Meross Thread Smart Presence Sensor MS605 review

Meross Thread Smart Presence Sensor MS605: Introduction

The Meross Thread Smart Presence Sensor MS605 shows how far presence sensors have come on. Although relatively cheap, this model has a PIR motion sensor, mmWave detection (with three zones), a light sensor, and Matter over Thread compatibility, so it will work with whatever hub you happen to have. 

At its best, this sensor offers a lot of flexibility, but for all its good, it takes a lot of work to get it detecting reliably, and the irritating Bluetooth setup doesn’t help. Is this the right sensor for you? Read on to find out.

Design and components

• Bulky
• Flexible stand
• Requires one CR123A battery

Most smart home companies have got the memo that every device needs to look nice (well, as nice as a sensor possibly can). Look at the SwitchBot mmWave Presence Sensor, and you’ll see a sleek, curved box.

The Meross Thread Smart Presence Sensor MS605 is a bit of a throwback to the early days, and it’s very boxy, with a cheap protruding plastic dome for the PIR sensor. It’s quite a lump and sticks out more than the competition.

This sensor is very flexible, though. Its stand hinges at the back, making it easy to position the sensor and point it where you want it. And, it sticks to the wall via the provided sticky Velcro strips, making the sensor easy to remove when you need to replace the battery.

A single CR123A battery powers the Meross Thread Smart Presence Sensor MS605 and should last up to three years, though the number of times you activate the sensor will affect that.

Features

• Configured via Bluetooth
• Matter-over-Thread compatible
• Operates as three motion sensors and a Lux sensor

Although the Meross Thread Smart Presence Sensor MS605 is a Matter-over-Thread device, complete with a Matter code on the side, for setup and control you need to connect it via Bluetooth to the Meross app.

This gives full access to the configuration page, which includes setting the sensors up to work. It’s fine in theory, but to save battery life, the Bluetooth connection shuts down; every time you want to make a setting change, you need to press the button on the side of the sensor, which is a little frustrating.

For ease, the Meross Thread Smart Presence Sensor MS605 has an automatic mode that is designed to configure the sensors to accurately detect presence. Turn on any devices that cause interference, such as fans or AC, leave the room, and let the software do its job. 

This should result in the Meross Thread Smart Presence Sensor MS605 automatically configuring itself to ignore the background noise in your room.

However, if this doesn’t work (and, on my experience, it won’t), there are options. First, you can use the app’s log and tell the sensor which triggers were false positives. Secondly, you can manually adjust the sensitivity for each range bracket.

You can also reconfigure how the PIR and mmWave sensors are used. The default is to use radar first and PIR second, but you can use PIR first to pick up motion and then radar to maintain presence. Or, you can ditch the PIR sensor entirely and make it use just radar.

Finally, the Meross Thread Smart Presence Sensor MS605 is actually three configurable sensors, each one configurable to turn on at different ranges. For example, you may want it that walking into a room, at distance from the sensor, always turns on the light, but only moving closer and sitting down turns on the heating.

Then, there are options to adjust how many seconds the sensor should have motion for before triggering presence (the default is set to 0s, but you can add more time); and you can do the same thing for absence, setting a timeout. All of these settings have an impact on how the sensor works, and they play a part when you connect the sensor to a smart home system via Thread and Matter.

Depending on the system you use, the Meross Thread Smart Presence Sensor MS605 presents itself. Connecting to Apple Home, the MS605 appears as three sensors, and the light sensor appears. 

However, Automations can’t be created based on how long presence is or is not detected for, so Apple Home relies on the times set in the Meross app.

Connect the sensor to Alexa, and the light sensor doesn’t work at all.

Connect the Meross Thread Smart Presence Sensor MS605 to Homey, and you get everything that Apple Home does, but you can trigger Flows based on how long presence or absence are detected for. 

Just be careful. If you have the Meross app set to only trigger presence after 30 seconds, and then create a similar Flow in Homey, you’ll find that you have to wait one minute before the rule runs.

Depending on the system you use and what you want to do, the resulting controls can be spread across multiple apps.

Performance

• Takes a lot of configuration
• Works reliably when setup correctly

I wasn’t impressed with the Meross Thread Smart Presence Sensor MS605 at first. After using the automatic setup, the app said it was configured and then immediately showed that the sensor was detecting presence in my empty office.

I tried to manually adjust sensitivity and remove the false positives in the log, but it’s quite a lot of work, and the changes didn’t seem to make that much difference. I also reduced the time it took for the sensor to detect absence, but that also makes the MS605 quite unreliable, turning off lights too quickly, for example.

Changing the activation modes helped. Using PIR first and then radar was good. And, for my office, using radar only proved to be much more reliable. That’s good that I could fix the issue, but having so many settings and options does make the Meross Thread Smart Presence Sensor MS605 feel more like a tech product than a simple set-and-forget presence sensor as you get with the competition.

Depending on the size of your room, having the option to turn the Meross Thread Smart Presence Sensor MS605 into three motion sensors, each by distance, could be very useful and adds flexibility that basic mmWave sensors don’t provide.

Properly working, the Meross Thread Smart Presence Sensor MS605 is very good. It is quick to detect changes, and it avoided false positives. I set up a Homey Flow to turn off the lights when there’s no presence detected, and then sat very still at my desk. A motion sensor would have resulted in the lights being turned off, but the MS605 kept the lights on until I physically left the room.

Final thoughts

Unlike a lot of the competition in my guide to the best presence and motion sensors, the Meross Thread Smart Presence Sensor MS605 doesn’t require an additional hub to work, and you can connect it to any Matter-compatible Thread hub, although there are difference as to which features are exposed. Configuration via the Meross app is useful, although forcibly having to press a button to get Bluetooth working is a bit annoying, and there are then a lot of settings to play with get the sensor working reliably. Properly set up, this is a flexible and powerful mmWave presence detector, but there are simpler options available.

How we test

When we publish our reviews, you can rest assured that they are the result of “living with” long term tests.

Motion sensors usually live within an ecosystem, or a range of products that – supposedly – all work in harmony. And they are designed to offer a range of different cleaning options. Therefore, it’s impossible to use a motion sensor for a week and deliver a verdict.

Because we’re testing smart home kit all day, everyday, we know what matters and how a particular motion sensor compares to alternatives that you might also be considering.

Our reviews are comprehensive, objective and fair and, of course, we are never paid directly to review a device.

FAQs

Meross Thread Smart Presence Sensor MS605: Specifications