I had one tag on my greenhouse during summer. Suddenly it stopped, and i checked and battery was dead (1.5V), battery was used around 6 months. I changed battery and after 1 month (inside my house), same happened again). something is draining battery very fast suddenly.
If the unit has been in humid environment for long times, it’s always possible that condensed water may have damaged electronics one way or another.
You could try to clean the PCB if you can see visible damages on it.
This topic is related and I can see that you already commented on it:
It seems so. I tried to clean pcb (as we have in our office rework station). it remains to see whether it helps. Some impurities were visible. Now I am checking whether humi sensor is operating, since after cleaning of PCB it showed long time 100%.
No, no help, seems that hum sensor is permanently off (in same place other sensors are showing around 53-54% of hum, and this broken one 83%… ) temp and pressure are ok.
It seems that cleaning helped eventually. Battery voltage is holding much higher than before. Also hum values are very close to other sensors, so hum sensor is alive also.
I have had this issue from use in a cell culture incubator. In my case you could see the evidence of electrolytic corrosion. Still, I suspect the reasons for complete foobing of the device are different than only a dead battery. In a high humidity environment, even without condensation there will be a layer of adsorbed water through which leakage current can flow. That will drain the battery. If that leakage path is particularly low resistance it can result in battery voltages going to places they shouldn’t be, such as sensitive inputs on the ICs. That can foob the whole thing, as was the case for one of my tags. By watching the voltage reading intently, one could probably monitor the leakage and keep the foobing from happening. Just my 4 cents. Cheers.