I have exactly the same issue and also bought the same Panasonic batteries; also had some Duracell batteries but they have the same lifetime nowadays so maybe it is not the battery?
It also seems that the batteries go from OK to NOK in no time. It goes so quickly that the NEO PIR’s don’t even have time to send a battery low warning. Ieven built a workaround flow for that such that I get a alternative warning that the batteries are probably low.
So yes, If there is anybody who knows whats going on then I would be very much interested
But the battery must be measured under load (more or less the same load as in the sensor), otherwise the result is not very meaningful.
If you measure the batteries without load, they usually still show the necessary voltage.
But if the batteries are measured under a corresponding load (Attention: please apply the load only for a short time!), good batteries remain stable, with bad batteries the voltage drops quickly.
Interesting. Today I noticed my PIR did not update the lux value for more than 8hrs. So I checked the battery status:100%
Then I took out the battery, waited a few seconds and placed it back again, immediately the lux value was updated and battery status has gone to 87%.
Now after 2 hrs its still the same battery value and lux is being updated regularly