The recent hubbub about the ban on lithium batteries in checked baggage and restrictions on the number of them allowed in carry-on items has me concerned about overzealous agents confiscating other types of batteries. It seems like it has already started to happen outside the United States.

I live in Mexico and have had two run-ins involving batteries within the past year. Security in Mexico is usually a very civil affair, but a few months ago, I was stopped at security in the Toluca airport and asked if they could examine my bags. They seemed to take issue with a clear plastic bag of AA nickel metal hydride (NiMH) rechargeable batteries that I had in my carry-on for use with my 10-year-old, energy-guzzling digital camera.

They asked me why I needed so many batteries and I explained it to them as best I could in my mediocre Spanish. They told me that I would be allowed only the ones in devices and another four, because batteries could explode from the pressure changes resulting in changing altitude. I did not argue that they would be in the pressurized cabin area; if they did not already understand that, my explaining it would make little difference.

I asked why this was the first I'd heard of this restriction, since I had not been hassled about the same bag of batteries on my flight to Toluca. The guard was kind enough to explain that every airport in Mexico has its own distinct set of regulations for what they will allow through security checkpoints.

I stopped myself before commenting that this seemed ridiculously inconsistent, because inconsistency is universal in Mexico. Instead, I asked how a person was supposed to keep track of the different regulations for the republic's some 130 civil airports. I was informed that supposedly every airport has an office where one can get a listing of disallowed items for all of the country's airports.

I was still skeptical about this regulation, having never heard of batteries being a problem before. I gently suggested my suspicion that someone in security needed some AA batteries, and I asked for proof that they would be destroyed and not just given away to someone for their own personal use. I was told that I could return to the airport and file a form to receive such documentation at a later date. Of course!

Since they would not let me pass with all my batteries, I removed five from the bag of about twelve, and that seemed to satisfy them. They let me board the plane with the remaining seven. The letter of the law is not that important in Mexico, and at least this time, that worked in my favor.

A couple of weeks ago, I flew out of Guadalajara to Panama City. My experience of losing about USD $20 worth of batteries in Toluca led me to pack all my NiMH AA batteries in my suitcase.

At the Guadalajara International Airport, they do not X-ray bags, they check them by hand before you check-in. The attendant checking my bag pulled out my bag of 20+ batteries and asked if I needed all of them. I said yes, as I was not going to simply discard them there at the airport, but I did not go through the whole story about the camera again. She called over a supervisor who explained that I could not have all those batteries in one place. Luckily, I was traveling with my partner, and they said it would be okay if we divided the batteries between us. Apparently, in contrast to the regulations in the Toluca airport, it is not okay to carry batteries, or at least not so many all in one place, in checked luggage either, at least not when flying out of the Guadalajara airport.

I suspect that this is all based on a misinterpretation of the 2004 Office of Aviation Research report that has brought about the recent ban on lithium batteries in checked luggage in the United States. This report found that lithium metal batteries could be easily ignited and the resulting heat could melt plastic casings around the batteries, bringing about the ignition of adjacent batteries and larger fires. Even then, the report notes that the risk of this happening is low. Apparently though, air safety administrations and security personnel around the world are not being educated as to the difference between various types of batteries, like alkaline, nickel metal hydride, and lithium ion.

It doesn't seem like I am the only one to encounter this problem, as another FlyerTalk member notes in his blog.

While the new US guidelines are clear to specify lithium, they are not entirely clear in distinguishing between different types (lithium metal, lithium ion). I fear even the distinction of lithium is not going to mean anything to many of the people working at airport security checkpoints, who are going to take this to simply mean "batteries."

I suspect that travelers in the US are going to end up sacrificing a lot of harmless (yet expensive) batteries before the screening agents are adequately educated on the subject, and I suspect that in many countries like mine, they will never be taught the necessary distinctions.