If you're one of the millions of airline travelers who carry spare lithium laptop, cell phone and camera batteries with you, listen up: The government has some new rules which go into effect on New Year's Day.

Fortunately, the Transportation Security Administration (TSA) is

not

worried about the batteries installed in your devices, be it an iPhone or laptop. Those are safe to bring along with you on the plane in your carry-on bag.

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But the TSA is worried about loose, spare batteries. These are batteries with uncovered electrical contacts, which, if touched by other metal objects could cause an explosion and fire during a flight. So, the agency wants to make sure that any spare lithium batteries you take with you on your flight meet its new standards.

Simply speaking, the rules are that you can't pack spare lithium batteries in your checked luggage and can bring spare batteries with you in your carry-on luggage -- up to a point.

Look a little further and you find things get somewhat tricky.

As for exactly what you're allowed to bring onto the plane, it all has to do with the actual amount of lithium contained in the each battery. According to the new government rules:

The new lithium quantity limits apply to both your spare and installed batteries. The limits are expressed in grams of "equivalent lithium content." Eight grams of equivalent lithium content is approximately 100 watt-hours; 25 grams is approximately 300 watt-hours.

Under the new rules, you can bring batteries with up to 8 grams of equivalent lithium content. Most lithium ion batteries in cell phones and laptop computers are below this quantity threshold.

You can also bring up to two batteries with an aggregate equivalent lithium content of up to 25 grams, in addition to any batteries that fall below the 8-gram threshold.

For a lithium metal battery, whether installed in a device or carried as a spare, the limit on lithium content is 2 grams per battery.

The bottom line for travelers is most consumer-type lithium batteries are permitted. Very large, professional batteries are a different story. If you are unsure, contact the device's manufacturer before you pack your bags and leave for the airport.

For more information, and some helpful photos, you can read

the official announcement on the U.S. Department of Transportation's SafeTravel Web site.

Good luck.

With 34 years experience as a journalist -- the last 27 with

NBC

-- Gary Krakow has seen all the best and worst technology that's come along. Gary joined MSNBC.com before it actually went online in July 1996. He produced and anchored the first live Webcast of a presidential election in November 1996. With a background as a gadget freak, audiophile and ham radio operator, Krakow started writing reviews for both Audio and Stereophile Magazines in the 80s. Once at MSNBC.com, Krakow started writing a column to help feed his personal passion for playing with gadgets of all types, shapes and sizes. Within a short time, that column became a major force in many electronics industries -- audio, video, photography, GPS and cell phones. Readership soared, and manufacturers told him they had actual proof that a positive review in his column sold thousands of their products. Many electronics manufacturers have used quotes from his reviews in their sales literature as well as on their Web sites. There have also been a few awards too, including Emmys in the 70s, 80s and 90s.