I'm hoping someone can answer this.
I've followed this guide here.
Everything is connected up and working, the device appears to be running solely from battery, interrupt from alarm is working, and can be set via I2C register writes.
However looking at other posts, it seems to suggest you must supply power to the device via the VCC pin in order to write to registers on the ds3231.
See here for example.
Does anyone know if this is correct? It seems to be working fine in my case with new module I have setup and configured. Previously I followed the above advice and connected the VCC pin to high when wanting to write to it, and powering it down when finished. However with this new module all seems fine with VCC set to ground, as the datasheet suggests it should be when operating from battery.
I suppose it could be that the device is leaching power from the SDA/SCL pins, but I'd be interested to see if anyone has any guidance with how this is expected to work.