Packing Tech for a Trip: Chargers, Power Banks and Airline Rules

The heaviest part of a carry-on is often the tangle of chargers, adapters and cables that has built up over years of trips. A little planning can cut that to a single small pouch, and it also helps you avoid the rules that catch travelers out at airport security.

The rules for batteries

Power banks and spare lithium batteries must go in your carry-on bag, never in checked luggage. Airlines restrict them because a damaged lithium battery can catch fire, and a fire in the cabin can be spotted and dealt with. The usual limit is 100 watt-hours per battery without airline approval. Most power banks list their capacity in milliamp-hours instead. To convert, multiply by the voltage (usually 3.7) and divide by 1,000: a 20,000 mAh bank works out to about 74 Wh, comfortably under the limit.

Pack

• One multi-port charger. Chargers made with gallium nitride (sold as "GaN") are much smaller than older bricks at the same power, and a 65-watt model with two or three ports can charge a laptop, phone and earbuds from a single outlet.
• Two cables, not six. If your devices use USB-C, one long and one short cable usually covers everything.
• A plug adapter, not a converter. Phone and laptop chargers are almost always rated for 100 to 240 volts, so abroad they only need an adapter to fit the socket shape. Check the small print on the charger to be sure. Hair dryers and straighteners are the usual exceptions.
• A small tracker in checked bags, so you can see where your suitcase is if it doesn't arrive with you.

Leave at home

• Single-purpose gadgets your phone already replaces, such as a separate GPS, camera or e-reader, unless you really use them.
• Bulky voltage converters, unless you're bringing a high-power appliance.
• Charging bricks that only have one slow USB-A port.

Before you leave

Download maps of your destination for offline use, along with any films, shows and playlists for the journey, since airline and hotel Wi-Fi is often slow or expensive. If your phone supports eSIM, buying a data plan for the destination before departure saves hunting for a SIM card on arrival. For children, noise-limiting headphones designed for kids are worth packing, since many adult headphones can go louder than is recommended for young ears.

A simple test before zipping the bag: lay everything out and ask what each item does that nothing else in the pile can. Anything without an answer can stay home.