Connecting your external battery to your smartphone as soon as the in-flight Wi-Fi is activated has become a reflex on long hauls. But if your plane takes off or lands in Japan, this trivial act can now be considered a criminal offense, with very heavy penalties.
Since April 24, 2026, the Japanese Ministry of Transport has strictly regulated the use of external batteries on board. The rule is simple but radical: on all flights departing from or arriving at a Japanese airport, whether domestic or international, using a power bank in the sky is no longer tolerated. In the most serious cases, the law provides for up to two years in prison.
Japan aircraft external battery: what are you really risking on board?
The device directly targets external batteries that are used to recharge smartphones, tablets or PCs. Three prohibitions apply: it is prohibited to power a device with an external battery during the flight, prohibited to recharge the external battery from an outlet or USB port on the aircraft, and prohibited to carry more than two batteries per person.
Japan also sets a technical limit: each battery must have a capacity less than or equal to 160 Wh, or approximately 43,000 mAh. Most consumer models (10,000 or 20,000 mAh) remain well below, but large units for PCs or photo setups can come close.
Batteries must remain in the cabin, within reach. Already since July 2025, it has been prohibited to place them in the hold or in the luggage compartments above the seats. Any passenger caught using an external battery in flight, or carrying more than two power banks, faces a penalty of up to two years in prison or a fine of 1 million yen, or more than 5,000 euros.
Why have power banks become the bane of aviation authorities?
Behind this toughening, there is a real security issue. Japan recorded 123 battery-related incidents in 2024, an increase of 160% compared to 2020. The most notable episode remains the fire that occurred in January 2025 on board an Air Busan A321, at Gimhae airport in South Korea, after a defective portable battery ignited. The plane was seriously damaged and all passengers had to be urgently evacuated.
Lithium-ion batteries, found in our smartphones, laptops and external batteries, contain a highly flammable electrolyte. In the event of shock, fault or overload, an internal short circuit can trigger a “thermal runaway”: the cell overheats until it catches fire. The phenomenon remains rare, but at 10,000 meters altitude, even an isolated incident becomes critical.
The International Civil Aviation Organization also adopted new emergency standards for these batteries in March 2026, which Japan was one of the first to transpose. In Europe, companies like Lufthansa or Air France already apply similar rules: two external batteries maximum, limited capacity and a ban on using or recharging them in flight.
How to continue to charge smartphones and consoles without breaking the law?
If you are flying to or from Japan, the strategy is clear: you can carry a maximum of two compliant batteries, switched off, stored in your bag within easy reach, but you do not use them during the flight. To keep your smartphone, Nintendo Switch or laptop powered on, you should use the power outlets or USB ports integrated into the seat, when available.
Before boarding, remember to charge all your devices to 100% in the terminal or hotel, and activate airplane mode and dimming to last longer. For mobile gamers, it is better to plan a few games that can be played offline and limit streaming, which consumes a lot of energy.
Given the pressure from ICAO and the first movements in Japan, Singapore and Europe, everything indicates that the use of external batteries in mid-flight will be increasingly restricted everywhere. It is therefore better to adapt your habits now rather than test the patience of the Japanese airport police.