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Comment by smoldesu | Hacker News Reader

The more predominant issue is keeping anything with a lithium-ion battery in checked luggage. They'll crack down on anything from laptops to hearing aids.

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CR2032 batteries that are in airtags are NOT lithium-ion, they're non-rechargeable and are usually Lithium/Manganese Dioxide [1] (lithium metal). I believe they're fine to have in checked luggage if contained inside some equipment (like the airtag). [2] Look for PI 970 If transported by themselves, they're cargo aircraft only.

Source: [1] https://data.energizer.com/pdfs/cr2032.pdf [2] https://www.iata.org/contentassets/05e6d8742b0047259bf3a700b...

The wording “containing lithium metal” from the ICAO regulation still applies.

That same org also explicitly calls out button cells are not being covered. They really aren't the same thing as a rechargeable lithium ion cell.

They're fine to have in checked luggage (under some restrictions). But the device containing them must be completely switched off, according to the rules. That is at issue here.

Both lithium-ion and lithium metal batteries that are installed in devices are allowed in checked baggage in the US and most other places. The devices must be powered off. What that means is a bit ambiguous as most modern laptops, tablets, and phones have some components powered any time a battery is installed.

https://www.faa.gov/newsroom/lithium-batteries-baggage

The regulation specifically states that "the devices must be completely switched off (not in sleep or hibernation mode)", and mobile devices normally all have a way to completely shut them down, with no components remaining active. The only exception I'm aware of are wireless earbuds (e.g. AirPods). Presumably you're not allowed to have those in checked baggage.

So electrical engineers could just use a MCU let it power itself of during flight, use passive components (discharging capacitors) to trigger a wakeup after a set time and you are good to go?

> use passive components (discharging capacitors)

mechanical egg timer?

Definitely no problem with a ticking noise coming from your luggage.

Candle clock

I would wager most people don’t realize that to completely turn off their iPhone they must adjust their settings to not use Find My even when powered off.

And to tell it somehow not to keep the clock running. Which of course is not possible.

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