Why Are Lithium Batteries Not Allowed in Checked Luggage?

From laptops and smartphones to tablets, e-cigarettes, power banks, and electric toothbrushes, lithium-ion batteries power most of our portable devices.

While these batteries have transformed the way we charge our gadgets and use them on the go, flying with them can be complicated. Federal regulations prohibit placing them in checked baggage—they must either go in carry-ons or stay at home. But why is that?

As explained by Venkat Viswanathan, a battery expert from the University of Michigan, these batteries "pose a flight risk" because they can overheat or short-circuit, particularly if damaged. This could lead to thermal runaway, which may cause smoke, fire, and even explosions.

“If one of these batteries ignites, it could quickly set the entire cargo hold ablaze,” Viswanathan warned.

John Cox, CEO of the aviation consulting firm Safety Operating Systems and a former pilot, noted that while thermal runaway is concerning in both the cabin and cargo, if a battery begins to smoke or ignite, flight attendants can address the problem more swiftly in the cabin.

Though thermal runaway incidents are infrequent, they do occur. For example, in February 2023, a laptop ignited in the cabin shortly after takeoff, prompting the flight to return to San Diego International Airport, resulting in four flight attendants being hospitalized.

The Federal Aviation Administration reports 481 verified incidents related to lithium batteries from March 3, 2006, to August 31, 2023. Out of these, at least 343 incidents occurred in the cabin while 112 took place in the cargo hold (the remaining 26 incidents were not categorized). The most frequent issues involved battery packs (199 incidents), followed by e-cigarettes (101), mobile phones (63), other electronic devices (58), laptops (57), and medical devices (3).

Since 2014, the number of incidents has generally increased each year, with exceptions in 2019 and 2020.

From January 1 to August 23, 2023 (the latest update from the FAA’s online incident report), there were 50 incidents. In total, there were 74 incidents recorded in 2022.

Cox anticipates that the "incidence of lithium battery fires, both on airplanes and elsewhere, will keep rising due to the growing prevalence of lithium batteries in our society."

To minimize the chances of such incidents, the FAA advises travelers to check for any recalls or damages on their devices, as these factors are more likely to cause sparks or lead to hazardous heat generation.

Passengers can further safeguard themselves and others by storing their electronics in a protective sleeve or case. Excessive pressure on a device could damage the battery, potentially triggering thermal runaway; a little cushioning from a case can help avert this. Additionally, if your cell phone slips between the seats, avoid adjusting the seat—if it gets harmed, the battery could start to smoke or catch fire. Flight attendants are trained to retrieve phones safely.

Moreover, passengers can help prevent thermal runaway on planes by completely powering off devices when they are not in use.

If your device starts to overheat, smoke, or catch fire while in flight, notify a crew member immediately. They are equipped with fire extinguishers and thermal containment bags that limit oxygen to the device, preventing fire spread and neutralizing the threat.