only inspect the gas fitter portion of it.”

Dexter said that those in need of an electrical inspection in Sanbornton should go through the state electrical board.

According to Dexter, the homeowner was released from Concord Hospital—Laconia and will be staying with family members through the holiday season. 

The system "was done by a licensed electrician,” Dexter said. “The problem being, is lithium ion batteries, if they get in that runaway mode, they continue to create heat and power.”

The garage and the kitchen were considered a complete loss due to the damage, but crews managed to save a portion of the home.

According to the written statement, the roof of the garage collapsed within two minutes of arrival of the first fire companies. “This we believe is due to the failure of the roof truss system based on the fire load and the weight of the 24 solar panels on the south facing side of the garage roof,” wrote Deputy Chief Scott Taylor.

“Luckily my crews were able to keep [the fire] from getting inside the east part of the house,” Dexter said. “She had her bedroom door closed which kept the damage to her bedroom minimal.” 

In addition to the house damage, fire crews found an unknown substance in and around the garage that had to be identified by the Department of Environmental Services. The DES spill control team identified the substance as iron sulfate heptahydrate, which Taylor described as “a product used in battery storage for solar panels.”

As of Wednesday, the fire department was working with the property owner and DES to find a cleanup solution. 

For Dexter, this situation was a surprising first. 

“I’ve been in the fire service 37 years and I’ve never had a dealing with a battery system in a home,” Dexter said. “I’ve been to a ton of car fires caused by batteries including some electric cars, but never a residential home.”