With new TSA rules on laptops and cellphones, keep chargers handy

How many times have you boarded a flight with a dead cellphone or laptop?

Under new TSA rules, if you do so when returning to the U.S. from abroad, you’d better keep your charger or mobile battery pack in your carry-on bag — or risk having your electronic devices confiscated.

Travelers on direct flights to the U.S. from some overseas airports (which ones aren’t specified) must be able to power up devices when they go through airport security. “Powerless devices will not be permitted onboard the aircraft,” the Transportation Security Administration announced in a release Sunday. “The traveler may also undergo additional screening.”

Why? U.S. officials fear that Middle East terrorists have developed a way to hide explosives from metal detectors, body scanners and pat-downs.

Here are some tips to keep in mind if you’re flying home from an overseas trip:

—Charge your devices before you go to the airport.
—Keep chargers in your carry-on luggage, not in checked bags.
—You might want to carry extra battery packs, and not the kind you put in your phone.

External batteries, or juice packs, act as miniature power chargers when you can’t find a place to plug in. The Mophie powerstation XL ($129), for example, quickly charges two tablets at the same time, and Mophie’s power reserve ($49) charges iPods and iPhones.

Jackery makes a lightweight mini portable charger ($19.95) that works with Apple products (iPhones, iPad, Air, Mini), Samsung Galaxy phones and other devices.

If you need help sorting this out, CNET and PCWorld offer good product comparisons and tips on how to choose a mobile charger.

And one last bit of advice: Carry extra cables. Nothing sadder than having a battery pack with no way to connect to your devices.