SR501 PIR & Stops Working in Low Temperature

Other Hardware Sensors
1

I am running the SR501 PIR indoor, with room temperature at about 30C, the PIR works fine. But when the air conditioner is turned on, the temperature drops to about 24C, the PIR stops detecting movement. I noticed when the temperature rises to 25C, it starts detecting movement again.

I was searching for answers on google, and found an article saying at warmer temperatures, the sensor should be less sensitive, as the ambient temperature gets close to body temperature. And at cooler temperatures, it should be more sensitive. What I am experiencing is, it stops working at a lower temperature.

Could anyone share any insights on this?

2

You need to find the datasheet for the PIR itself and even then it only tells part of the story.

The SR501 is a module.

You would need to do a complete analysis using tolerances of the individual components as they vary with temperature.

My gut feeling is that no one has bothered doing it.

Or you may have a faulty module.

3

The two SR501 PIR sensors I have in the basement are frequently exposed to temps below 10C.
They are in use 24/7, and are already running for more than two years without failure.
You either have a dud, or have connected it wrong, or you have it in the warm/cold air stream of the airco.
Leo..

4

I have to admit, the one I am currently using feels and looks different from my old SR501, which I have purchased many years ago. It was from the same seller, but the new one feels a lot lighter, and built quality doesn't feel as good as the old one. I will buy a few new ones to try again. Thanks.