Battery backup for Sense itself?

This is nothing to do with Solar. We have brownouts here for few seconds to maybe even an hr (rare). All my n/w devices are UPS driven so during such brownouts I can continue broadcasting (Wifi). Is there no way to attach a 100W or so UPS to Sense monitor itself? In this way, Sense can continue functioning during brownouts and effectively provide a way to consumers track brown out time periods?


There’s an inherent issue with attempting to do that. Sense uses the two live input legs (and the neutral) for the voltage signal along with using one of those legs to power itself. Meaning: the voltage readings used to extrapolate power (volts x current from the current transducers) are dependent upon the actual voltage input at those legs. I don’t know what the “brownout” voltage for the Sense itself is (maybe <110V?) but you can see the issue with “injecting” voltage into Sense to keep it powered. It will essentially equal “false data”.

I suspect the calculus was: Sense is a cloud-based device and can report as “down” during a power failure and during a power failure the panel signal/data (=zero/NA) so why attempt to send anything out?

The brownout time period, to a reasonable degree of accuracy, can be established from the Sense monitor being polled by the Mothership.

As above, not really possible. In order to provide backup power to the Sense homebase, you’re effectively more or less providing power to some or most of the house as a direct side effect. So you’re not really in a blackout out at that point.

FWIW Sense will eventually tell you if it’s offline by sending both an email and/or a push notification to your phone depending on the settings you select - they can be found in the “Notifications” tab in the setup menu.

In effect, that provides you the end goal you seem to want anyways, correct? Notification the power is out?


There seems to be some confusion (in general) about the nature of Sense and the cloud. I realize this is obvious to many, but if power is killed to the Sense monitor it’s not some last-second event that the monitor sends out an alert. No, the Sense Mothership is polling the Sense monitor and sees that the connection is lost so it can repeatedly send out notifications (if needed) until the monitor comes back online.

Sorry, I am not buying this argument. The clamps are connected to the power source. Okay. Great. Power goes off, the Sense goes offline.
Now if there was a USB port or some similar port available into which a secondary power source can be connected, that power bank can now power Sense till such time main power returns. Feed of power bank back into main power can be easily controlled. Charging of the power bank itself via main can be done thru an isolated circuit whose wattage is accounted for.
The whole idea is for Sense to be able to detect brownouts and work in tandem to Wifi connections which in a home might be already UPS driven.
Someone mentioned notifications - they don’t work if power goes out. Sense immediately goes offline and notifications are killed immediately. I just now tested it.

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NO … it does NOT. I have kept Sense offline via a power OFF situation and also Wifi down situation. When Wifi is down some notification did come but initially. In case of power off - NOTHING.

Are you saying you didn’t get notified by Sense that your monitor was down? Mine was out for about an hour period a few weeks ago. I noticed the alerts only came on the hour. So if you monitor goes out at 5:01 you’re not going to be notified until 6:00.

Do you have your preferences set this way?

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You cannot power the Sense from USB or otherwise from outside the panel and keep it within US electrical code. This is a device that is built to be inside your electrical panel and there are loads of rules to prevent what you are suggesting. And before you say “then put a USB power brice inside the panel”, that is also not ok without severe modification to your panel.
If Sense built a device that was designed to ONLY live outside your panel, then maybe they could do such a thing but the question is why. If the home is without power, there is nothing for it to report. If the home has a deep enough brownout for the Sense to drop offline, then again, there isn’t anything for it to monitor.

You say “the whole idea is for Sense to be able to detect brown outs”. I have never heard this claim before on these forums not in their marketing. The whole idea is to be able to monitor power usage of devices in your home. Power quality monitoring or even voltage monitoring is not something I believe Sense has ever claimed to monitor. Sure you can see voltage on once screen, but monitoring said voltage is not a feature of the device.

Alerts - As mentioned by @waterboysh, the watchdog for a device being offline is not instant.

And as @ixu said, the alert does not come from the monitor, but from the cloud. There is no way for it to come from the monitor. The Sense monitor doesn’t know its going to lose power, so it can’t send an alert saying that it is going to lose power. Also, the alert is not “your device has lost power”. it is “your device has gone offline”. You will get the same alert if your internet drops out and the Sense servers don’t get a response. All they know is that the Sense hasn’t dialed home in over 30 minutes.

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If you really really wanted to you could, while keeping to the NEC, put a 240V plug on the Sense inputs and then plug it in to a 240V UPS. This would keep things working BUT then you have an issue: the voltage signal to the Sense, which is not through the CTs but through those input wires, is not going to match anything that makes any real sense to measure unless that UPS is also powering equipment fed by your panel … so you are back to fundamental issues that @ben is highlighting.

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My main problem with it is in central Florida on Duke I get short outages, like for 1 second or so. Those seem to lock up the sense device. It would be nice if it had a small internal capacitor to hold it alive for a 10-15 second glitch. Longer outages don’t seem to crash it, but the real short ones do.
If it had a little more capacitor maybe it could stay on until a generator. Would also be slick if you could chose to use the solar as a generator load monitor.