THE BASICS OF BACKUP BATTERIES.
The guy standing under the plane I was about to board seemed to be hitting something with a wrench. It was a smaller passenger jet, so he just popped a hatch toward the tail and started fiddling, as if he were working on the Dodge Dart in his front yard.
And oddly, that was not my biggest worry.
The flight had been delayed 3 hours and I was down to 3 percent power on my phone. The phone that had my digital boarding pass. The gate agents couldn’t print a paper one, so if my phone died, I would have to leave the line and go to the ticket counter, outside security.
It doesn’t matter what technical miracles the latest smartphone can perform — facial scanning, stunning photography, professional teeth whitening — if the gadget doesn’t have power. Especially on the road, when the phone gets more use and contains all your plans. (Recently, my phone was also my room key at a hotel in Chicago — a great trick until the juice is gone.)
That’s where portable external batteries come in. The features, however, can be confusing, and the ones with more power can be bulky and heavy. Here are a few things to know and consider about external batteries:
The basics: External chargers (or power banks) range from lipstick-size models that give most smartphones almost a full charge, to versions the size of a novel that have multiple ports for multiple gadgets, a built-in flashlight and enough power to recharge that same smartphone five to 10 times. How many charges is dictated by the battery’s power in milliamperes (mAh), as well as the size of the gadget’s battery. An iPhone 7, for instance, has a 1,960 mAh capacity, so theoretically, a 5,000mAh power bank would be able to fully charge your phone 2.5 times (although a few variables reduce this number, including if the phone is running power-sucking apps while being charged).
Charging speed: Batteries that have multiple ports often can charge at different speeds (from 1 amp to 2.4 amps), and will include a chip that senses what kind of gadget is being recharged and picks the fastest, safest rate.
You might lose it: A few countries (most notably China) like to confiscate lithium batteries, particularly larger ones. (The rules about what’s forbidden seem to be arbitrary, ranging from batteries stronger than 5,000 mAh to anything that doesn’t have the powerrating marked.)
Carry-on only: Because of incidents involving lithium batteries catching fire, you can’t put external batteries in checked luggage. The upside is you’ll have backup power on a plane that doesn’t have charging outlets; the downside is your carry-on is that much heavier, an important consideration with air carriers that have stingy limits on the weight of carry-ons.
Changing times: The charging ports typically have been USB, but as USB-C ports become more common, more batteries will have that option, making it possible to charge newer laptops with USB-C connections.
Among the more popular companies are Anker (www.anker.com), RAVPower (www.ravpower.com) and Mophie (www.mophie.com), which specializes in battery cases that protect and charge your smartphone.
If you only need quick power for a phone, the lipstick-size chargers are great for keeping in a purse or bag (remember to recharge it). If you need to keep a phone, a tablet and noisecanceling earbuds alive on a 13-hour flight, go with something stronger.