Adafruit Add-on kits for Raspberry Pi - Adafruit ADA3386, The Adafruit ADA3386 Real Time Clock for Raspberry Pi is battery-backed and allows your Raspberry Pi project to keep track of time if the power is lost.
This device is perfect for data logging, clock-building, time-stamping, and much more.
Equipped with PCF8523 RTC, it works great with Raspberry Pi boards and has native kernel support.
This board is compatible with the Pi 1, Pi 2, Pi 3, Pi Zero, A+, B+, and Pi 4.
Adafruit ADA3386 Real Time Clock for Raspberry Pi