Hi - I currently have 2 motion sensors, both in the hall, that are showing with a red ‘!’ in the device list and are currently ‘unavailable’.
I only changed the battery on one about 3 weeks ago so it surely can’t be that but I can’t find anywhere for guidance.
Help?!
Fixed. Unbelievably the battery has been cained through.
I’ve managed to chew through the batteries in 2 motion sensors and 2 multi sensors so they all say offline. Can I find CR2450 locally - nope.
And I’ve found that you do need duracel or Panasonic batteries as others have a different side profile so the contacts don’t work; dodgy hardware design really.
One of my sensors has become unavailable this week. The Last Battery Status was 89%. If I pop the battery out and put it back in, the sensor becomes available for a few minutes and goes again.
Can it really be a dead battery after only about 2 months use?
Best to get a multimeter and measure the voltage of the battery. If it’s 2.8v or less then throw it away. If not then common reasons for sensors dropping are interference or mesh issues. I find osram bulbs a common cause for dropping sensors.
I’m having strange motion sensor battery problems too… with all SmartThings types that require varying battery types.
I’ve swapped the battery with another sensor downstairs and the problem remains with the same device. It’s not a battery issue but connection to the hub. It’s been working for a month or so, so I’m not sure why it would suddenly fail?
To be honest a month is anot a great deal of time. I’ve had things do that in the past. It’s a (very) weak radio device powered by a feeble little coin cell battery. There are lots of sources of interference everywhere both internal and external to your home (which are much harder to avoid). I just have a lot of smartthings outlets in every room of the house and removed most of my smart bulbs from directly connecting to smartthings and most of these issues started disappearing.
Since I swapped the batteries and re-seated them, both sensors have stayed connected so far. Hopefully the problem was just the contacts to the batteries.
I’m having the same problem. All my Smartthings with motion sensors have become “unavailable” but the last battery status was 67%. This is too much of a coincidence, I think they are messing with the system. I’ve tried putting a new battery in, to no avail. 
Also, my husbands phone has suddenly stopped working and always reports as present.
Basically this security system is far from being secure.
I’ve tried their support desk but I’m just getting “try this” standard responses.
Hi there, I was seeing the same issue with 3 ST motion sensors, having to reset these at least every day! I found out it was due to my Wi-Fi channel overlapping with my zigbee channel, resulting in weak zigbee mesh.
I changed my wifi channel (super easy) and no issue after a few days. Happy with my smart home now!
I have a st outlet kept disconnecthing from the hub even I have one replaced, 2.4ghz network seems very hard to work with ZigBee as I have lots of other 2.4ghz neighborhood and the hub cannot change the channel manually unlike my hue bridge , I already reconfigured all the devices once due to a replacement st hub, 2.4ghz just seems a bit crowded
