I have set the DS3231 up using the Adafruit instructions. I have edited /lib/udev/hwclock-set, uninstalled the fake-hwclock & disabled ntp.service.
I have also disabled systemd-timesyncd.service.
I can read & write to the hwclock & set it's time from the web (before disabling ntp.service) & write the hwclock time to the system using sudo hwclock -s. So far, so good. If shutdown the Pi & leave the power connected then restart it maybe even the next day, the Pi takes it's system time from the RTC as expected. HOWEVER, if I leave the Pi unpowered for a couple of hours then restart it, the Pi sets the system time to the last shutdown time & also writes that time to the DS3231. II have tried leaving the power on for several days to ensure that the super capacitor is fully charged but still get the same result
I am rather forced to use this RTC module which only uses the top left hand IO pins because I need access to the RH row to power the Pi from the Official 7" touch screen.
I Googled extensively but cannot come up with a solution to this problem.
