American Airlines is the latest airline to update its portable charger rules, limiting travelers to a maximum of two devices. The new policy requires customers to keep their devices in plain sight during flight and is aimed at supporting safety and security. The Federal Aviation Administration has issued a safety alert regarding the risks of lithium powered batteries, which have caused flight diversions and injuries. Currently, passengers are allowed to bring up to four spare lithium-ion batteries, with two batteries being between 100 and 160 watts. The policy also applies to passengers who violate this could face a prison sentence of up to two years or a $6,300 fine.