False motion activations on SmartThings motion sensor

Hi everyone.

My HE setup has been working like a charm for the last several months. However, about 2 weeks ago, I started experiencing repeated false motion activations on one of my SmartThings motion sensors. I have it hooked up to hue bulbs via RM, so the motion will turn on a series of bulbs.

Based on the logs, it appears that the sensor is just activating on its own every 30 seconds or so. This happens at all hours of the day. Finally just took out the battery and set it aside.

Then last night, the same exact issue started with the second (identical) SmartThings motion sensor. After a bit of HE updating and battery magic on the device today, it appears to be working properly.

Can't tell if this is a device issue or a software issue. And I suppose I'm sharing this to see if anyone else has experienced this type of issue.

If it happens, I'll share actual logs, though I can tell you that there's nothing special there. The sensor just goes active and triggers the rules...


I donโ€™t recall seeing this. I wonder if it might not have been caused by a low battery?

I was an ST user since the Kickstarter until I jumped ship in Jan; Oh what a difference.
That segue leads to my oberservations of ST motion sensors over 7 years. :slight_smile:
Any time I had a permanent motion event or, more common, a trigger every 60-90 seconds even when there is no action has always been the battery.

@Sebastien and @dnickel - So, at the time I first started experiencing the issue the battery was registering at a bit above 80% in HE on both sensors (82/83). So, if it was a battery issue, then it wasn't a "low battery" issue. Of course, on the first sensor, it didn't take too long for the battery to drain to 0 after continuous activation, but still.

On the second sensor, I just removed the battery and replaced it with the exact same one, which seems to fix the issue. That DID NOT work on the first problematic sensor.

I'm awaiting new batteries from Amazon anyway.

I can tell you that the v2 of the ST motion sensors with the 2450 battery die at 75% for me.
I have had quite the time with these as you have buy Panasonic or Eveready (if I recal correctly) and not Sony. All these are quality batteries but the side wall does not make contact with the conector in the device as the wall is not high enough.
I have had to put tiny metal jumpers in for non-compliant batteries.
Sadly, I even tossed one out thinking it was bad on a battery change and rescued one from the trash only after I took it apart to see what was really up. It now has no motion but lives in the freezer as a temp sensor.

A long shot but if you have any radio transmitters like a wifi router or device nearby (probably would have to be within several inches) it could interfere with the motion sensor's internals, and would become more pronounced the lower the battery voltage.

@dnickel - I hope that's not the issue, but I suppose it should be easy to test for. Will try that and confirm in this thread at some point.

@ha_migrant - I thought about that initially, but nothing of that sort in the setup has really changed anywhere near those items. So, unlikely. But that was my first inclination.

For anyone looking at this thread in retrospect, it appears that everything is now working fine. In the first sensor described above, I replaced the battery (despite HE showing 80% battery remaining). In the second sensor, I simply removed and reinserted the same battery.

In both cases, false activations seem to have stopped, at least for the time being.