If I completely shut down a computer and not use it for months, how can it still tell the time accurately? (given that it isn’t immediately connected to the internet)

Question

If I completely shut down a computer and not use it for months, how can it still tell the time accurately? (given that it isn’t immediately connected to the internet)

In: Technology

Answer 1

Not all computers do this.

I’ve tinkered with a Raspberry Pi 3, and it absolutely always needed to stay powered on or use an Internet service to know the time.

The difference between computers that can keep the time and ones that can’t is a “realtime clock” (RTC) circuit or chip.

An RTC is typically powered by a little coin cell battery. On a PC, this battery is usually also used to retain some of the computer’s basic hardware settings in its BIOS or UEFI.