I used minicore bootloader.

I used the small pir sensors and again removed the regulator to power directly from the pro mini outputs.

After that sleep the node and trigger on interrupt.

Send battery level once a day.

Use inbuilt battery level monitor and not external components that constantly drain power to get battery level.

1.8V is 0% on the graph (not visible yet!) but I have had nodes working below 1.7V It's a matter of luck with that it seems.

Hope this helps you on the right track. I'll try and help if you want.

This is the latest image and still going strong after 18 months. Voltage is at 2.903V

Here is photo of the test example - I need to make a case and produce more of them over winter.....

Here is the same build/code of a window sensor. Similar time frame but hardly triggered.....

.... All was ok, so what did you change (and why)

A the very beginning, hesitating with the procedure, I've probably burnt the Minicore bootloader in the programming ProMini without noticing it... That's the only explanation I see.

PS: Could the admin delete all my useless posts ?

  // ************Sleeping test ***************
    #ifdef MY_DEBUG 
        delay(10000); // 10 secondes
    #else
        sleep(10000);
    #endif    
}

Delay should be replaced by Wait in mysensors code to avoid blocking.

I always went by the old saying that when you are in a hole, stop digging. I have not seen the behaviour you show before. I can only suggest that you run the EEPROMclear sketch (file>examples>mysensors>cleareepromconfig) and try again. Check the voltage to the promini is stable and the radio has the recommended capacitor. You might be surprised at the difference a good clean power supply can make.

#is the gateway running on the same power supply? IS GW receiving messages? Please provide the FULL debug output on the serial monitor. That snippet doesn't help much.

@Gilles-BILLARD I understnad your frustration - I have been there myself.

I suggest s simple node to test with, something like the door/window sensor with just one switch.

I did that right away and the result is....
All's OKay without sleep(xxx):

2021-04-10 17:38:22.898 Status: MySensors: Node: 52, Sketch Name: Temperature Sensor Sleep
2021-04-10 17:38:22.899 Status: MySensors: Node: 52, Sketch Version: GB.3.0
2021-04-10 17:40:25.515 (GiBi-Home) Light/Switch (Security Sensor)
2021-04-10 17:40:31.277 (GiBi-Home) Light/Switch (Security Sensor)

Présentation then 2 minutes until I change the input twice

But with sleep() included...

2021-04-10 17:34:12.251 Status: MySensors: Node: 51, Sketch Name: Temperature Sensor Sleep
2021-04-10 17:34:12.251 Status: MySensors: Node: 51, Sketch Version: GB.3.0
2021-04-10 17:34:22.491 (GiBi-Home) Light/Switch (Security Sensor)
2021-04-10 17:34:22.486 Status: MySensors: Node: 51, Sketch Name: Temperature Sensor Sleep
2021-04-10 17:34:22.486 Status: MySensors: Node: 51, Sketch Version: GB.3.0
2021-04-10 17:34:32.561 (GiBi-Home) Light/Switch (Security Sensor)
2021-04-10 17:34:32.556 Status: MySensors: Node: 51, Sketch Name: Temperature Sensor Sleep
2021-04-10 17:34:32.556 Status: MySensors: Node: 51, Sketch Version: GB.3.0
2021-04-10 17:34:42.631 (GiBi-Home) Light/Switch (Security Sensor)
2021-04-10 17:34:42.626 Status: MySensors: Node: 51, Sketch Name: Temperature Sensor Sleep
2021-04-10 17:34:42.626 Status: MySensors: Node: 51, Sketch Version: GB.3.0
2021-04-10 17:34:52.701 (GiBi-Home) Light/Switch (Security Sensor)
2021-04-10 17:34:52.696 Status: MySensors: Node: 51, Sketch Name: Temperature Sensor Sleep
2021-04-10 17:34:52.696 Status: MySensors: Node: 51, Sketch Version: GB.3.0
2021-04-10 17:35:02.772 (GiBi-Home) Light/Switch (Security Sensor)
2021-04-10 17:35:02.767 Status: MySensors: Node: 51, Sketch Name: Temperature Sensor Sleep
2021-04-10 17:35:02.767 Status: MySensors: Node: 51, Sketch Version: GB.3.0
2021-04-10 17:35:12.842 (GiBi-Home) Light/Switch (Security Sensor)
2021-04-10 17:35:12.837 Status: MySensors: Node: 51, Sketch Name: Temperature Sensor Sleep
2021-04-10 17:35:12.837 Status: MySensors: Node: 51, Sketch Version: GB.3.0
2021-04-10 17:35:22.913 (GiBi-Home) Light/Switch (Security Sensor)
2021-04-10 17:35:22.908 Status: MySensors: Node: 51, Sketch Name: Temperature Sensor Sleep
2021-04-10 17:35:22.908 Status: MySensors: Node: 51, Sketch Version: GB.3.0
2021-04-10 17:35:32.984 (GiBi-Home) Light/Switch (Security Sensor)
2021-04-10 17:35:32.979 Status: MySensors: Node: 51, Sketch Name: Temperature Sensor Sleep
2021-04-10 17:35:32.980 Status: MySensors: Node: 51, Sketch Version: GB.3.0
2021-04-10 17:35:43.055 (GiBi-Home) Light/Switch (Security Sensor)

