What can trigger a motion false alarm?

I have a SmartThings motion censor in an unfinished portion of my basement. The purpose is to turn the lights on when I walk in there. In that room is mostly stuff that is sitting for storage. I have 2 servers running (a large NAS & Blue Iris server) along with all of my networking equipment. I had the motion sensor mounted facing down attached to an AC/Heating duct. The motion sensor was triggering all day for the last couple of days. I did a bit of research and saw that the duct wasn’t the best choice so I pulled it down and just sat it on a table. Still getting false alarms. I then figured it was bad, swapped it out with another one. Now the new one is triggering all day and the other one seems fine. It is something about this room. What could be triggering the motion sensor?

I don’t have mice / rats.
I ain’t afraid of no ghosts, but I don’t think I have any.

This FAQ should help.


Same here…!

I move it again this morning. Both the ducting and shelf had some minor minor minor vibration. Not even enough that you can feel yourself. I put the sensor on the cement floor this morning, not movement. I’ll keep you guys updated.

Vibration shouldn’t have anything to do with it, because It’s reporting “motion.” That’s actually a very slight change in temperature that moves across the lens. If you had it set up to notify on vibration, then that could’ve been the issue, but based on your logs it wasn’t reporting vibration it was reporting a moving temperature change.

Did you get a chance to read the FAQ? Since the same sensor works fine in other parts of the house, I would guess It’s almost certainly gusts of air of variable temperatures. That’s super common in a room with electrical equipment or HVAC ducts. Also very common in basements which are neither well insulated no particularly well temperature controlled.

You’ll just need to find the right location for where it doesn’t trigger.

@JDRoberts - Yes I had already read through that for this post. I’m not sure it is a temperature thing as there is no open ducts or air handlers in this space. When the AC is running I don’t feel any kind of draft. With the device on the floor it detect no false alarms. I also did an experiment. Tell me what you think about this…

  1. I took another motion sensor and put it in a small box.
  2. Closed the box.
  3. Waiting a second or two for the ST app to say that there was no motion.
  4. I ever so gently tapped the box 5 times, so lightly that there was not visible movement what what I can see. Think as hard as you would click a track pad or mouse.

It registered motion. These things don’t have vibration sensors in them, do they?

Interesting. That model doesn’t have a vibration sensor that I know of, but if you were able to trigger it that way then obviously that opens up the possibility. There are motion sensor models that are detecting temperature variance but that also have a tamper alarm which is a vibration sensor.

The temperature variations that these detect are very very small, you would not be able to feel it yourself. A person walking across the field of detection 15 feet away will trigger it. You yourself would not feel the heat change In that situation.

Network equipment tends to run hot, and many types of equipment cycle on and off. That’s enough to change the air temperature. So then you need something to move the air across the sensor. It may be that the vibration is moving the air.

Anyway, regardless of exactly what is setting it off, the solution is typically the same: find another place in the room where it doesn’t get set off.

( I should also say here that if the same device was giving false alarms in multiple rooms, then I would suspect either battery or a defective device. If multiple sensors had the problem, then I would look for a platform issue. But when it seems to be location-based, it’s usually either temperature variance or insects.)

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The ST sensor may have a tamper sensor, but don’t see it in the specs. I now my Aeon Labs does.

You can also decrease the field of view on some sensors. I did this to a couple iris motion sensors to trigger only when I walk up/down my stairs. Perhaps you can do the same and point it right where you walk in. Need to figure out the triggers to turn off though, if the field of view is not seeing you work in there.

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I found a new place that hasn’t had a issue yet today (that is not the floor).

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Vibration is likely the root cause. The sensor thinks something in front of it is moving due to the vibration but in fact itself is the mover.

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Maybe your sensor moved in the box when ypu tapped the box and it sensed the motion from the box moving because it moved

It’s been a while since I reported this issue and I have done some testing since then. For 24 hours I set a ST motion sensor and a Lowes Iris sensor right next to each other in a room that no one (person or pets) entered for the same 24 hours. The ST sensor had 6 motion detections per hour (on average). The Lowes iris sensor had 0 over the entire 24 hours. I then redid the test with 3 ST sensors and 3 Lowes Iris sensors in different parts of the room. Again, the ST sensors on average had 6 motion detections per hour per device. The Lowes iris sensors had 0.

And this is why I recommend Iris Motions, Contacts and Power Switches. They are all pretty rock solid and I paid on average $12 per device. The deals come on Lowe’s often enough.

Yes. My testing above is one reason I have only 6 ST motion sensors and over 25 Lowes Iris brand. I’d really like to give ST my money, but their devices either suck or are over priced.

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Oh. That’s something that ST should fix then.

i get one or two false positives a week using irs version 2 motion sensors in my master bedroom closet. closet contains two servers, network dvr, Honeywell alarm equipment, and safe. I never get false positives off of my Honeywell hard wired motion detector in same closet (has opposite view). Smarthings needs to get certified motion detectors to be used with alarm functionality.

I have been having problems with my ST motion sensor as well. It’s installed in my garage. According to Action Tiles (just started a free trial) it’s at 100% battery. Most days when it’s armed I seem to get several alerts of motion detected. I have a camera in there so I check it sometimes but with all the false alarms I don’t bother checking anymore. Could extra motion sensors in the same room cause issues? I recently installed a new garage door with motion sensor on the wall plate to turn the opener lights on when you enter the garage (not using opener). Plus the Arlo Pro camera motion sensor is in there as well.

I’m getting tired of the false alarm from my motion sensor i placed on top of my front security door. I’m getting an alert every few mins. I think this is not made for outdoor as my other motion sensor in the house hallway work perfectly. I turned it off…

Believe it or not, a tiny mouse is setting off a Smartthings Motion Sensor numerous times each night in my kitchen. I’ve been sat on the couch watching TV when the kitchen spot lights suddenly come on and I see him scurrying around the kitchen cabinet skirting.

I would never have thought this possible as my Botvac vacuum doesn’t trigger any sensors throughout the house whilst on a cleaning run.

Have set numerous mouse traps around the house but he’s having too much fun setting off my alarms and turning my lights throughout the night. :unamused:

I have the same problem with fhe everspring sp816 sensor. Seems to happen at particular times