1/10 Second Power Outage = Sense Offline


Just so I’m understanding fully, you got an alert that power to your home had gone out for 5 seconds? That’d definitely knock Sense offline so that sounds normal. But it should’ve come back on when power was restored, pretty soon after that 5 seconds (unless the outage continued into an extended brownout). You should write into Support about this as it sounds pretty odd and maybe a hardware issue.


@RyanAtSense I have corresponded with support about this. Their only solution is to replace the monitor, which (a) I don’t think will solve the problem based on other user reports here; and (b) will cause all of my learned devices to be forgotten, which is a major setback.

Monitoring Sense

This came over on Facebook so I figured I should update you all here as well.

We’re pretty sure this is a hardware issue. We’ve done quite a bit of testing on some monitors we received from users in this thread and via Support, and that’s what the data is pointing to. If you’re experiencing frequent brownouts that force your Sense monitor offline and your monitor is then unable to recover on its own, please reach out to Support. Do note that if it is diagnosed as a hardware issue and you’re offered a replacement Sense monitor, you’ll lose your existing Sense data.


I just installed my new Sense today. Right after the installation, which went fine, I decided to upgrade the firmware on my wireless AP. This process also involves a quick AP reboot. To my surprise all devices around the house reconnected perfectly except Sense, which went offline and needed a full breaker reset to get reconnected. It showed all the symptoms people indicated in the thread but this was not related to a power outage event on the Sense side but was more related to a wireless disconnect (or IP address re-acquisition). Please mention this to the developers as a simple wireless reboot should not cause such disconnect behaviour and as a result prolonged data loss. It should also be easy to simulate such scenario in a lab.


You really shouldn’t need to do a breaker reset for Wi-Fi, so that’s odd. Maybe it had something specific to do with the firmware upgrade? Keep watching and if you have to reset for a Wi-Fi outage again, definitely let us know. As of now, it sounds unrelated to the issue taking up the bulk of this thread. I’ll pass this along to the team.


@RyanAtSense MachoDrone has had Sense offline several times last winter/spring.
Rebooting Wi-Fi router was easier, more accessible, and faster recovery compared to flipping breaker to the Sense Monitor.
MachoDrone has remote access to his Wi-Fi Router, so rebooting Wi-Fi was easily done while at work.
MachoDrone has not probed network packets nor has he read logs on his side of the network devices.
… … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … V heart V


Greetings, all. Your friendly monitor software engineer here…

We have a tentative solution to one of the issues mentioned in this thread.

For those experiencing a monitor outage which is associated with a router reboot but not an interruption of line power:

There is a DNS cache on the monitor which is being poisoned in some way during a router reboot. The monitor doesn’t particularly benefit from the DNS cache, and it appears that disabling the cache allows the monitors in this scenario to survive the router reboot without requiring further intervention. This fix is still in testing, and if it’s successful, I will roll that change out to everyone in the next software update.

Independent of the aforementioned software issue, there is another issue where a brownout or quick interruption of power can temporarily disable the monitor, requiring a manual power cycle. This scenario is not under software control, and will not benefit from the above fix. (That said, it will be impossible for you guys to know if you’ve hit the brownout issue, versus hitting a DNS cache poisoning brought on by a router reboot due to the power outage. They look the same from outside the monitor itself.) The relative prevalence of these two issues is unknown right now.

I hope you can all be patient with us as we work through these issues. We have lots of good improvements and fixes coming down the pipe to all of you.

WiFi Network Timeout/Recovery

Installed Sense about 3 weeks ago. We had a momentary power outage (a blip/bump) today and Sense went offline.

Once I got home, I had to power cycle Sense and use the App to reconnect Sense to my WiFi. Lost the data between the power issue and the power cycle.

Hopefully this gets fixed in the future. Sense is the only device in the house that I had to do anything too. Everything else reconnects to the WiFi without issue.

(Other than this event, Sense has been very successful in my house).


To: @rob.koekkoek

Review these two posts previously entered. Maybe one of these options could provide you with a solution. I haven’t had any problems with power outages or “momentary power outage (a blip/bump)” since I installed my additional relay.

