FWIW, in the past I’ve had a few times where the DS1307 clock on the Adafruit shield would reset to some random time in the past or sometimes even in the future. If I remember right, I think it usually happened whenever I was trying something new with the hardware, so I just assumed it was sensitive to shorts or other weird electrical gremlins. It has only happened a few rare times with the DS3231 on the Stalker in the past couple years. I stopped using the Adafruit shield for deployments where timing really mattered because the DS13007 is so inaccurate at either high or low temperatures that our timestamps would get horribly fast or slow during the either the winters or summers. But if you’ve got a GPRS unit on the logger, you could just grab the time from a time server occasionally and resync your clock every few weeks.