20 January 2012
A small percentage of customers report problems like the ones listed below but since we do get the reports we thought we would write a blog on the best practices for using a PIR motion sensor like the ones used in Mr Beams motion sensing lights.
In Mr Beams products we use a PIR motion sensor to detect motion. PIR stands for Passive InfraRed. A PIR sensor detects infrared light radiating from an object. This equates to a rough measurement of the heat generated by an object for example a human body, an animal or a car. When there is a change in the measurement of heat in the field of view of the motion sensor, such as someone walking through the area, the motion sensor is triggered and the Mr Beams light turns on.
To understand the best practices of using a PIR motion sensor, it is important to understand that the sensor will always be detecting the background heat - for instance the wall or the ground. This will be determined as the normal state of temperature and only when there is a change in the detection area such as something that generates heat moving in that area that changes it from the normal state, will the sensor detect motion. Thus, a PIR motion sensor will not detect a stationary object even it if has a different temperature than the background.
So here are is a list of problems and tips for addressing those problems for the best operation of a Mr Beams PIR motion sensor LED light:
1. Unintentional Objects Moving in the Background - False motion detection can occur with anything in the area that may be in motion that has a different temperature than the surrounding temperature. In difficult environments, strong wind blowing leaves on trees or similar object can trigger the motion sensor. This is because heat from the day may be trapped within the leaves of trees or other objects. If it is possible to mount or direct the Mr Beams LED light where the field of view of the motion sensor can avoid objects in the background that may be blown by the wind, that is recommended.
2. Moving Air - Moving air may have a different temperature than the background environment. Vents blowing air may cause false detection because the air from a vent may be a different temperature than the background. It is recommended that a motion sensor be mounted or directed away from an air vent. To avoid wind blowing outdoors, try to place the sensor in an area that may be sheltered from the wind.
3. Electrical Noise Sources - A PIR motion sensor is a very sensitive electrical circuit. If it is mounted close to an electrical motor or generator, the circuit may pick up electrical noise from the motor or generator. In one customer example, the customer had mounted the Mr Beams LED light in their RV inches above a generator that was used to provide power at night. The Mr Beams LED light false triggered when the generator kicked on. The customer moved the LED light just an additional one or two feet away from the generator and the false triggers stopped.
4. Low Battery - Low battery levels can create a problem with the motion sensor. When the batteries are almost completely drained, the motion sensor may start to false trigger. If after prolonged use false triggers start to occur, either check or change the batteries.