[Zak]

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

[layer8]

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.

[Hnrobert42]

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.

[tinus_hn]

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

[atoav]

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?

[someweirdperson]

> use passive components (discharging capacitors)

mechanical egg timer?

[llampx]

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

[atoav]

Candle clock