A lithium-ion battery. Photo: RNZ / Kim Baker Wilson
Fire and Emergency are warning people to be mindful of the products they purchase over the summer period with lithium batteries after the number of fires has doubled in four years.
Data shows numbers have ballooned from 51 fires in 2020 to 104 this year as of 22 November.
Fire and Emergency said although they did not have any evidence on what could be behind the increase, it was putting it down to more lithium-ion battery products on the market.
Lithium-ion batteries are in many everyday products, including e-scooters, phones and vapes.
FENZ community education manager Tom Ronaldson said if not looked after or dealt with properly, lithium-ion batteries could cause damage to people's properties and their livelihoods when they go into a process called thermal runway.
"The battery gets really, really hot, and the fire can spread incredibly fast.
"So if someone was to experience a battery that was making a strange sound or overheating or on fire or emitting smoke, we recommend that you evacuate immediately and call 111," Ronaldson said.
In March 2024, Island Bay resident AJ Hunter was woken by his wife at 4am after his neighbour's Tesla spontaneously combusted with the blame being pointed to its lithium-ion battery.
"I had a look out the window and seen the biggest fireball I'd ever seen in my life, freaking out, jumped out of bed, put some shoes on, starting running up the street," Hunter said.
Crew from four fire engines took an hour to extinguish the blaze, which destroyed three garages.
Hunter said fire fighters had told him the blaze was caused by the car's lithium-ion battery.
"The Tesla in the central garage caught fire and that had burnt down the two garages next door - [it] was quite terrifying.
"Supposedly, the lithium-ion battery in the Tesla had gone in to thermal runway so somehow they were either damaged or overheated and that caused the whole vehicle to spontaneously combust," Hunter said.
A neighbour's 30-year-old Rover restoration project they were working on was also destroyed in the blaze, he said.
Ronaldson advised consumers to buy quality products that were from reputable suppliers.
"We recommend that people buy any products that have lithium-ion batteries from trusted retailers and when they're buying replacement batteries for products making sure that they are getting the batteries from the manufacturer and not from a second-hand dealer.
"We want to make sure that the batteries are fit for purpose for that device and not potentially going to get damaged from having that greater wattage or power output," Ronaldson said.
Although the batteries themselves were safe, he said, it was up to buyers to use the correct cords and power bank to prevent any fires because of the high voltage the product may have.
He advised people to also replace damaged or dropped products, especially if the battery became hot or if users noticed the power bank had swollen.
"We've seen a number of fires [in] rubbish trucks, so we recommend that people find the battery disposal or battery recycling centres to dispose of batteries rather than just throwing them in the rubbish bin," Ronaldson said.
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