Bosch Motion Detector II M for Smart Home Security

The Bosch Motion Detector II [+M] is a passive infrared motion sensor with a built-in orientation light. Bosch rates detection at up to 13 meters (43 feet), the case at IP55, and the sensor meets the EN Grade 2 security standard. The [+M] in the name means Matter: one radio module can run Zigbee through a Bosch Smart Home Controller, or Thread into a Matter system. It costs 49.95 euros in Germany, where it launched first.

I haven't mounted one, so this page is a researched summary of Bosch's published specs, the Connectivity Standards Alliance listing and German reviews, not a hands-on test.

Specs that check out

• Detection: passive infrared, up to 13 m, best mounted at about 2 m height. Sensitivity and light brightness are adjustable in the app.
• Pet filter: designed to ignore animals up to about 80 cm tall.
• Orientation light: switches on with motion in low light and off 30 seconds after the last detection. It can also signal that an alarm system is armed.
• Protection: IP55, which is dust and water-spray protection and fine for a porch or garage, not for a spot that gets hosed down. Operating range is about -20 C to +55 C.
• Size and weight: 56 x 77 x 36 mm and 55 g without batteries, per the German inside-digital test.
• Power: two AA alkaline cells, per the manual as quoted in reader comments, with Bosch suggesting Panasonic eneloop pro if you use rechargeables. Battery life is quoted as "under 2 years" in those comments and as 2 years by one retailer. One French retailer claims 5 years, which I'd ignore.
• Mounting: screws or adhesive, on a wall, in a corner or freestanding.
• Other sensors: temperature, brightness and vibration (tamper) sensing.

Zigbee or Thread, and what you lose

There is no separate Matter model. You pick the mode when you set it up, and you can switch later. On Zigbee through a Bosch Smart Home Controller you get everything. On Thread into a Matter system, you need a Thread border router, and only the motion and light functions come through: temperature and brightness aren't passed to Matter, according to inside-digital and matter-smarthome.de. The CSA lists it as Matter 1.2 with Thread and Bluetooth transports. iphone-ticker.de reports it as compatible with Apple Home via Matter. Whether the built-in light can be controlled over Matter is something I couldn't confirm.

For Home Assistant, the Matter route is the obvious one. A Zigbee coordinator of your own would be a second option, but I haven't verified that this sensor pairs outside the Bosch controller, so check before buying it for that purpose.

Where it fits

Garage doors, side passages, hallways and porches. The light turns a plain motion sensor into something that also lights the way, which is the reason to pick it over a bare PIR sensor. Pair it with the usual motion detection automations: lights on at night, notifications when the alarm is armed. With a 2 m mounting height and a pet filter set for animals under 80 cm, a large dog may still trigger it, so walk-test the coverage after mounting.

Verdict

At about 50 euros it's priced like a premium PIR sensor, and you pay for the light and the weatherproofing. It's the better fit if you already run Bosch Smart Home, or want a Thread sensor that does one job well. It's less convincing as a pure Matter sensor, because in Thread mode half the sensors are unavailable. Availability beyond Germany is something I couldn't confirm, and I found no US price. Check the Thread network setup guide before adding it to a Matter home.

Choosing between Zigbee and Thread

This is the real decision with this sensor. If you already run a Bosch Smart Home Controller, Zigbee mode gives you the full feature set, including the temperature and brightness readings and the vibration tamper sensor. If you run Apple Home, Google Home or Home Assistant on Matter, Thread mode gets you motion and the light, and not much else. Bosch's pages say you can switch between the modes later, so the choice isn't permanent.

A Thread battery sensor also leans on your Thread network. It needs a border router in range, such as an Apple TV 4K or a HomePod mini, and Thread works best with plenty of mains-powered routers around it. In a house with a single border router in the living room, a garage sensor at the far end may be a weak link. That's general Thread behaviour rather than something specific to this unit.

Why the detection range is only half the story

Thirteen meters sounds precise, but a passive infrared sensor responds to heat moving across its field of view, not to distance as such. It sees a person walking across the beam far better than one walking straight at it. Mount it at about 2 meters, as Bosch recommends, and angle it so that visitors cross the detection area. Then walk-test it. A precise detection range on the spec sheet and a good result in your hallway are two different things.

The EN Grade 2 rating is worth a sentence. It's the European alarm-industry grade for low to medium risk, which tells you Bosch tested it as a security component and not only as a lighting gadget. It doesn't make it a substitute for a full alarm system.

Sources checked: CSA product listing, matter-smarthome.de, iphone-ticker.de, inside-digital.de, tink.de.