"Allowed as Carry-On" but Charging is a No-Go? The Changing Common Sense of Air Travel with Mobile Batteries

There is nothing more inconvenient during travel than a smartphone running out of battery. Displaying boarding passes, checking train schedules upon arrival, and confirming directions to the hotel are all crucial tasks. Many people carry a portable battery in their bags as a safety measure.

However, just because you can bring it on a plane doesn't mean you can use it.

On October 17, 2026, the German newspaper Hamburger Abendblatt highlighted the underestimated fire risk of portable batteries on airplanes. The article begins by noting a series of fire incidents, with Lufthansa acknowledging an increasing trend.

This is not just an issue overseas. In Japan, new rules regarding the number of batteries you can bring and charging them onboard have already been implemented. Before traveling, it's essential to check not only the battery level but also how to handle them.

Changes have also been made in Japan: "Up to 2 units" and "No charging" are the basics

The Ministry of Land, Infrastructure, Transport and Tourism changed the rules regarding bringing portable batteries on planes starting April 24, 2026.

The main additions are as follows:

• You can bring up to two portable batteries per person, each under 160Wh.
• Do not charge the portable battery itself onboard.
• Do not charge electronic devices like smartphones from the portable battery onboard.

The existing rule that portable batteries cannot be placed in checked luggage continues.

A common confusion is the difference between "bringing" and "using." You can bring products that meet the conditions to your travel destination. However, you cannot connect and charge your smartphone battery just because it is running low onboard.

JAL officially announced this change, and ANA has also notified changes regarding the number of items you can bring and charging. Memories of being able to use them during previous flights are not a basis for current decisions.

Regulations are also tightening in Europe. Lufthansa restricts storage locations

The Lufthansa Group banned the use and charging of portable batteries on their group airlines' flights starting January 15, 2026.

You can bring up to two units per person. They cannot be placed in overhead compartments and must be stored in designated locations such as the pocket of the seat in front, on your person, or in carry-on luggage under the seat.

The basic capacity limit is 100Wh, and anything exceeding that up to 160Wh requires prior approval from the airline. Exceptions are made for powering essential medical devices, but this is distinguished from charging general smartphones.

The International Civil Aviation Organization (ICAO) also introduced standards on March 27, 2026, limiting passengers to two portable batteries and prohibiting recharging the battery itself during flights.

However, this international standard announcement does not mean that the usage conditions of airlines worldwide have become completely uniform. It's necessary to check the airline's guidance for power supply from the battery to other devices and storage locations.

Why are small batteries a problem?

Lithium-ion batteries used in portable batteries are a convenient technology that stores energy in a small body. However, they can experience "thermal runaway," where abnormal heating progresses due to damage, overheating, overcharging, or manufacturing defects.

The Federal Aviation Administration (FAA) explains that lithium-ion batteries have the potential for overheating and thermal runaway. Just because they are not in use does not mean they are always safe.

In aircraft, it is crucial to notice abnormalities quickly and have trained crew members respond. The background to prohibiting storage in checked luggage and requiring them to be carried into the cabin is to facilitate this response.

Furthermore, it is difficult to detect heating or swelling in bags placed deep in overhead compartments. The Lufthansa Group's regulations on storage locations also indicate that "where to place them" is part of safety management.

The danger is not only in using them in specific situations. Care must be taken when carrying them in a state where abnormalities are easily overlooked.

On social media: "Safety is important, but can we use power?"

Regarding the tightening of regulations, travelers' confusion is also evident on social media and online forums.

On the English-speaking forum Reddit, a February 2026 post about Japan's regulatory changes included comments clarifying that bringing them is not prohibited, but using them onboard is. Some opinions suggest that it is not a major issue for short domestic flights.

On the other hand, concerns about seat power are prominent. Experiences of loose plug connections and equipment without power availability are shared, with replies noting no issues on their flights. User experiences vary.

In an April 2026 post related to travel in Japan, a traveler wanting to use a handheld game console on a long-haul flight expressed concern about the battery not lasting without a portable battery. In another post about Lufthansa's regulations, there were complaints about whether the onboard USB power could provide the necessary output.

These are not direct responses to the original article but posts about related onboard regulations. They include the poster's experiences and speculations and do not represent official airline rules.

Nevertheless, it is clear that travelers are troubled. Even if they understand safety measures, the issue of how to secure the necessary power during long journeys remains. Along with spreading awareness of the regulations, airlines need to clearly communicate the availability and conditions of seat power.

"W" and "Wh" are different. Let's review capacity displays

On social media, there are questions about whether a product with an output of "165W" exceeds the "160Wh or less" restriction.

