Sensereo MS-1 Interlink: Okay, This Is Why I Want a Smart Smoke Alarm

The Sensereo MS-1 Interlink is a Matter-over-Thread smoke alarm with local alarm-to-alarm Interlink.

Disclosure: Sensereo provided two MS-1 Interlink smoke alarms for me to test. I’m also a Sensereo affiliate, so purchases made through links in this article may earn me a commission at no additional cost to you.

I’ve been testing the Sensereo MS-1 Interlink, a Matter-over-Thread smoke alarm that integrates with platforms like Home Assistant and Google Home.

And after I installed them and looked at the device in Home Assistant, my first reaction was basically:

Okay… that’s cool. But why do I need this?

I’m a smart home guy. Of course I like being able to see that a smoke alarm is online, check its status, and monitor things like battery health.

But it’s still a smoke detector.

I should still physically test it periodically. It still needs to scream at me whether Home Assistant is running or not. This is one device I absolutely do not want depending on my latest automation experiment to do its primary job.

So initially, the smart features alone didn’t really sell me.

Then I tested Interlink.

This Is the Magic

Triggering the Interlink test on one MS-1.

The second alarm responds through the local Interlink connection.

The two MS-1 Interlink alarms communicate directly with each other over the local Thread mesh network.

When one alarm detects a problem, the linked alarms can sound too.

I tested that directly with the two units Sensereo sent me using their recommended Interlink test procedure.

And it works.

Alarm one talks. Alarm two talks.

That’s when the product made sense to me.

Because the important thing isn’t that Home Assistant knows there’s smoke.

It’s that the humans know there’s smoke.

Maybe your dog needs to know too. An alarm near a kennel could sound even if the original event happened somewhere else in the house.

Or maybe you’ve got a detached garage, workshop, basement, patio area, or some other space away from where you normally spend your time.

Maybe your house has multiple levels. Maybe you play loud music. Maybe you’re a hard sleeper.

Interconnected alarms become more useful as the distance between rooms, floors, or separate spaces increases.

I’m not exactly living in Mansion Manor, but the farther apart those spaces get, the more useful interconnected alarms become.

Matter is the Bonus

The MS-1 uses Matter over Thread for its smart home integration. I tested mine primarily with Home Assistant, and I also successfully added one to Google Home.

The MS-1 exposes smoke, battery, device-health and self-test information in Home Assistant.

Home Assistant exposes quite a bit from the alarm, including smoke state, contamination status, sensitivity, end-of-service status, battery information and remote self-test.

Remote self-test is particularly useful. Home Assistant can tell an individual alarm to run its own test without you climbing up and pushing the button.

I did run into one strange battery-reporting issue during testing. Initially, Home Assistant showed 0% battery and 0.00 V, even though the unit was new.

Sensereo explained that battery information updates roughly every 24 hours and can temporarily show zero after commissioning or moving the device. This is the Matter battery by the way, not the alarm battery (they are separate).

Sure enough, after leaving mine connected and stable, it updated normally.

It now shows 99% battery.

So they were right about that one.

One Thing I’d Still Like Matter to Know

Home Assistant can remotely start a self-test on an individual alarm.

If I trigger a self-test from Home Assistant, it tests that individual alarm.

It does not start an Interlink test across all of them.

I’d love a separate Test Interlink command. If I had alarms spread throughout a house, being able to start one full-system test and walk around verifying every alarm would be genuinely useful.

There’s another limitation I noticed.

If Alarm A detects smoke and Alarm B starts sounding because of the Interlink signal, Alarm B does not separately tell Home Assistant that it is sounding because another alarm triggered it. Alarm B doesn't show anything.

Sensereo explained why. The Interlink signal is handled locally between alarms over Thread and isn’t currently passed up through the Matter application layer.

That makes technical sense, but I’d still like Home Assistant to eventually know the difference between:

"Smoke originated in the garage. The hallway alarm is relaying it."

and:

"Both the garage and hallway alarms independently detect smoke."

Those are two very different situations.

That kind of extra context is exactly what could make Matter more than simply another way to connect a smoke detector.

That’s What Justifies the Smart Part

Traditional interconnected smoke alarms already solve the basic problem of making multiple alarms sound together.

What interests me is what Matter adds on top:

• Remote status & notifications
• Device health & battery information
• Event history & self-test
• Custom automations

And potentially, someday, richer information about what’s happening throughout the alarm network during an actual event.

That’s the part that can make paying for a connected alarm worthwhile.

So Far

My first impression of a smart smoke alarm was basically:

Neat. It’s online.

After testing Interlink, my impression is different:

The smart part isn’t what convinced me. The alarms talking to each other did.

Matter then becomes a useful layer on top rather than the entire reason the product exists.

I had some commissioning weirdness early in testing, including an “uncertified accessory” warning in Home Assistant. After resetting and recommissioning the alarms and refreshing my Matter environment, that disappeared. Both alarms are now commissioning normally in Home Assistant, and my Google Home test also completed successfully.

At this point, Interlink is working consistently, Home Assistant remote self-test works, and the battery reading has settled down and is reporting normally.

I’d still like to test four or five of these spread across a remote network, because I think that’s where Interlink goes from a neat demo to something genuinely useful.

Sensereo supplied two units for this test, though, so for now the two-alarm setup answered the question I started with:

Why would I want my smoke alarms to be smart?

Not because I need another device on a dashboard.

Because the alarms can handle the important part locally — making sure everybody hears the warning — while Matter gives my smart home useful information on top of it.

Product Link: Sensereo MS-1 Interlink product page