The same kind of reboot up to présentation()

So sad !
NOTA: The sketch is the one provided as an example in BinarySwitchSensor.ino sketch
I've just added sleep( 10000) a the very end.

...........have you checked the baud rate the pro mini or uno you are using as a programmer - maybe it is 115200 and that is optimistic for a 3.3V board.

The programmer is loaded with standard Arduino ISP sketch (19200 default baud rate)

@Gilles-BILLARD It's in the sketch when you start serial interface. As an aside have you checked the baud rate the pro mini or uno you are using as a programmer - maybe it is 115200 and that is optimistic for a 3.3V board. Make sure the programmer is using 19200 just to be safe.

For inof I am using arduino ide 1.8.13 and musensors 2.3.2 with a £2 aliexpress serial prgrammer and have only encountered warnings about sck (which can safely be ignored)....

Ha, OKay; I've aslo supposed a pb from that, so I removed the sérial monitor and baud rate config.
And after the bootlaoder burning, the log is OKay.. the MEGA328P ID is also the good one and always the same for all 328

Bought from Aliexpress;

That is not much help.

For inof I am using arduino ide 1.8.13 and musensors 2.3.2 with a £2 aliexpress serial prgrammer and have only encountered warnings about sck (which can safely be ignored)....

I suggest s simple node to test with, something like the door/window sensor with just one switch.

I'll do that, but for my thermal sensor the test cannot be more simple

......burn MiniCore bootloader with 9600 baud, 3.3V, 8MHz INTERNAL, BoD DISABLED.

I don't have the choice for the baud rate; Where is it located ?

Then add the radio module (you can try another if you have it

I swaped everything I could. (The radio modules that was connected to the single functionning sensor included)

what radio modules are you using? - A link or photo might help, there are bad ones and fakes that could be a problem for you).

Bought from Aliexpress;

Load your sketch and try again.

I have done the whole process hundreds and hundreds of time

You can measure the current to the whole set up and then just the radio to see if radio is not sleeping. ....

Yes I'll do that...

I suggest s simple node to test with, something like the door/window sensor with just one switch.

Take your promini, remove leds and power regulator (or cut tracks) then burn MiniCore bootloader with 9600 baud, 3.3V, 8MHz INTERNAL, BoD DISABLED.

Then add the radio module (you can try another if you have it - what radio modules are you using? - A link or photo might help, there are bad ones and fakes that could be a problem for you). Load your sketch and try again.

You can measure the current to the whole set up and then just the radio to see if radio is not sleeping. ....

C:\Users\billa\AppData\Local\Arduino15\packages\MiniCore\hardware\avr\2.1.1\bootloaders\optiboot_flash\bootloaders\atmega328p\8000000L

avrdude: Version 6.3-20201216
         Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
         Copyright (c) 2007-2014 Joerg Wunsch

         System wide configuration file is "C:\Users\billa\AppData\Local\Arduino15\packages\MiniCore\hardware\avr\2.1.1/avrdude.conf"

         Using Port                    : COM8
         Using Programmer              : stk500v1
         Overriding Baud Rate          : 19200
         AVR Part                      : ATmega328P
         Chip Erase delay              : 9000 us
         PAGEL                         : PD7
         BS2                           : PC2
         RESET disposition             : dedicated
         RETRY pulse                   : SCK
         serial program mode           : yes
         parallel program mode         : yes
         Timeout                       : 200
         StabDelay                     : 100
         CmdexeDelay                   : 25
         SyncLoops                     : 32
         ByteDelay                     : 0
         PollIndex                     : 3
         PollValue                     : 0x53
         Memory Detail                 :