May 13th

May 22nd


Thanks @Dcdyer! I’ll try the IP Address Reservation with my Wifi first (since it’s easy and free). If that doesn’t work, I’ll consider the TD69 installation. That’s a very creative solution. Kudos to those that thought of applying it! With that said…hopefully there aren’t many more power issues in the near future.


We had a number of short power drops the other day while some equipment failed elsewhere in the neighborhood. With the TD69 feeding the Sense monitor, I didn’t have any issues with the monitor coming back online after the dust had settled.

Brief Power Outage and Cable Modems

An update here:

I’ve continued to have issues with the monitor dropping offline during power “blips”. Finally I decided it was worth the trouble to have Sense Support replace the hardware, which was their suggested next step to resolve the issue. I started from scratch during this process (there is no data migration process) and lost all of my detected devices.

Unfortunately, the replacement monitor has not solved the problem. The monitor dropped offline and stayed offline for 12 hours last week during a windy night while I was out of town. Interestingly, the monitor recovered without any intervention on my part. I suspect the sequence of events leading to this was that a <70mS power interruption occurred, which locked the monitor up. Then, 12 hours later, a >70mS interruption occured, triggering the TD-69 to drop power to the monitor for 30 seconds. This likely reset the monitor and brought it back online.

Unfortunately, support doesn’t seem to have any ideas here other than adding a UPS to the power supply, which is a difficult thing to do in any NEC-compliant way.


So how does SENSE support suggest adding a UPS system? Did they provide diagrams, photos or sketches? Have they actually tried this or is it just another quick reply without any supporting documentation? Is their suggestion NEC-compliant? I’m curious to understand their solution.

PS. To @pswired: My system has been working correctly since the TD-69 relay addition. I started with a 8-minute delay on the timer and have been slowly moving it down to a 4-minute delay. Maybe the reason for no past ‘SENSE restart’ failures is that we haven’t had many power outages recently or the type of outage is correctly handled by the TD-69 relay. Thanks for posting an update on your outage events. Keep us informed if you have another one.

It seems to me that maybe SENSE Support could provide a monthly report on the number of times the user’s SENSE monitor unit re-boots itself each month. I am sure there is some statistical information that could be gleaned might help all users determine if they are having excessive outages or monitor reboots.


I spoke to Support and this is being brought to our lead EE to try and figure out what’s going on. I’ll let the Support agent update you personally but I’ll also update the thread when I know more.


This is the second time I’ve had a power blip where my home gets a surge and Sense gets knocked offline. The fix is to go my electrical box and flip the breaker that Sense is on TWICE. At least with the new iOS update, I know right away now. Is this a known issue that will be worked on?


Given that they put notification in the last update, yes, it’s a very well known issue. I think I’ve been lucky to have it only happen once so far.


@marcbh, this is a known issue and was a motivation in developing the offline monitor notification feature. We’re currently testing potential solutions to this issue.


So 1 year later this is still happening. I’m having a real hard time understanding what is soo hard in having this device be more resilient in network recovery. It really doesn’t matter in my mind what the situation is, small power blip, Network router reset etc… We really should be at a place where for the most part this simply doesn’t happen. Either the device is running or not. If it is, recovery should not be a problem period, i.e if i’m running and keep retrying reconnect every x whatever. That’s not what’s happening here, it has to be far more rudimentary to the design of the device.
And more importantly as someone pointed out much earlier, if that design doesn’t incorporate the most basic means for determining via stored logs when this happens, we’ll never know!?


BTW, I have more than 25 years of development and networking experience. More than happy to help, not to mention I can very easily reproduce. The biggest problem I see, however, is if the device does not show enough information leading up to the problem, or any, or after, how can you possibly fix? In what I can see the device dies in the slightest of scenarios , and makes me believe it’s a hardware design flaw, if there is not a feature to enable stored logging of some nature, and things are actually logged, how can this be resolved?


@davi1td - I agree with your statements.

Read though this very long blog. You will find users with the same problem you are experiencing. There are some ‘home-grown’ user solutions listed.

SENSE will want to exchange your ‘orange’ monitor unit, but that did not work for @pswired. See his latest blog. Your comments are very similar to my own in an earlier blog in the:

1/10 Second Power Outage = Sense Offline thread.