How does tech keep time when shut off?

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How can my phone with no cell service or wifi be shut off and turned back on to tell the correct time and date? Does my phone use battery while “dead” to keep some functions running?

In: Technology

5 Answers

Anonymous 0 Comments

Old motherboards had essentially a watch battery inside them that would keep the timekeeping circuit powered; for most clocks, the most power draw is the display and the circuitry for figuring that out (or for an analog clock, the motors rotating the gears to make the hands turn), so a chip whose only job is to keep track of time is pretty low-powered.

Haven’t checked a phone, but it is likely that it keeps some of the battery reserved for that, or runs updates in the background; often even if there’s not enough cell service for a call or text, there’s enough cell service to correct your time. There’s also the time that the GPS will give the phone, though because of relativity those clocks aren’t exactly right. Basically lots of ways for a phone to save/get the time without you knowing.

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