Crucial Regulation Updates for Portable Lithium-Ion Batteries on Japanese Airlines

For international travelers, smartphones are essential tools for navigation and translation. Consequently, portable mobile batteries (power banks) have become a standard travel item. However, starting in mid-April, the Japanese government will implement stricter safety regulations regarding the transport and use of these devices on all domestic and international flights within Japan.

The Ministry of Land, Infrastructure, Transport and Tourism (MLIT) is currently revising the public notice related to the Civil Aeronautics Act. These changes align with updated international safety standards expected to be finalized by the International Civil Aviation Organization (ICAO) by March.

Primary Regulatory Changes

The upcoming revisions focus on two significant areas of passenger conduct and safety.

1. Quantity Restrictions: The Two-Battery Limit

Current regulations permit an unrestricted number of batteries with a capacity below 100 Watt-hours (Wh). Under the new rules, this will change the followings:

Regulation Aspect	New Rule / Requirement
Individual Capacity Limit	Max 160 Wh per battery (must be below this)
Quantity Cap	Maximum of two portable batteries per person
Scope of Limit	Applies to the combined total of “spare batteries” and “mobile batteries”
Carry-on/ Checked	Must be carried in carry-on baggage (prohibited in checked luggage)

• New Quantity Cap: Regardless of individual capacity (provided they remain below the 160 Wh threshold), passengers are limited to a maximum of two portable batteries per person.
• Combined Total: This limit applies to the combined total of “spare batteries” (such as those for cameras or laptops) and “mobile batteries” (power banks). While spare batteries below 100 Wh do not have an independent count limit, the presence of a mobile battery restricts the total combined count to two units.
• Carry-on Requirement: Portable batteries remain strictly prohibited in checked luggage. They must be kept in carry-on baggage to ensure they can be monitored by the owner.

2. Restrictions on In-Flight Use and Charging

The new guidelines introduce a significant shift in how these devices can be used during flight.

• Charging Prohibited: It is explicitly forbidden to charge a mobile battery using the aircraft’s onboard USB ports or seat power outlets.
• Usage Discouraged: The new regulations strongly discourage the use of power banks to charge other electronic devices during the flight. Japanese airlines will request that passengers refrain from using these batteries entirely while on board, effectively creating a de facto ban on in-flight usage.

Safety Rationale

The tightening of these rules is a direct response to a rising number of safety incidents. The National Institute of Technology and Evaluation (NITE) reported that accidents involving lithium-ion batteries in Japan reached 123 cases in 2024, approximately 2.6 times the number recorded in 2020.

Recent aviation incidents further justify these measures. In 2023, a mobile battery on an Air Busan flight caught fire, resulting in 27 injuries. Similar incidents involving smoke or fire were reported on Hawaiian Airlines and All Nippon Airways (ANA) flights within the past year. Because lithium-ion batteries are prone to overheating if damaged, constant monitoring is required.

Travel Recommendations

To ensure a smooth travel experience under these new regulations, travelers are advised to adhere to the following practices:

• Pre-Flight Charging: Ensure all electronic devices are fully charged before boarding.
• Utilize Airport Infrastructure: Take advantage of charging stations available in departure lounges prior to boarding.
• Direct Charging: On aircraft equipped with seat power, charge devices directly using a wall adapter and cable. The restriction specifically targets the use of mobile batteries as a power source or the charging of the battery itself.

While these regulations may pose an inconvenience, they are critical for maintaining aviation safety. Travelers should always verify the latest specific rules on their airline’s official website prior to departure.

Conclusion: A Manageable Shift for Most Travelers

While these revised regulations may appear stringent, for the vast majority of international travelers, the impact on their journey will be minimal. The 160 Wh capacity limit remains generous, accommodating all standard mobile batteries. 

Furthermore, the new two-battery limit primarily formalizes a practice already common among careful flyers. The key behavioral adjustment is the restriction on in-flight usage and charging. Simply ensuring devices are fully charged before boarding and utilizing airport amenities, travelers can easily manage their power needs.