After 10 years using cheap DS3231 modules I finally got serious about synchronizing the logger clocks for group deployments. Primarily this is to improve data quality for things like tide signal analysis, but also to address the increasing number of DS3231-M chips we’ve been getting lately that aren’t up to snuff. In addition to synchronizing the time setting process to the leading edge of a GPS pulse, we also (taking a lead from HeyPete and others) tune the Aging register to reduce clock drift. The quid pro quo is that the reduced drift within the tuning temperature range increases non-linearity at more extreme temperatures. But underwater/cave research sites are quite thermally stable compared to outdoor climate stations, so it’s worth that tradeoff.

For all the gory details see the blog at:
https://thecavepearlproject.org/2024/10/22/setting-accurate-rtc-time-with-a-gps-the-ds3231-aging-offset-to-reduce-drift/