well today about an hour before my watering schedule went off I went out and yanked power to the beagle and removed ethernet; then 50mins later I plugged the beagle back in leaving ethernet disconnected and the sprinklers turned on right on time.
I’d say the RTC works just fine; my only suggestion is look at replacing the battery with a supercap.. a big supercap should keep time for at least a week and unlike a battery it will handle all temperature extremes and will still be running strong in 10 years.. it wont last the winter w/out power but do you really want to start in spring with a weak battery? A Supercap is also cheaper than a brand name lithium CR battery.
Edit, another tip: add: allow-hotplug eth0 to your /etc/network/interfaces so you dont have to reboot when u plug the network back in 🙂