SmartThings Community

Device Behavior After Power Outage?


This is the siren
Hobbypower AC 220V Mini Motor Driven Air Raid Siren Horn For Car Truck Alarm MS-190

The motion sensor
Monoprice Z-Wave Plus PIR Motion Detector with Temperature Sensor

The zwave switch
Aeon Labs DSC18103-ZWUS,White,US,AL001 Aeotec Z-Wave Micro Smart Energy Switch, 2nd Edition

If a battery powered sensor changes state during a power failure then ST will miss it.

For example:

1 - Contact sensor is in the closed position
2 - The power goes off
3 - Contact Sensor opens
4 - Power back on

After the above, ST will display the door as closed even though it is still open.

Closing the door with the power back on will re-sync though.

Your Aeon Labs switch will likely revert to the off position as @JDRoberts states. I can’t find any documentation on this either way so you may be better of running a test.

Some mains devices (i.e Fibaro Modules) have customisable parameters and you get to choose what happens:

I could wake my entire neighborhood up with this. It would be terrifying. They also sell a 125db model. Ha.

Not true, unless you didn’t put batteries in the SmartThings hub. That’s why it has batteries. It will run for about ten hours just on battery, and during that time it will continue to receive notifications from the battery powered sensors.

Of course, if you still have the old V one hub, it didn’t have batteries, so it goes down when the power goes out.

Are you sure? I have the V2 hub and it definitely misses ST Multi events during power down (gets stuck in the opposite state till next event occurs).

Just did another test to be certain and this is what happens for me.

Maybe my batteries are dead then… Will check!

As long as you using a device type handler which is eligible to run locally, then yes, I’m sure.

Of course, what the hub does with the sensor report is a different question. But if you have a smart lighting automation which does nothing except turn on a locally eligible light switch when the locally eligible sensor reports to the hub then, yes, that should continue to work during a power outage.

My ST contact sensor is on the list for local processing and I’m using the defult stock handler… With Internet down and using Smart Lighting I can make the my ST outlet turn on when the contact opens… So definitely all locally compatable.

With the power off to the whole house (and the ST batteries are good) the ST app does not update to the correct state when it all turns back on.

The app is going to get out of sync with the actual device states if there is a power outage. This is because the hub cannot talk to the mobile app except through the cloud. There’s no way around that at the present time.

I think, but I’m not 100% sure, that if after Power and Internet are restored you then took the hub off power all together (including taking out the batteries) and left it off for about 15 minutes and then put it back on power that it will re-sync with the cloud which should then update the app. Which might be easier than going around the house and re-triggering every sensor you have.

So as mentioned above, I have local processing working when Internet is down.

I just did another test… I put my ST outlet on a UPS and turned the power off to the rest of the house (hub, router etc) leaving the hub running on its own batteries and outlet powered via UPS.

In this setup local processing fails and opening the contact does not result in turning on the outlet. ST hub appears to miss the contact sensor event while powered on battery.

Either I have a faulty hub or local processing is designed to be disabled when on battery power (though that would kinda defeat the object right?)

Something is definitely wrong. I would talk to support. There are lots of people using sensors and switches via SmartLighting when the hub is on battery power.

I thought the local processing will still work only if you lost Internet. The battery is just for easy pairing of new devices and won’t do any automation with just battery. I would also like to know about this. I have the same test result as @RobinWinbourne.

Wow, interesting. I believe you, but then what the heck is the point of the batteries?

@slagle is it true that if the hub switches to battery power it won’t process zwave or zigbee traffic anymore?

Summary of my test results:

Hub on batteries + internet on = everything continues to work as usual.

Hub on mains power + Internet off = just local processing.

Hub on batteries + Internet off = Nothing works.

so basically during a power outage, nothing works,
even if your sensors, alarm and ST are using batteries. You need internet or main power

but when the main power is back… what happens? did you test that? @RobinWinbourne

Not the case. It will do ZigBee and Z-Wave but only devices that are eligible for local execution. If you are seeing something different please contact support.

1 Like

I have issues then… I’ll contact support at some point but it’s not really a problem for me right now.

1 Like

is there a list for the devices that are eligible for local execution?

Just to be a little more clear so I can test it again later. Are you saying local processing will still be working with no Internet and only batteries to the hub?

1 Like

Yes :slight_smile:

1 Like