@fifo Well done! - probably the new module needed a little extra power and the power brick was already failing so this pushed it over the edge. Failing psu can be difficult to diagnose until they fail completely, especially if encapsulated.
Power supply and cabling are usual suspects in this type of work.
Well done and good luck with the rest of the project!
Thank you for your answer
I'm trying to compare with only pro mini and rfm69 on a test plate, and 2 AA batteries. I have strange result, and i'm doubting about my multimeter.
I'll continue testing and will tell you
The graph above is from my oldest window contact that is still in service with its first CR2032. It has reported 2902 events in over a year (less than 8 wake cycles per day on average).
The second graph is from my oldest temperature & humidity node, also running off a CR2032. Since march 2020, it reported 180k data points (temp & hum every 5 minutes).
Unfortunately I didn't configure them to report the battery voltage back then, but I took a reading with my DMM right now: The window node reads 3.041V and the temperature node 2.993V. What I'm trying to show is that nodes can run for years with a CR2032.
The temperature node should be the most discharged CR2032 I have in use currently, so I have yet to find out at which voltage they stop working. But I think 2.8V should still be fine if you have enough capacity to counteract the voltage drop during transmission.
If the battery in your node died suddenly, I guess the node may have failed to sleep for some reason. I had this issue before a couple of times and I can only assume that the node lost connection to the repeater and drained the whole battery in a find-parent-loop.
I have been doing exactly this recently. Though my CO2 sensor was 3.3V. But a solution could be powering the sensor with the VIN 5v pin and using a level shifter for communication. That's what I did with the 5V screen I used (though I didn't need a level shifter). I also added a lithium battery with a charging and safety circuit hooked up to a boost converter making it 5V and connected that with VIN and GND.