Using Old android Phone As an RTC o NTP

hi
i have created an automation project couple of years ago using single Arduino board and single 16 channel relay board it will do the watering for about 200 trees and it will fill up a huge tank in a farm at a remote location where no internet is available and even power is not that stable
scheduling without RTC is not nice especially when power is not stable i have tried a couple of RTC different shapes and sizes ..it will work for couple of weeks but then they start Drifting
i have mitigated this issue by installing hardware timer that will turn on the Arduino on daily basis the problem with this setup is i have some tasks need to run on daily bases and others every other day ...etc
the hardware timer cannot handle that much schedule !

now having real time clock is became a MUST and i don't want to try RTC chips anymore...ever
is there a way to use an old android phones (since i have more than 5) as an NTP or RTC with Arduino ?
any idea or help will be appreciated