Top 4th of July Sales Best 4K Projectors 7 Early Prime Day Deals Wi-Fi Range Extenders My Favorite Summer Gadgets Cheap Car Insurance Target's 4th of July Sale Best Running Earbuds, Headphones

The scoop on new air travel battery rules

The "two battery" rule for carry-on luggage applies only to "large" batteries, and there's no federal limit on typical camera, cell phone, toy, and notebook batteries.

On December 28, an Associated Press story was making the rounds that said in part:

To help reduce the risk of fires, air travelers will no longer be able to pack loose lithium batteries in checked luggage beginning January 1, the Transportation Department said Friday.

Passengers can still check baggage with lithium batteries, if they are installed in electronic devices, such as cameras, cell phones, and laptop computers. If packed in plastic bags, batteries may be in carry-on baggage. The limit is two batteries per passenger.

This caused me to perk up at my computer. After all, I routinely travel with at least three spare rechargeable lithium ion batteries (one for my computer, one for my Treo, one for my digital camera) and often more. On some trips, I might also carry various spare nonrechargeable lithium metal batteries for various gear. The checked-luggage thing was no big deal, but if I were truly limited to two spare batteries in my carry-on luggage, that would have been an issue.

The story kicked up the predictable firestorm, only somewhat muted by its appearance over the holidays. Fortunately, it turns out to be incomplete on a critical point. You can find more detailed background and analysis elsewhere, but I thought that it would be useful to reiterate a few critical points, given the incorrect information floating around (and the fact that the Department of Transportation Web page that "explains" the rule is written in rather confusing government speak).

  • Loose (i.e., those not installed in equipment) lithium and lithium ion batteries may, in fact, no longer be put into checked luggage.
  • The "two-battery limit" applies only to lithium ion batteries with more than "8 grams of equivalent lithium content, (which) is approximately 100 watt-hours." The Reader's Digest version is that this limit roughly corresponds to the largest notebook batteries.

    In other words, this limit shouldn't much affect most travelers because there's no limit on typical camera, cell phone, toy, and notebook batteries. So what is affected? Things like external notebook and professional videographer batteries. (I suspect that independent videographers will be one of the groups this new rule could inconvenience.)

  • One issue is that implementing the rule in the field is basically impossible, unless the screeners are just given some rule of thumb like "no limit on notebook batteries or anything smaller."

    My notebook battery is marked only with a voltage and a milliAmp (current) rating. One can convert this to grams of equivalent lithium content (0.3 x voltage x Ah), but somehow, I don't see the screeners at security scrutinizing the label rating of batteries (when present) and whipping out calculators. So we'll have to see how notebook batteries in particular end up being counted, though I don't really expect issues around smaller camera and cell phone batteries.

  • There is no limit on batteries below the 100 watt-hour limit in carry-on luggage.
  • The other relevant part of the rule is that loose batteries are now supposed to be placed in individual plastic bags or otherwise stored in a way that their contacts can't be shorted out. It's impossible to say to what degree this will be enforced, but it's probably something else to put on your travel prep list.

Finally, I think it's worth noting that--much fevered commentary aside--this is not some new inane security rule. It's a response to lithium batteries being suspected as the cause in at least one cargo plane fire. Laptops have also burst into flames rather dramatically because of battery problems. Thus, lithium and lithium ion batteries are known to be problematic from a safety perspective.

However, it's also the case that the mobile-information age essentially runs on these batteries, and any outright ban would be incredibly disruptive. The trick, as always, is therefore to strike a reasonable balance between safety and convenience. These new rules seems to do that--at least on paper.