[Economic Report] [Rapid Increase in Fires] Is Your Mobile Battery Safe? 3 Safety Rules to Prevent Ignition [April 2026]

As a companion to our smartphones, the "mobile battery" has become indispensable to our daily lives. However, did you know that in recent years, fire accidents caused by these small partners have been increasing rapidly in Japan as well?

"It suddenly caught fire and started smoking inside my bag."
"It swelled up while charging and a small explosion occurred."
"I was charging it in the bedroom and the fire spread to the futon."

Terrifying cases like these have actually been reported. In this article, we will explain in an easy-to-understand way why mobile batteries catch fire and the three rules for using them safely.

■ 1. Why do small batteries burn?
The cause lies in the mechanism of the "lithium-ion batteries" used inside. These batteries are very convenient because they can store a large amount of energy in a small box.

However, they are also delicate; if they receive a strong impact or an internal short circuit occurs, the energy can run out of control, leading to high temperatures, which can result in ignition or explosion.

■ 2. Are you doing these dangerous, bad habits?
Small, everyday actions can trigger accidents.

・Throwing it carelessly into a bag (can cause a short circuit by coming into contact with keys or coins)
・Using overly cheap, non-branded products (there is a possibility that the internal safety design is poor)
・Charging on a futon, sofa, or inside a car (heat gets trapped, which is extremely dangerous)

Also, if the battery is "swollen," it is a super dangerous sign that gas is accumulating inside! It is in a state where it could burst at any moment.

■ 3. Prevent accidents! 3 safety rules
To continue using your mobile battery safely, let's follow these three rules.

① Choose products from reliable manufacturers (PSE mark)
Even if they look similar, there is a big difference in the internal components that prevent runaway in the event of an abnormality. When in doubt, you can rest assured by choosing products that have the "PSE mark," which meets Japan's safety standards.

② Charge in a place where heat does not accumulate
Avoid charging inside a futon or in a car, and please charge in a place with good airflow where heat can easily escape.

③ If you feel something is wrong, "have the courage to dispose of it"
If you feel it is "swelling," "smells like it is burning," or is "unusually hotter than usual," stop using it immediately. Do not think it is a waste; consult your local government's battery collection box or a retailer and dispose of it safely.

■ Conclusion
Mobile batteries are convenient tools that support our lives, but they also have a dangerous side if you make a mistake. Understand the correct way to use them and lead a safe and comfortable digital life!