Rules for Portable Batteries on Planes Are Changing. Here’s What to Know.

The rules around flying with portable batteries are becoming increasingly confusing as some airlines in Asia change their policies, citing the risk of fires.

Airlines in South Korea, Taiwan and Thailand have tightened restrictions since a fire destroyed an Air Busan plane on the tarmac in South Korea in January, one of several recent aviation accidents that have made travelers anxious.

There is no definitive link between portable batteries and the Air Busan fire, and an investigation is underway. But because rules vary across airlines, you may find yourself having to repack or turn off such batteries when you board a plane. Here’s what you need to know.

Which airlines have changed their rules and why?

As of March 1, passengers on all South Korean airlines must keep their portable chargers within arm’s reach and out of overhead bins. The government implemented the rule to ease anxiety about the risk of battery fires, the Transportation Ministry said.

Some Taiwanese airlines implemented similar changes that also took effect on March 1. EVA Air and China Airlines announced a ban on using or charging power banks on their planes, although the batteries can still be stored in overhead compartments.

Thai Airways, Thailand’s flagship airline, announced on Friday that it would implement a similar ban. The airline cited “incidents of in-flight fires on international airlines, suspected to be linked to power bank usage.”

Since 2016, the International Civil Aviation Organization, the United Nations agency that coordinates global aviation regulations, has banned lithium-ion batteries, the kind commonly found in power banks, from the cargo holds of passenger planes.

But there is no industry standard on how airlines regulate power banks, said Mitchell Fox, the director of the Asia Pacific Center for Aviation Safety.

They have become a part of everyday life only in recent years, and some consumers may be unaware of the risks, he said. “When you have an emerging issue, it takes a while for everyone to catch on.”

What are the risks behind these batteries?

Lithium-ion batteries have been used for decades to power smartphones and laptops, and are commonly used in portable power banks.

Each lithium-ion battery has a cell that can heat up quickly in a chain reaction that causes it to catch fire or explode. The Federal Aviation Administration warns that this reaction can happen if the battery is damaged, overcharged, overheated or exposed to water. It can also happen if the battery has a manufacturing defect.

Some products that use lithium-ion batteries, including smartphones, laptops and electric vehicles, have strict regulations and quality control standards, said Neeraj Sharma, a professor of chemistry at the University of New South Wales in Sydney, Australia, who studies batteries. Others, like power banks, e-cigarettes and vehicles such as e-bikes and scooters, are less regulated, he said, raising the risk of malfunction.

“Make sure you get your devices from reputable manufacturers,” Professor Sharma said.

How often do batteries catch fire on planes?

Incidents involving lithium-ion batteries on U.S. airlines have been increasing. There were 84 last year, up from 32 in 2016. These included cases — in the cabins of both passenger and cargo planes — where batteries caught fire, emitted smoke or overheated. Portable chargers were the biggest culprit in these incidents, followed by e-cigarettes, according to the F.A.A.

Airlines around the world require passengers to pack spare lithium-ion batteries in their carry-on luggage instead of in their checked bags so that any smoke or fire from the batteries can be noticed quickly. In the cargo hold, a fire may not be detected by a plane’s automatic fire-extinguishing system until it has already become a critical problem.

“If there is a fire, you’d rather have it in cabin than checked baggage, and you’d rather have it closer to a person rather than in the overhead bin, where it’s more difficult to get it out and manage the fire,” said Keith Tonkin, the managing director of Aviation Projects, an aviation consulting company in Brisbane, Australia.

What do flight crews do when there is a fire?

Fires in plane cabins that are caused by lithium-ion batteries are rarely deadly, and flight crews are generally well prepared to deal with them, Mr. Tonkin said.

In many cases, passengers will notice their electronics overheating and inform crew members, who will put the device into a thermal containment bag or into water, with little disruption to the flight, according to the F.A.A. In some cases, flight attendants or passengers will notice smoke in the cabin and discover that a device has overheated or caught fire.

In 2024, two portable batteries that were connected to each other caused a fire aboard a flight from Bangkok to Seoul operated by Eastar Jet, a budget South Korean carrier, according to Yonhap, a South Korean news agency. The flight crew noticed the smoke and immediately poured water on the batteries to douse the fire, the agency reported.