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Mon, Jun 14, 2021 7:42 AM

Motion Sensor Issue

Hello All,

I have had 2 motion sensor false alarms in the past month.  Bit frustrating.  The alarm is setup at a home about 2 hours away.. so not that easy to check on it right away.

After the first time it went off.. I was able to go and check and there were no signs of intrusion.  Also I didn't see any reason for the false alarm (the sensor didn't fall off the wall, etc.).

After the 2nd false alarm.. I had a neighbor check.. and there were again no signs of entry.

What could be going on here?  Defective sensor?

Couple things to note.  There are no pets at the house.  The sensor is not near any heater or A/C vents.  There is no sunlight shining directly shining on it.  I didn't see anything fall or anything that could have triggered it.  We have the 3rd gen system and got it 2 years ago.  No issues until I started to get these false alarms a month ago.

I thought maybe it was something with the heat levels changing in the house (with the sun going down or something).  First false alarm was in the afternoon I think (I can't see now with the limited timeline).  But the 2nd false alarm was at 1:06am so that would seem to have nothing to do with the sun.

Any thoughts?  Thanks much,
Peter

Community Admin

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Hey Peter,

Yep, sounds like you already know a bit about how the Motion Sensor works.

For those just joining us, our Motion Sensors are the passive infrared type - so they're looking for sources of heat that are in contrast with the rest of the room, and are moving around.

When looking for culprits for a false alarm, we're looking for anything at all that generates heat - pets, AC vents, and sunlight bouncing off objects, as you mentioned are good guesses.
One time, I was working with a customer over the phone, and we figured out it was actually their office laser printer! It would turn on periodically to stay ready for any new jobs, so that explained why it was triggering the alarm at such random times.
Whatever the trigger is, it must be somewhere within the field of view - so it would help to list anything there, even if it's unlikely to be the actual cause.

Though it's also possible that the sensor itself is messed up. You can try putting it in a drawer, so we know there's no possible way it's actually picking up something in the room. If it still triggers, we know that the sensor should be replaced.
(Of course, don't forget to set the sensor to Secret Alert during Home or Away modes, so there's no more danger of accidental dispatch!)

- Johnny M.
SimpliSafe Home Security

6 Messages

Thanks Johnny.  Appreciate the feedback.

The weird thing is that we haven't changed anything with the placement of the sensor or any 'things' in the field of vision of the sensor.  No new appliances or things that move.  At first I thought maybe it had just fallen off the wall or something.

I'll try the idea you mentioned.  Putting it in a drawer and then see if it registers any alerts.  Then I think we could say the sensor is defective?

I think the recommendation is that you don't want any sunlight to directly hit the sensor as it can prevent it from properly detecting the motion / temperature changes.  Ours does face a sliding glass door.. but when we leave and have the system armed.. we have the curtains closed so sunlight never really becomes an issue (as far as I know).

Thanks,
Peter

Il y a 1 a

Is it OK to have a motion sensor pointed towards a window? I just ordered a few for some small rooms and one or more windows will probably be in their field of view.

Thanks!

Community Admin

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2.9K Messages

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public_74,

On the one hand, window glass should be providing a bit of insulation there. But then if sunlight comes in directly, and if the Motion Sensor is ever pointed at it, that could be a problem. Especially if that sunlight is filtering through clouds or trees, as that could trick the sensor into thinking that there's a warm body moving around inside the room!

- Johnny M.
SimpliSafe Home Security

Advocate

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108 Messages

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@prberg2
The only time I've had a false alarm from a motion sensor that I couldn't explain seems to have been solved by replacing the battery.  My motion sensors were trouble free for years then I got an alarm in the middle of the night while we were away on vacation.  An independent camera recording in the room shows there was nothing moving and it was about 2:00 AM.  I figured the batteries were getting old/low enough to somehow affect the sensor but not give a low battery notification.  Same thing happened in a bedroom.
Other types of sensors have given low battery notifications over the years, but I don't recall ever seeing one for a motion sensor so I just change those every few years.   The batteries aren't too expensive for how long they last.  It might be worth it to change the batteries every other year when you are there as just another maintenance item.  This of course depends on how long the sensors have been going on their current batteries.  
Certainly worth trying the other troubleshooting methods mentioned.