Sonoff SNZB-02P temperature sensors often unavailable

[Kristen (Kris)]

I’m relatively new to this, so may have a schoolboy error. I’m a database software programmer, so I have skills in that area.

I have a number of Sonoff SNZB-02P temperature / humidity sensors scattered around the house (and a couple of smart plugs to help extend Zigbee range)

One of them seems to toggle available / unavailable on a relatively long period. ChatGPT suggests it might have a SLEEP or battery-saving setting (I’m not aware that I have fiddled with any settings).

Others seems to register temperature reliably, varying through the day as I would expect, and then suddenly stop doing that (my assumption is that they become “unavailable”), and then start providing data again.

I found a few topics about this, but not many, and no obvious solutions. Comments tended to be “They are cheap” rather than anything concrete.

If this is the “norm” I would have expected to see more posts about it - presumably folk are actually relying on reasonably worthwhile temperature data to control things?

I need something which will reliably provide a temperature reading “regularly”. House temperature changes slowly, so “instant reporting” not required, per se.

Is this “unreliability” common for this type of sensors?

Can I spend-more-money and guarantee a better solution?

Or some other approach to improve robustness? Lots (how many is that?) or Zigbee repeaters maybe?

One approach I have spent a bit of time on is to try to use a program to detect any toggle between “Available/Unavailable”, in order to see when this happens. My thinking is that the graphs in HA are not a good indicator, because they seem to maintain temperature-assumption after the device becomes unavailable, I would like data to “not exist” and “No assumption made” when a device is unavailable - so that at least I could see when that was happening.

[Kristen (Kris)]

Some threads I’ve looked at:

ZHA SNZB-02P unavailable for 6 hours every 6 hours

Hello, I’m relatively new to Home Assistant and smart home in general. I’ve got 3 SNZB-02P Sonoff ZigBee Temperature & Humidity Sensor. They’ve been working fine for some weeks since installation but recently one of them has started dropping out every 6 hours and stays unavailable for about 6 hours before coming back. I’ve been searching and trying to find a solution or explanation as to why this is happening but haven’t found anything that provides a solution. I’ve recently noticed by look…

SONOFF Model SNZB-02D updates humidity but not temperature

I have two Sonoff SNZB-02D Temperature and Humidity sensors. I seem to have a weird issue where the humidity is updating frequently but the temperature updates only rarely. The display on the device updates immediately but only the new humidity values are reported to zigbee2mqtt frequently. I don’t thhink it is because of signal interference since device is able to communicate the humidity values to zigbee2mqtt. Is this a know issue? Does anyone know how to fix it?

Sonoff SNZB-02 Temperature sensor looses connection after a while

Hi, I am using the latest Home Assistant OS Raspberry image in combination with Sonoff SNZB-02 temperature sensor. After installing the OS the sensor is immediately recognized and sends regulary updates of temperature and humidity. However, after a while, the values do not update anymore and the quality of the link shows zero. The position and the total setup of other devices is still the same. Repairing does not fix the problem. The battery is still ok. Removing the battery and repairing also d…

[Kristen (Kris)]

Example of several sensors

Orange - reasonably reliable, but was goofy around 15-Apr

Dark blue - drops in and out at regular intervals (and I don’t trust the “straight line” bit

Pink - started off OK … absent for several days, suddenly resumed

Yellow - starts off OK, now showing constant temperature (I am presuming that the actual is “Unavailable”)

Green - mostly good, some daps, some obvious “flat line” untrustworthy sections too

Purple - a gap on 15-Apr, but I don’t believe temperature does not change at all!

And a higher-res if needed

[MangoCats]

I just installed a SNZB-02P and it was very intermittent until I bent the battery contact springs to make better contact.

I also had intermittent reporting after fixing the battery contact issue which for me was due to the 02P stubbornly attaching to a far away router. By repairing with the ZHA set to pair with a specific router that fixed it.

Until I did a firmware update, then it ran back to a far router, but it is staying put again after another directed repair.

[Didgeridrew]

@Kristen

and a couple of smart plugs to help extend Zigbee range

What do you mean by “a couple”?

When it comes to Zigbee, you want to have at absolute, bare minimum one router in each room and one in each hallway… and if you have small rooms and/or dense walls you may need 2x or more than that to get a decent mesh.

[Kristen (Kris)]

@Didgeridrew

What do you mean by “a couple”?

So far just 2. My system/sensors are experimental (prior to distributing around the house)

One smart plug is near the Raspberry Pi, and the other is near the Sensors that I have placed remotely

All the sensors that are “close” are in one of three open-plan areas (close to Raspberry Pi and the Smart Plug that is nearby)

The “remote” ones are grouped in two rooms with clear line of site (door always open) to the smart plug.

I’ve tried the most erratic (“Bay Temperature”) sensor in several places around that room, currently it is actually sat on top of the Smart Plug (about 2M away from the Raspberry Pi)

The furthest away is the “Outdoor” sensor - that is a couple of rooms from nearest smart plug and, additionally, is outside (Cavity block/brick wall in the way)

So I specifically have to PAIR each sensor with the nearest Smart Plug “repeater”, or should it figure that out for itself? (I saw that @MangoCats specifically did that, but should it be unnecessary?)

[Kristen (Kris)]

More recent graph. For the last couple of days the more reliable ones have been working OK, but were erratic a few days before that. I can’t think of anything that has changed; I have been away and thus I haven’t pressed “reset” button or anything like that

[Didgeridrew]

@Kristen

So far just 2. My system/sensors are experimental (prior to distributing around the house)

That’s a mistake a lot of people (including me) make when they are starting out with Zigbee. Any experimenting you do with a overly-sparse mesh won’t be reflective of what will happen with a proper mesh.

@Kristen

So I specifically have to PAIR each sensor with the nearest Smart Plug “repeater”, or should it figure that out for itself? (I saw that @MangoCats specifically did that, but should it be unnecessary?)

You can try specifically pairing end devices with routers, but the mesh will change routing based on it’s own internal logic. It’s usually best to just place the device where you want it and then add it to the mesh.

[MangoCats]

I specifically have to PAIR each sensor with the nearest Smart Plug “repeater”, or should it figure that out for itself?

It should figure that out for itself.

In the description of your setup, I would question how well your two routers reach each other. If you’re really going to “do Zigbee” you probably should go ahead and get a few more routers (like smart outlets) to go in the middle of the two you have, if none are more than 3-4 meters away from the closest you should be in great shape.