I already have a aquarium doser running with ESP8266 NodeMCU Dev. Kit.
The actual time to start each doso is got from the RTC widget.
I already tested that during a device internet disconnection, the exact hour, minute and seconds will be still available on the device for a long time.
My question is: assuming that the device not try to reboot, how long the time calculation will keep ok during an internet fail?
Any experience on this?