                                  Block Poll               Page                       Polled
           Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
           ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
           eeprom        65    20     4    0 no       1024    4      0  3600  3600 0xff 0xff
           flash         65     6   128    0 yes     32768  128    256  4500  4500 0xff 0xff
           lfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           hfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           efuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           lock           0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           calibration    0     0     0    0 no          1    0      0     0     0 0x00 0x00
           signature      0     0     0    0 no          3    0      0     0     0 0x00 0x00

         Programmer Type : STK500
         Description     : Atmel STK500 Version 1.x firmware
         Hardware Version: 2
         Firmware Version: 1.18
         Topcard         : Unknown
         Vtarget         : 0.0 V
         Varef           : 0.0 V
         Oscillator      : Off
         SCK period      : 0.1 us

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.04s

avrdude: Device signature = 0x1e950f (probably m328p)
avrdude: erasing chip
avrdude: reading input file "0x3f"
avrdude: writing lock (1 bytes):

Writing | ################################################## | 100% 0.02s

avrdude: 1 bytes of lock written
avrdude: verifying lock memory against 0x3f:
avrdude: load data lock data from input file 0x3f:
avrdude: input file 0x3f contains 1 bytes
avrdude: reading on-chip lock data:

Reading | ################################################## | 100% 0.02s

avrdude: verifying ...
avrdude: 1 bytes of lock verified
avrdude: reading input file "0b11111111"
avrdude: writing efuse (1 bytes):

Writing | ################################################## | 100% 0.02s

avrdude: 1 bytes of efuse written
avrdude: verifying efuse memory against 0b11111111:
avrdude: load data efuse data from input file 0b11111111:
avrdude: input file 0b11111111 contains 1 bytes
avrdude: reading on-chip efuse data:

Reading | ################################################## | 100% 0.02s

avrdude: verifying ...
avrdude: 1 bytes of efuse verified
avrdude: reading input file "0b11011110"
avrdude: writing hfuse (1 bytes):

Writing | ################################################## | 100% 0.02s

avrdude: 1 bytes of hfuse written
avrdude: verifying hfuse memory against 0b11011110:
avrdude: load data hfuse data from input file 0b11011110:
avrdude: input file 0b11011110 contains 1 bytes
avrdude: reading on-chip hfuse data:

Reading | ################################################## | 100% 0.02s

avrdude: verifying ...
avrdude: 1 bytes of hfuse verified
avrdude: reading input file "0xe2"
avrdude: writing lfuse (1 bytes):

Writing | ################################################## | 100% 0.02s

avrdude: 1 bytes of lfuse written
avrdude: verifying lfuse memory against 0xe2:
avrdude: load data lfuse data from input file 0xe2:
avrdude: input file 0xe2 contains 1 bytes
avrdude: reading on-chip lfuse data:

Reading | ################################################## | 100% 0.01s

avrdude: verifying ...
avrdude: 1 bytes of lfuse verified

avrdude done.  Thank you.


avrdude: Version 6.3-20201216
         Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
         Copyright (c) 2007-2014 Joerg Wunsch

         System wide configuration file is "C:\Users\billa\AppData\Local\Arduino15\packages\MiniCore\hardware\avr\2.1.1/avrdude.conf"

         Using Port                    : COM8
         Using Programmer              : stk500v1
         Overriding Baud Rate          : 19200
         AVR Part                      : ATmega328P
         Chip Erase delay              : 9000 us
         PAGEL                         : PD7
         BS2                           : PC2
         RESET disposition             : dedicated
         RETRY pulse                   : SCK
         serial program mode           : yes
         parallel program mode         : yes
         Timeout                       : 200
         StabDelay                     : 100
         CmdexeDelay                   : 25
         SyncLoops                     : 32
         ByteDelay                     : 0
         PollIndex                     : 3
         PollValue                     : 0x53
         Memory Detail                 :

                                  Block Poll               Page                       Polled
           Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
           ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
           eeprom        65    20     4    0 no       1024    4      0  3600  3600 0xff 0xff
           flash         65     6   128    0 yes     32768  128    256  4500  4500 0xff 0xff
           lfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           hfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           efuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           lock           0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           calibration    0     0     0    0 no          1    0      0     0     0 0x00 0x00
           signature      0     0     0    0 no          3    0      0     0     0 0x00 0x00

         Programmer Type : STK500
         Description     : Atmel STK500 Version 1.x firmware
         Hardware Version: 2
         Firmware Version: 1.18
         Topcard         : Unknown
         Vtarget         : 0.0 V
         Varef           : 0.0 V
         Oscillator      : Off
         SCK period      : 0.1 us

