Adafruit PiRTC - Precise DS3231 Real Time Clock for Raspberry Pi _MAKE_DISPLAY_OLED The Cam Case design provides

The Cam Case design provides space for battery upgrades for those wanting extra juice to power your kit for even longer

The Arduino Ethernet2 library works great

It’s a "re-clocker"

Comes with development resources

The version we have is the 5V Power / 3V Logic

Adafruit PiRTC - Precise DS3231 Real Time Clock for Raspberry Pi _MAKE_DISPLAY_OLED The Cam Case design providesThis is the best battery backed real time clock (RTC) you can get that allows your Raspberry Pi project to keep track of time if the power is lost. Perfect for data logging, clock building, NTP servers, time stamping, timers and alarms, etc. Equipped with a genuine DS3231 RTC, it works great with the Raspberry Pi and has native kernel support. The datasheet for the DS3231 explains that this part is an "Extremely Accurate IC Integrated RTC TCXO