No, Lufthansa Isn’t Banning AirTags from Luggage

jcenters · October 12, 2022, 10:33pm

Originally published at: No, Lufthansa Isn’t Banning AirTags from Luggage - TidBITS

German airline Lufthansa set off a firestorm when it claimed that AirTags aren’t allowed in checked baggage, but it was a simple case of confusion about regulations.

Shamino · October 12, 2022, 11:01pm

Nit pick: The CR2032 battery used by AirTags is a 3V lithium cell, not alkaline.

According to this page, the first letter of a coin cell type indicates its chemistry. (The “R” means “round”, with the numbers indicating diameter and thickness. The most common type is “C” (e.g. CR2032), which uses Lithium Manganese Dioxide (LiMn0₂). Less commonly, you may find “B” (e.g. BR2032), which is Lithium/Carbon Monofluoride Li-(CF)x.

Type “B” cells have a much longer shelf life and are therefore often used for devices like clocks, which draw very small amounts of current for a very long time.

Both type “C” and type “B” are disposable batteries and (as far as I know) can not be recharged, so they shouldn’t trigger any rechargeable battery laws. And they definitely do not use the Li-ion chemistry used in phone/tablet/laptop batteries.

(There are other chemistries for the “R2032” size, which are rechargeable, but they are far less common).

jcenters · October 13, 2022, 3:03pm

Thanks, I’ve fixed that now, and I dove down a rabbit hole of battery chemistry. Apparently, the big difference between alkaline and lithium is that the voltage output from alkaline batteries drops over time and lithium stays constant even as the battery is drained.

Shamino · October 13, 2022, 4:01pm

Yep. Alkaline (and their predecessor, carbon-zinc, sometimes sold as “long life” or “heavy duty”) batteries have a nominal voltage of 1.5v per cell. It’s slightly higher when new, and it drops off as the cells age. (A so-called “9v” battery actually has 6 cells packed inside the enclosure).

Most lithium batteries have a nominal voltage of 3v per cell (with some being 3.6v), and it tends to remain steady until they die, and then suddenly drop to near-zero.

One interesting variant is the Lithium iron disulfide (LiFeS₂) battery, which has an open-circuit voltage of 1.8v, but drops to levels compatible with alkaline batteries when used in-circuit. These are what you find in lithium AA cells. They are preferred for cameras since they can handle sudden bursts of high current, like you get from an old style (non-LED) flash. See also AA battery - Wikipedia

dougeddy · October 13, 2022, 4:03pm

Thank you both. This information was great and I learned a lot!

Ratsima · October 15, 2022, 10:32pm

I’ve got some bluetooth temperature/humidity sensors that use R2032 batteries. I find that the CRs last about 6 months with bluetooth polling (from a Mac) done hourly. Would BRs be appropriate for these devices and offer a longer life? I note that the BRs are much more expensive and harder to find than the CRs.

hschlickenmaier · October 16, 2022, 2:32am

One minor nitpick on a great article!

The International Civil Aviation Organization is “ICAO” not “ICAC” – I’ve worked with them for several decades, and I got a minor case of cognitive whiplash!

Thanks for all of your great articles!

Shamino · October 17, 2022, 1:20pm

Good question. BRs have a slightly lower nominal voltage, but a higher cut-off voltage. They have a longer shelf-life, but I don’t know how this will translate to lifespan for a device that is active for an extended period of time (as is the case for your sensors).

it might be interesting to give it a try, but as you say, BRs are more expensive.