Passengers flying with low battery on their phones might be out of luck—at least if they are flying American Airlines. The country’s largest airline is implementing a new policy that will restrict how many portable chargers passengers may bring to the aircraft, citing potential safety concerns from lithium batteries. “We know our customers rely on portable chargers to keep devices powered throughout their journey,” the carrier told CBS . “To support safety on board while ensuring our customers continue to have the ability to charge when on the go, American is requiring customers to keep these devices easily accessible during flight.” The new policy goes into effect on May 1, requiring passengers to bring no more than two portable chargers, which are to be kept visible at all times, even when not in use to allow flight attendants to address an incident promptly. The regulation now prohibits batteries from being stored in the overhead compartments, and outlines the power capacity allowed for portable chargers, capping it at 100 watt-hours.  According to the Federal Aviation Administration, there have been at least 717 lithium battery incidents in the last couple of decades, 548 of which occurred in passenger aircrafts. The incidents may look like smoke, fire, or extreme heat caused by thermal runway , meaning a  sudden and uncontrollable increase in temperature. The rule applies not only to small portable chargers often used to power phones, computers, and tablets, but also other power banks using a lithium battery, like ones incorporated into backpacks or luggage. The decision is also not the first in the industry. Southwest Airlines also only one portable charger per passenger can board their aircrafts. That decision came into effect earlier this month. While slightly inconvenient to passengers who travel with portable batteries, many users online highlighted the importance of implementing such rules. “As someone who witnessed with their own eyes a lithium battery in the overhead bin being on fire less than a month ago…as a flight attendant for the sake of my safety & others I beg everyone to follow these rules,” a user said on X .