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Firefighters called after overheating mobile battery placed in hotel fridge in Hokkaido

Master Blaster Aug 30, 2025
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But is the fridge to blame?

At about 7:00 a.m. on 24 August, firefighters were called in to a hotel in Rumoi, Hokkaido, after an employee noticed smoke coming from one of the rooms. When they arrived, the smoke had already dissipated and the man in his 40s, who was staying in the room at the time but unharmed, explained that it was his mobile battery that had overheated.

According to a police investigation, the man was charging his battery in the room when it began to get very hot. He decided to place it in the refrigerator to cool it down, but smoke started to seep out from it. By the time the fire department arrived, a part of the battery had melted.

In online comments, readers of the news seemed in disagreement whether putting the overheating battery into the fridge made things better or worse.

“That’s why I started using a battery with a cooler.”
“I always keep a fan blowing on my battery.”
“If it already started heating up internally, would a fridge even help?”
“The fridge stopped the fire from spreading, so it was at least good for that.”
“Did the fridge make it burn up?”
“What is the correct thing to do when that happens?”
“You should put it in a sink filled with water or the toilet.”
“Putting it in the refrigerator doesn’t matter.”
“You have to be careful with those. My friend said he bought an Anker, but when I looked at it, it was an Auker.”
“It’s certainly hot enough for a battery to catch fire.”

The key in judging the man’s action is knowing when what appears to have been a thermal runaway occurred. This is when something causes the battery to get so hot it makes the cells rupture, and the chemical reaction from that generates more heat, which creates a chain reaction that is very difficult to stop and can result in a fire or explosion.

You could argue that if the battery was already in a state of thermal runaway, putting it in the fridge would at least keep it away from flammable things like wooden tables or sheets. The ideal place would be anywhere outdoors so the gases can vent safely, but in a hotel room, that’s often not an option.

The bathtub, provided it’s dry, would be good too because bathrooms usually have separate vents to suck out the smoke and gases. At this point, the choice between the fridge and the bathtub would be whichever the hotel charges you more to replace.

▼ Completely submerging it in a toilet or sink, as some suggested, would also result in a chemical sludge that would likely lead to a costly cleanup. There are also shock and explosive hazards involved, so it is not recommended.

So, if the battery were already in a thermal runaway, then he made a pretty good choice by tossing it in the fridge to reduce the chances of wider damage or even a full blown fire.

However, if the battery was just hot but stable, he might have inadvertently triggered a thermal runaway by putting it in the fridge. The danger here is that putting a hot battery into a cold fridge might cause condensation to form inside it. This moisture could cause the cells inside to short and trigger a thermal runaway.

Ways to tell if thermal runaway is occurring include very rapid heating, as well as strange sounds, smells, or bulging from the device, but that isn’t always easy to notice in the literal heat of the moment.

All things considered, putting it in the bathtub, or a dry spot on the tile floor if the tub is wet, would have been the best choice because it would have covered his butt whether a thermal runaway was happening or not. If not stuck in a hotel room, you’d be best to find a patch of concrete or metal outdoors and away from anyone or anything flammable and stand back until it either cools down or blows up.

Let’s stay safe out there with all these explosive devices in our pockets!

Source: STV News, Itai News
Featured image: Pakutaso
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