Why do smartphones shut down if they run out of battery?

In order to safeguard both the device and the battery, smartphones shut down when their battery runs out.  Here’s why:

 1.   Protection for lithium-ion batteries * The lithium-ion batteries in modern smartphones can be damaged if their charge drops too low. * The capacity of the battery may be permanently reduced or even rendered unsafe if its voltage falls below a safe threshold.   * To prevent this, the phone’s power management system forces a shutdown before the battery is completely drained.

 2.   **System Stability**

The processor, memory, and storage all require a steady power supply.   * If the voltage drops too much, data corruption, crashes, or unexpected errors could occur.

   * Shutting down cleanly prevents this.

 3.   **Safety Reasons**

   * A lithium-ion battery that is drained too much can overheat, swell, and occasionally catch fire.    * The device's safety is ensured by a controlled shutdown. 4.   **User Experience**

   * The phone saves its state and turns off predictably, instead of suddenly "dying" in the middle of an operation.

   * This lowers the likelihood of data loss or damage to the file system.  In a nutshell, **Your phone does not actually reach "zero" battery; rather, it prematurely shuts down to preserve the device's safety, stability, and healthy battery.  **

 Would you like me to explain *why a phone still has a little power left even after it shuts down*?