A small sensor with a longer-life pitch
Xiaomi has launched its Door and Window Sensor 3 on the Xiaomi Youpin crowdfunding platform in China. The campaign runs from October 12 at 10 a.m. until October 19 at 10 a.m. local time. The crowdfunding price is 44 yuan, while the suggested retail price is 49 yuan.
The device detects whether a door, window, drawer or cabinet is open or closed. It is described as small and thin enough to fit on narrow edges, with markings that help users line up the sensor and its magnet.
One hardware change is a tunnel magnetoresistance sensor, shortened to TMR. Think of it as the part that notices when the nearby magnet moves away or returns. It replaces the Hall sensor used in Xiaomi’s previous model.
Xiaomi says the TMR sensor uses less power. The company claims Sensor 3 can run for up to three years on one CR2032 coin battery—three times the roughly one-year battery life attributed to Sensor 2. The Mi Home app can also warn users when the battery is running low.
The three-year figure comes with conditions
Three years isn’t an unconditional promise. Xiaomi’s test scenario assumes 30 openings and 30 closings each day, adding up to 60 events.
The launch information doesn’t say how heavier or lighter use would affect battery life. There is also no independent long-term testing of battery life, responsiveness or missed events. For now, three years is Xiaomi’s test-based claim, not proven household performance.
Better activity records, but no light sensor
Xiaomi says Sensor 3 can show whether a connected door, window, drawer or cabinet is open or closed. The Mi Home app can display past events, count daily openings and closings, and track how long the monitored object stays in either state.
There is a trade-off. Sensor 3 drops the light sensor included in Sensor 2. People who use the older model for light-based automations may need another compatible sensor, though the launch information doesn’t identify an official replacement.
Remote features need another compatible device
Remote status checks and notifications require a device with Bluetooth Mesh gateway functionality. A gateway works like a bridge: it carries the sensor’s updates into Xiaomi’s connected-home system so users can receive them remotely through the Mi Home app.
The launch information doesn’t identify which Xiaomi hubs or routers work with Sensor 3. Its wireless range, Bluetooth version and detailed radio specifications are also unknown.
Xiaomi gives examples such as switching on lights when a door opens or turning off an air conditioner when a window opens. When paired with separately purchased leak or temperature-and-humidity sensors, Sensor 3 can also provide reminders to close a window. These routines must be set up in Mi Home and require compatible devices.
Availability and privacy questions remain
All confirmed prices and launch details apply to China. Launch plans, dates and prices for Europe, North America and other regions haven’t been established.
Support for Apple HomeKit, Amazon Alexa and Google Home is also undocumented. Launch coverage describes integration with Xiaomi’s Mi Home, Surge Smart Connect and HyperOS Connect systems, leaving compatibility outside that ecosystem unknown.
Mi Home can display a history of opening and closing events, but the available information doesn’t explain exactly how Sensor 3’s logs are stored, encrypted or retained. That doesn’t mean the data is handled improperly. It means the device-specific details needed to judge its privacy practices aren’t available.
How this was reported
- Strongest primary sources: No primary Sensor 3 document in the reporting material established a major launch claim.
- Important independent sources: iXBT and SmartWorld provided independent launch coverage and details about the generational changes.
- Major unresolved facts: Actual long-term battery life, gateway-model compatibility, international availability, third-party platform support and device-specific privacy practices remain unknown.
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