Battery backfeed & charger bans
A utility in the Northern Mariana Islands warned customers about dangerous backfeed risks from generators and battery storage, urging safe handling and isolation. Separately, reports said Southwest Airlines and regulators are tightening rules on portable chargers after FAA battery‑fire data prompted bans on some devices. (mvariety.com) (travelandtourworld.com)
A power source can send electricity the wrong way, and two new warnings say that mistake can turn batteries and chargers into fire hazards. (faa.gov) On April 12, the Commonwealth Utilities Corporation issued a public advisory on “generator and battery storage backfeed” for customers in the Commonwealth of the Northern Mariana Islands. The utility serves Saipan, Tinian, and Rota. (cucgov.org 1) (cucgov.org 2) Backfeed means electricity flows backward from a generator or home battery into wiring that is supposed to be de-energized. Utilities warn that can energize outside lines and put repair crews and neighbors at risk during outages. (cucgov.org) (ready.gov) The airline warning is about a different battery problem: “thermal runaway,” a chain reaction in a lithium cell that drives up heat and pressure. The Federal Aviation Administration said in August 2025 that portable chargers and power banks can act as ignition sources in aircraft cabins. (faa.gov) The Federal Aviation Administration also said lithium batteries in overhead bins can be obscured, hard to reach, and harder to monitor in flight. Its guidance says crews may need large amounts of water to cool a device because halon can knock down flames without stopping the battery reaction. (faa.gov) Southwest Airlines has already tightened its passenger rules. The airline’s help page says portable chargers and power banks must stay in carry-on bags or on a passenger, must be visible when used onboard, and cannot be used to charge devices in overhead bins. (southwest.com) Southwest’s current policy allows up to 20 spare batteries, including portable chargers, in carry-on baggage, with lithium-ion batteries capped at 100 watt-hours. Recalled, damaged, or defective batteries are barred because they can pose a fire hazard. (southwest.com) The common rule in both cases is isolation. A home backup system needs a switch or other setup that keeps private power from feeding the grid, and an aircraft cabin needs batteries where passengers and crew can see heat, smoke, or swelling quickly. (cucgov.org) (faa.gov) In the Northern Mariana Islands, that warning arrived as the utility posted multiple typhoon-related advisories on April 12. In the air, the Federal Aviation Administration’s guidance has pushed airlines to rewrite carry-on battery rules around visibility and access. (cucgov.org 1) (cucgov.org 2) (faa.gov)
