I'm back! Did ya miss me? Hey, thanks. Let's start off your '08 with some good old-fashioned news about air travel, a big mess of new rules that are sure to confuse and entertain you all year. This time, the FAA has taken aim at lithium batteries, a response to the bevy of exploding laptops that menaced offices and airports alike over the last two years (one of which occured at LAX).

The new rules are confusing and extensive (and are being reported incorrectly in numerous mainstream publications), so I'll try to boil it down for you here, accurately. Hit the link at the end of the story for the entire text of the new rules straight from the horse's mouth. The rules took effect on Jan. 1, 2008.

• Installed batteries (already in your phone, laptop, camera, etc.) and spare batteries (carried loose) are treated differently. Only lithium-based batteries are concerned here, not nickel-based rechargeables or alkaline batteries.
• You can't pack spare batteries in checked baggage...but you may check equipment with batteries installed.
• In your carry-on baggage, you can take as many batteries along as you want (installed or spare), as long as they contain less than 8 grams of lithium content each. How do you know how much lithium is in a battery? An 8-gram battery equals about 100 watt-hours of power. Now, your battery won't say how many watt-hours it provides, but it's easy to do the math. Look on the bottom and you'll find a voltage rating and a mAh (milliamp-hours) rating. Multiply these two together and divide by 1,000. That's your watt-hours. In the (big) battery I'm looking at as an example, it offers 11.1 volts and 7,800 mAh. Multiply and divide by 1,000 and you get 86.58 watt-hours, acceptable under the new rules.
• Now, you can also bring two spare batteries that break the above rule. These two batteries can have a total lithium content of 25 grams, or about 300 watt-hours. Where might you find such a giant battery? Namely in those third-party laptop battery slabs designed to give you a full day of computing. A product like this Electrovaya PowerPad 300 would just barely make it... but would probably earn you a delay at security.
• These rules mainly concern lithium-ion batteries. Lithium metal batteries (which are comparably rare) have more stringent rules. Check the link for full details if you use lithium metal batteries, but since lithium metal batteries are usually quite small, there's not that much cause for concern.

Whew! Bottom line: Most travelers are fine as they are now, especially if they don't bring along spare batteries. If you do carry spares, take a look at the FAA's safety tips, which advise placing spare cells in a plastic bag to prevent short circuits. Just make sure those spares aren't too big, and only carry two.

LINK: FAA Battery Rules 2008