sorry saw my mistake with the Voltage and edit it 2 min before you replied. Its a small pump and its working fine with the connected LiPo (normal LiPo .. so around 3.7 - 4.2V)
Why High? Because I had these MOSFETs Laying around and use one in combination with an DS3231 to power the board, see here: Low Active 2A Switch (and I just copied the design )
I tested everything and it worked fine, but maybe the LED I used for the Pump was slightly on all the time but I didnt see it. (using pumps without Water is not a good idea) And yes maybe I should have tested this part more. Everything else is working
And sorry when its confusing, I am softwaredeveloper so working with code is easy for me, working with "voltages" is more an adventure
But I did a similar pcb for a security door watcher and this also is working, but it didnt have the controlable pump switch. I see my problem now, the Voltage of the Feather is not high enough for the MOSFET to stop... but now I have to find a fix for that
The SQW-PIN of the DS3231 goes to GND when an Alarm is triggered. (you can set 2 Alarms in the DS3231) in this case at full hour and at :30. So when this happens, my Feather turns on.
And if you say something like: yeah there is an enabler pin... yes but this doesnt work so stable with the fona.
So in the end: the data will be send every 30 minutes.