ITTSB.EU Blog Forum
ITTSB Blog Specific => ITTSB General Discussion => Topic started by: Kiriakos GR on August 16, 2015, 07:42:31 PM
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I own three PIR (motion) sensor with LED lights, those serving me 24/24 365.
All of them are placed in special locations which direct sunlight can not get to them.
Because my gadgets are battery powered I thought that they starter loosing working range in meters (regarding detection) and I recharged all their batteries, unfortunately this it did not improve their performance.
I thought that is impossible all three to go bad simultaneously, and then I started realizing that the problem seems to be the environmental temperature which now in August is identical with the human body temperature.
The problem seems to be that at such conditions, this PIR (motion) sensor (detection working range) is now about 60% less at room temperature of 32 Celsius, than when room temperature is at 15~22 Celsius.
PIR (motion) sensors are used in many applications, one of them is at burglar alarm systems.
I am assuming that not all PIR (motion) sensor are build equal, and some will have more sensitivity by design, but this finding of my it did fill me up with second thoughts.
Mostly because of the assumption that many burglar alarm systems at budget price, probably them are not able to work properly in the hart of summer.
(https://dmohankumar.files.wordpress.com/2011/08/pir-sensor-3.jpg)
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You are correct in your observations. The range is impaired during the summer months and conversely enhanced during the winter months. This is because air temperature, specifically its density, is a significant factor to be taken into consideration. If you have a sensitivity potentiometer on your PIR (sometimes marked "range") adjust it accordingly and hopefully that will fix it. For high security applications consider using microwàve sensors as opposed to dualtech units as that could put you back to square one. Remember if you overincrease the range you may get extraneous triggering in the winter if you have brought into range things which were not there before. Hope this helps and good luck.
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If you have a sensitivity potentiometer on your PIR (sometimes marked "range") adjust it accordingly and hopefully that will fix it.
Personally I never come across to PIR sensor with range adjustment, I am now assuming that any sensor designed for outdoor use, it should have one.
Our forum Moderator he is an burglar alarm specialist.
My very own PIR sensor application this is a humble stair lights ( On / Off ) :)
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Its a true that many PIR loose their sensitivity during high temperature.
Their design is to detect human temperature ~37degrees, when enviroment temperature reach these values (on hot summer days)
its difficult to seperate the presence of a human body from detection area.