It’s not uncommon for a laptop user to tote along an extra battery or two for those long flights, especially with the possibility of in-flight internet access coming soon. Starting January 1, 2008 the U.S. Department of Transportation will start placing restrictions on the number and size of lithium batteries that can be brought along on a U.S. flight giving you one more thing to remember before boarding a plane.

Lithium batteries are a very common type of battery used in many kinds of portable electronic devices such as digital cameras, media players and notebook computers. The new restriction will not affect batteries that are installed in their intended electronic devices, but only spare batteries that are brought along. Loose, spare batteries will no longer be allowed to be placed in checked luggage, and any spare batteries that are carried on must be in the original packaging or placed in a plastic bag to prevent contacting metal parts and the possibility of a resulting fire.

The new restriction also limits the number and size of extra batteries that can be carried onto a U.S. flight. Batteries that contain 8 grams or less of lithium are considered acceptable and there is no restriction on the number of spare batteries that can be carried on. Most devices including laptops use batteries with less than 8 grams of lithium. Batteries that have more than 25 grams of lithium in them will not be allowed, and the combined weight of all batteries that contain more than 8 grams of lithium cannot exceed 25 grams total.

If this all sounds confusing, from now on just be sure to carry on any spare batteries and make sure that they are not excessively large. And hopefully by now you’re already used to checking all of you liquids greater than 3 ounces. The new restriction was imposed because the Federal Aviation Administration found that the fire protection systems on flights could not dowse fires created by the lithium batteries, and the National Transportation Safety Board could not rule out a lithium battery as the cause of a cargo plane fire in Philadelphia in 2006.

via NYT