Due to safety concerns, American Airlines has tightened its rules for traveling with portable chargers that run on lithium batteries.
Effective Friday, May 1, each passenger is limited to two portable charging devices, neither of which can exceed 100 watt hours, according to reports.
What's more, passengers will need to keep their chargers visible and within reach throughout flights—no storing the devices in overhead bins and no recharging power banks using in-seat outlets allowed.
The concern is that lithium batteries can overheat and potentially cause fires—a problem with the risk of especially dire consequences if batteries are smoldering out of view in overhead bins or plane cargo holds (the Federal Aviation Administration already bans personal chargers from checked luggage).
If a device gets too hot or starts to smoke in an airplane cabin, flight crews are trained to deal with the situation, but it helps if they can see there's a situation that needs dealing with before it's too late.
Airlines around the world have enacted stricter policies on chargers in recent months.
A week before American's move, Southwest Airlines began enforcing a similar policy, though Southwest limits passengers to one portable charger or power bank per passenger, whereas American allows two.
The policies recently adopted by United Airlines and Delta Air Lines are akin to American's new rules around chargers, albeit with minor variations here and there.
Be sure to check your chosen carrier's instructions for flying with power banks and other electronic devices before you start packing for a trip.