SONOFF SNZB-02D review - A Zigbee temperature & humidity sensor with a 2.5-inch display

We’ve previously tested the SNZB-02 Zigbee temperature and humidity sensor with the SONOFF NSPanel Pro smart panel, but ITEAD has now launched the SONOFF SNZB-02D that integrated the same features plus a 2.5-inch display to visualize the data.

They’ve sent us a SNZB-02 sample for review, so after listing the specifications we’ll test SONOFF’s latest Zigbee sensor with Home Assistant.

SONOFF SNZB-02D specifications

Display – 2.5-inch black&white display
Connectivity – Zigbee 3.0
Sensors
- Temperature sensor with -9.9°C to 60°C range, ±0.2°C accuracy
- Humidity sensor with 5%—95%RH range, ±2%RH accuracy
Battery – 3V CR2450 coin-cell battery good for about 2 years with a 5-second polling rate
Dimensions – 62.5 x 59.5 x 18.5mm
Material – PC
Color: White

Unboxing and first try

We’ll find the sensor in the usual orange package used for Zigbee devices. The SNZB-02D sensor comes with a quick start guide and a pre-installed battery. Just pull the plastic sheet out of the device and you’ll find the device ready to use right away. The display also comes with a plastic film to prevent scratches that you can keep or remove. The package also includes a magnetic mounting bracket which comes with a thin 3M double-sided adhesive for mounting on the wall.

Alternatively, the mounting bracket comes with a stand that can be unfolded to be placed on a flat surface such as a desk or a coffee table. So far so good.

The SNZB-02D Zigbee sensor relies on a CR2450 coin-cell battery for power. It’s a widely used battery that can be easily found in supermarkets or online. We point out this due to previous experiences having difficulties finding batteries for some Smart Home products from other brands.

The hardware is based on the popular Silicon Labs (SiLabs) EFR32MG22 Zigbee microcontroller known for its high energy efficiency, as well as the Sensirion SH60 AD1AFU temperature and humidity sensor.

The display interface is quite simple and easy to read. There will be temperature and humidity values displayed at the top and bottom of the screen respectively, and we can switch the temperature display unit from Celsius to Fahrenheit by just pressing the button on the back of the display 3 times. The battery level is also shown at the very top of the screen.

Pairing the SNZB-02D sensor with a Zigbee coordinator in Home Assistant

The manual explains how to get started with the Sonoff Zigbee Bridge in the Quick Start Guide, but in this review, we will be using the Sonoff Dongle-P acting as a Zigbee Coordinator through the Home Assistant framework with integration provided via the popular Zigbee2MQTT add-on. Pairing the device with the Coordinator is easy, and that were no issues or conflicts at all. You can press and hold the button behind the sensor for about 5 seconds, then the screen will show a blinking Wireless symbol, meaning it is currently pairing, and the symbol will disappear when pairing is completed.

The sensor then sends us 4 Entities: temperature, humidity, battery level, and signal strength.

Field testing, SONOFF SNBZ-02D comparison against Xiaomi LYWSD02

For real-world testing, the SONOFF SNZB-02 sensor was then installed in a location where another weather monitoring station is installed, namely the Xiaomi LYWSD02 using BLE for communication.

After 3 days of measurements, we could conclude that the SNZB-02D sensor provides quite accurate readings for both temperature and humidity. The charts below show the temperature and humidity data for the SNZB-02D (blue line) and the LYWSD02 (purple line), and we can be satisfied with the results.

There were some differences between the two devices, and both may need to be calibrated again. You can calibrate the SNZB-02D from the Zigbee2MQTT interface as shown below.

We also quickly tested ZHA (Zigbee Home Automation) integration and we had no problems pairing the device and taking measurements for about half a day.

Conclusion

The SONOFF SNZB-02D can be considered a good option among other temperature and humidity sensors with built-in displays available on the market since the 2.5-inch is adequately sized for this type of application and the sensor works well and accurately. Having said that, some may have preferred a display with a wider viewing angle and less flickering, but overall the quality of the LCD screen is still good.

The latest SONOFF device can be installed in various ways either integrated into your furniture, wall mounted, or simply placed on a table or desk. The SNZB-02D is impressive in terms of data transmission, compared to other sensors in the same segment, even though Zigbee has limitations in terms of design for energy efficiency. Nonetheless, the connection was stable, working well consistently, and the temperature and humidity values closely matches the ones of a competing sensor installed in the same location. This makes the SNZB-02D another recommended option for users to try out.

We’d like to thank ITEAD for providing the SONOFF SNZB-02D Zigbee LCD smart temperature & humidity sensor for review. It can be purchased for $12.99, and coupon CNXSOFTSONOFF should add a further 10% discount to any order on the SONOFF store. Users from the US may also buy it on Ameridroid for $11.69 plus shipping and tax using the same coupon.

This review is a translation, with some edits, of the original post in Thai language by Damrongwit Nusuk on CNX Software Thailand.

Jean-Luc Aufranc (CNXSoft)

Jean-Luc started CNX Software in 2010 as a part-time endeavor, before quitting his job as a software engineering manager, and starting to write daily news, and reviews full time later in 2011.