The DS3231 is a low-cost, extremely accurate I2C real-time clock (RTC) with an integrated temperature-compensated crystal oscillator (TCXO) and crystal.
A real-time clock (RTC) is a computer clock (most often in the form of an integrated circuit) that keeps track of the current time.
It integrated with a battery input, which can maintain accurate timekeeping when power off. The integrated crystal resonator ensures the accuracy of clock. So this RTC solution should be worth to try.
This module should be used together with EASY plug control board.