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.05s

avrdude: Device signature = 0x1e950f (probably m328p)
avrdude: NOTE: "flash" memory has been specified, an erase cycle will be performed
         To disable this feature, specify the -D option.
avrdude: erasing chip
avrdude: reading input file "C:\Users\billa\AppData\Local\Arduino15\packages\MiniCore\hardware\avr\2.1.1/bootloaders/optiboot_flash/bootloaders/atmega328p/8000000L/optiboot_flash_atmega328p_UART0_38400_8000000L_B5.hex"
avrdude: writing flash (32768 bytes):

Writing | ################################################## | 100% 0.00s

avrdude: 32768 bytes of flash written
avrdude: verifying flash memory against C:\Users\billa\AppData\Local\Arduino15\packages\MiniCore\hardware\avr\2.1.1/bootloaders/optiboot_flash/bootloaders/atmega328p/8000000L/optiboot_flash_atmega328p_UART0_38400_8000000L_B5.hex:
avrdude: load data flash data from input file C:\Users\billa\AppData\Local\Arduino15\packages\MiniCore\hardware\avr\2.1.1/bootloaders/optiboot_flash/bootloaders/atmega328p/8000000L/optiboot_flash_atmega328p_UART0_38400_8000000L_B5.hex:
avrdude: input file C:\Users\billa\AppData\Local\Arduino15\packages\MiniCore\hardware\avr\2.1.1/bootloaders/optiboot_flash/bootloaders/atmega328p/8000000L/optiboot_flash_atmega328p_UART0_38400_8000000L_B5.hex contains 32768 bytes
avrdude: reading on-chip flash data:

Reading | ################################################## | 100% 0.00s

avrdude: verifying ...
avrdude: 32768 bytes of flash verified
avrdude: reading input file "0x0f"
avrdude: writing lock (1 bytes):

Writing | ################################################## | 100% 0.05s

avrdude: 1 bytes of lock written
avrdude: verifying lock memory against 0x0f:
avrdude: load data lock data from input file 0x0f:
avrdude: input file 0x0f contains 1 bytes
avrdude: reading on-chip lock data:

Reading | ################################################## | 100% 0.02s

avrdude: verifying ...
avrdude: 1 bytes of lock verified

avrdude done.  Thank you.

skywatch: You remembered to connect the nrf before going to sleep?
@skywatch Yes, of course;
I'm 67, retired, and after 9 days (part time) on this issue, I give up !
I am therefore torn between crushing all that stuff between between a big hammer and my anvil or to discard everything to the trash can.
These sensors are useless if consuming 20mA H24-7/7 because they they should normally be used outside (in my greenhouses) powered by a battery 18650 + a solar cell.

....... Two blinks for Minicore and one blink for AVR.....>

Thay is not my case; 1 blink for AVR and NO BLINK for MiniCore !?!?!?

avrdude: Version 6.3-20201216
         Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
         Copyright (c) 2007-2014 Joerg Wunsch

         System wide configuration file is "C:\Users\billa\AppData\Local\Arduino15\packages\MiniCore\hardware\avr\2.1.1/avrdude.conf"

         Using Port                    : usb
         Using Programmer              : usbasp
avrdude: error: could not find USB device with vid=0x16c0 pid=0x5dc vendor='www.fischl.de' product='USBasp'

avrdude done.  Thank you

That is the reason why I used or Po-Mini Or UNO as ISP.
I tried to change and test many others drivers for my FTDI (for 2 days) unsuccessfully

are you using FOTA? Is this connected when bootloading the chip? As you can see on one picture, in the programming section, NRF is NOT wired to the programmed Pro-Mini.
Neither it was when I tried to reprogram the wired Pro-mini because I was using the NRF socket to acces the Arduino pins.

.....or installation of arduino IDE/libraries I checked that as well and installed the new Adruino IDE 2.0.0 beta.... same problèms :-//

I just tested a 3V pro mini and was able to to back and forth freely between MiniCore and AVR bootloaders without issue. Two blinks for Minicore and one blink for AVR.

A USB programmer is usually cheaper than an uno, so why not try one and see. That is what I use and the only difference is less cabling and only one arduino in the mix.

In one photo you show nrf24 - are you using FOTA? Is this connected when bootloading the chip?

The error you described a week ago about optiboot should not happen and you should not need to change anything. Try reinstalling the MiniCore library again following the instructions to the letter. Have you in any way modified your boards.txt or changed your arduino ide from default settings or installation path in any way?