These two numbers may seem similar but are different.

W (watt) is a unit that represents power, indicating the output size for chargers, etc. Wh (watt-hour) represents the amount of energy stored, which is what you check for capacity restrictions in air transport.

Therefore, you cannot judge based solely on appearance or output, thinking "high output products cannot be brought" or "small ones are fine."

First, check the Wh display on the body or manufacturer materials. If you can't read the display or don't know the capacity, it's more reliable to inquire with the airline before boarding. You also need to check the upper limit you can bring and the conditions requiring prior approval.

If you notice an abnormality, don't wait for smoke

The FAA advises that if a battery or electronic device becomes unusually hot, swells, emits smoke, or catches fire, you should immediately inform the crew.

If you put it back in your bag thinking "let's wait and see," it becomes difficult to grasp changes. It's important to inform early and follow instructions rather than proceeding with self-judgment.

Additionally, you should not take products that are already swollen, damaged, or subject to recall on your trip as they are.

When packing, protect the terminals from touching metal objects. ANA advises insulating measures such as covering the terminals with tape or placing them in a bag. Also, remember to remove the portable battery if you suddenly need to check your hand luggage at the boarding gate.

Preparing for air travel changes from "I'm fine because I have a backup power source"

For future travel, preparation that does not assume the use of portable batteries onboard will be helpful.

Charge smartphones and other devices before departure. For long-haul flights, check if the equipment you plan to use has seat power and prepare the necessary cables. However, consider equipment changes or malfunctions and plan to save battery for use after arrival.

Portable batteries remain a convenient tool to use at your destination. However, onboard, you need to check the conditions for carrying, using, and placing them.

Don't rely on "it was fine before," and review official guidance before departure. This extra step contributes to the safety of yourself and other passengers.

*Regulations are based on information confirmed as of October 18, 2026. Please follow the latest guidance from the airline operating your flight and the instructions of the crew.

Sources and References

1. Hamburger Abendblatt:
   Article dated October 17, 2026, addressing the risk of portable battery fires onboard.
   https://www.abendblatt.de/hamburg/wirtschaft/article413401375/powerbank-in-flugzeugen-feuer-gefahr-lufthansa-eurowings-swiss-indigo-regelungen.html

2. Ministry of Land, Infrastructure, Transport and Tourism: Japan's new rules from April 24, 2026
   Check the number of items, capacity, onboard charging restrictions, and background of system changes.
   https://www.mlit.go.jp/report/press/kouku10_hh_000310.htmlMinistry of Land, Infrastructure, Transport and Tourism

3. JAL: Announcement of changes regarding the number of items you can bring and charging
   Check the guidance on 2 units per person, under 160Wh, prohibition of checking in, and onboard charging.
   https://www.jal.co.jp/jp/ja/info/2026/other/260330/jal.co.jp

4. ANA: Changes in handling portable batteries
   Check the conditions for carrying, onboard charging, and terminal insulation measures.
   https://www.ana.co.jp/ja/jp/special-notice/001379.html?p1=top&p2=ja&p3=globalana.co.jp

5. Lufthansa Group: Regulations from January 15, 2026
   Check the prohibition of use and charging, storage locations, capacity and prior approval, and exceptions for medical devices.
   https://business.lufthansagroup.com/ie/en/program/experts/news/power-banks-on-board--updated-regulations-from-january-2026Lufthansa Group

6. ICAO: Changes in international standards for portable batteries
   Announced on March 27, 2026. Check the limit of two portable batteries per passenger and the prohibition of recharging the battery itself during flights.
   https://www.icao.int/news/new-power-bank-restrictions-will-safeguard-international-aviationicao.int

7. FAA: Safety information on air transport of lithium batteries
   Check the causes of thermal runaway, notifying crew in case of abnormalities, short-circuit prevention, damaged/recalled products, and explanation of Wh.
   https://www.faa.gov/hazmat/packsafe/lithium-batteriesFederal Aviation Administration

8. Reddit: Traveler reactions to Japan's regulatory changes
   Refer to posts and comments on the differences between bringing and using, and the usability of seat power.
   https://www.reddit.com/r/JapanTravelTips/comments/1r8fl69/reddit.com

9. Reddit: Questions about capacity display and charging on long-haul flights
   Refer to concerns about confusion between W and Wh and battery life for handheld game consoles.
   https://www.reddit.com/r/JapanTravelTips/comments/1sz9rvp/reddit.com

10. Reddit: Reactions to Lufthansa's prohibition on use
    Refer to concerns about the output of onboard power by users of handheld game consoles.
    https://www.reddit.com/r/LegionGo/comments/1qh8rq6/