HomeHome AutomationAre new Sonoff ZigBee sensors better?

Are new Sonoff ZigBee sensors better?

The release of Sonoff Elite brought some design changes. ITEAD’s products feel more modern, attractive, and yet remain competitive in price. I praised the original Sonoff ZB sensor series for hitting a sweet spot between price, accuracy and battery life, but the design always felt a bit dated. Fortunately, they were easy to hide. Today, I’m pleased to play with a new take on the Sonoff ZigBee series and test Sonoff ZB Button (SNZB-01P) and Sonoff ZB Humidity and Temperature (SNZB-02P) sensor.

What’s new

At first, the new sensors felt bulky in my hand. The first thing I did was to compare the new Sonoff ZB Sensors with the old ones. Surprisingly, their new designs are only slightly thicker than the previous generation. The new design feels fresh, and the inclusion of the metallic mounting plates (3M tape/screws) opens up new opportunities to mount it.

The battery inside these sensors has changed too. It’s still a 3V coin cell, but much thicker. The previous batch already used a bigger CR2450 to power the sensors for longer – the new revision brings a monstrous CR2477 1100mAh cell that will last up to 4 years.

On the inside

A quick peek inside reveals a change in the IC responsible for ZigBee 3.0 communication. The EFR32 MG22C22 has superseded the CC2530 IC of the previous generation. The sensor is more compatible and can be linked directly to other hubs, including Amazon Echo Hub (ZigBee enabled) and SmartThings.

I was not able to determine the sensor ID, but it does resemble the one used before (091R). The product page lists STH40 as the sensor inside.

ZigBee hubs…

If you don’t have a hub just yet, there are options! You could pick Sonoff ZB Bridge Pro and run your sensors in the eWeLink app or flash it with custom firmware and run it alongside NodeRED or Home Assistant. If you want to be fancier, check out iHost – a new take on smart hubs from ITEAD that comes with NodeRED and support for docker images. You could also dive into custom coordinators and pick Sonoff ZB Dongle Plus or Electrolama.

The new sensors from Sonoff use ZigBee 3.0 and will also be compatible with Amazon Echo Hub or SmartThings. You are spoiled for choice.

Sonoff ZB Button (SNZB-01P) $9.90

Other than shape and included six labels to customise your Sonoff ZB Button not much has changed. The button is responsive and offers 3 actions: single press, double press and long press. These are the same actions that were available before on Sonoff SNZB-01 Button.

As the button is only $2 more expensive, paying extra for a more modern design, labels including (home, sleep, light, bell, power, SOS) and extended battery life feels like a good deal so – grab your SNZB-01P now!

Sonoff ZB Humidity and Temperature (SNZB-02P) $10.90

There are still two metrics available: humidity and temperature. The mounting plate will come in handy, especially since you can’t use the square shape of the enclosure to prevent it from rolling. I used to put my Sonoff SNZB-02 on top of door frames and paintings.

The reporting rate seems to be similar to the previous generation. SNZB-02P has reported every 25min with more frequent updates on sudden temperature or humidity changes. Blowing on the sensor triggers an instant update.

Is it more accurate?

In an attempt to compare the new Sonoff SNZB-02P to the older design (SNZB-02), I placed both side by side. As the eWeLink app still records hourly intervals, I hooked it up to my NodeRED and Sonoff ZB Dongle Plus and let them run for a while.

That’s 2 sensor graph!

As you can see from the attached screenshot, temperature reads are identical. How do they stack against other ZigBee sensors? Take a look at this article, which compares 11 temperature and humidity sensors and look at the SNZB-02’s performance since they are identical.

Where things get slightly confusing is the humidity. The old Sonoff sensor overreports it by 11% consistently. I verified this with the Aqara TVOC sensor, which backs the readout from the new Sonoff SNZB-02P. Even though readings are higher on the older sensor, the relative change in humidity is still on point. Once I calibrated the sensor in the ZigBee2MQTT dashboard, the results were identical once again.

Calibration

Some of you asked how to calibrate this. There are 2 things to keep in mind. If your sensor reports correctly the relative changes, you can use the ZigBee2MQTT dashboard to enter the humidity offset.

This will put the reading in the range of what should be expected from the sensor. This was my case, as the sensor in question was reporting changes correctly.

If however your humidity sensor is saturated, you will need to make sure there is no water ingress and bake the sensor in about 100C for 2h. This will remove the residue moisture. It’s advisable to expose it to 75% humidity for 12 hours before using it again.

The new SNZB-02P costs just over $2 more, but the extended battery could be worth it. It gives you peace of mind.

Shop with Sonoff

Take a look at the ZigBee and WiFi range of the devices compatible with eWeLink:

Final thoughts

It’s fair to expect that the contact sensor (SNZB-04) and motion sensor (SNZB-03) will follow suit. The question is when? The current design is tempting and with the battery poised to last years, it’s hard to argue against these. Got questions? Feel free to ask in this Reddit thread.

🆓📈 – See the transparency note for details.

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