eli5 why phones drain battery even when they are turned off?
In: Technology
All batteries self discharge, all of them, everyone single one including the ones in phones
A battery is two reactive chemicals that want to react with each other, held in separate compartments separated by a barrier. When the device needs power, it’s like opening a little path from one compartment to the other that lets some of the chemicals react with each other and the reaction produces electricity.
No compartment or barrier is 100% atomically leak-proof, so over time *every* battery will slowly discharge itself. Phone batteries, AA/AAA batteries, car batteries, they all discharge themselves over time. Even if the batteries aren’t in a device at all! You can buy batteries, leave them in the sealed packaging, and in a few years they’ll be dead due to all the chemicals inside reacting. This proves that this slow drain isn’t coming from the turned-off device still using some power, it’s just the battery leaking and discharging on its own.
**TLDR:** It’s not that the phone is using a bit of power even when it’s off. The phone is using 0 power but **every battery leaks**, at least a little.
As others have pointed out, batteries discharge by themselves over time, but the other side of the story is that a phone is never turned entirely off; most of the circuitry is put in a dormant state, but there is still a tiny part that monitors the off-on button.
In fact, this applies to a lot of electronics in general.
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