New Goodies from SwitchBot – Indoor/Outdoor Thermo-Hygrometer

I’ve recently grabbed a couple of these new sensors from Switchbot and they come complete with two AAA batteries pre-fitted. The back comes off easily for replacement, no tools required. Model is W3400010. Don’t ask why the box is so dirty – no idea.

Once set up in the Switchbot APP (in my case on Android), the new sensor by default is called “Outdoor Meter 7A) with a claimed battery life of 1 year.

Not a lot to say about these outdoor units – they come with a lanyard so you can hang them up — and they work as you’ll see in the photos. I’ve also added them to Google Home so they appear in my Google Home App.

For clarification, to read these externally you need one of the Switchbot Hubs (the Mini or Hub2) but none of that is needed for internal use only.

I have a Switchbot Hub2 covered elsewhere and which also doubles up as an internal temperature/humidity display and would also intergate all my IR remotes into one – exepct that is hasn’r occurred to Switchbot that IR is only one mechnism for remotes – in reality my TV box remote is WiFi, the TV is infra-red and the TV Sound Bar is Bluetooth) and recently bought a Google Nest Mini for my office – as you’ll see elsewhere I’m trying to get everything working with MATTER – the up and coming integration standard.

SwitchBot Indoor/Outdoor Thermo-Hygrometer

It’s going to be some time before I can verify battery life – as you can see the sensor has been running for just a few days… (as the termperature goes up, the humidity plummets).

Ok, next question – without setting anything up, can I say to Google Home “Hey Google, ask Switchbot to tell me the temperature of outdoor meter 7A” – yes, I can – that’s a plus.

Update: At last check (June 4, 2023 11:19) the little outdoor decice has been running for a week – battery still says 100% and has recorded 9935 events… time to give it a permanent job outside. Let’s see how waterproof it is.

Device Positioning

I’ve discussed this next bit many times with friends but thinking about it, never written this down despite testing and reviewing temperature/humidity sensor from all the major players. To many of you, what I’m about to say will seem blindingly obvious – but trust me, it’s not obvious to everyone. Place the sensor away from direct sunlight and extremes of weather in general yet with access to fresh air.

Obvious? Well, when I first started visiting Spain I recall on one return to the UK, one not-too-bright fellow in the village emailing me, knowing I was back in the freezing cold wastes of the Northeast of England in winter, to tell me that it was 35c in Spain that afternoon. I asked him how he arrived at that figure. “Garden sensor” he replied, referring to a sensor mounted on a post in his garden, with direct contact with the blisteringly hot sunshine of the time. WRONG.

This will vary from place to place but for example, in Andalusia we get summer temperatures of up to 40c – air temperature in the shade – as it shoud be, but people still point me to sensors they mount on the dash in their cars or on the windscreen – of course seriously affected by cumulative sunlight trapped inside a parked vehicle with closed doors and windows. That is NOT how you measure temperature.

Also your typical humidity sensor needs access to subdued airflow, again protected from direct sunlight but also protected from driving rain and wind which with the best will in the world, will eventually get through almost any cheap plastic seal.

So – my sensors…. I have in a window that protects from most (but not all) direct sunlight and which protects anything on it from the most severe rain, an Aqara TVOC sensor (temperature, humidity, air quality). I have as I write this however noted that the TVOC sensor is giving somewhat elevated temperature sensors compared to those completely in the shade in our pergola.

Aqara TVOC sensor

Next, under our not 100% waterproof pergola, a simple display-less Zigbee Aqara temperature/humidity sensor is currently claiming 23.8c and 47% humidity .

Sonoff sensor

and now, a couple of metres away, again sheltered from direct rain and direct sunlight but again otherwise open to the atmosphere, the new Switchbot sensor – the subject of this article.

Rather than use the supplied carry-cord, I simply used double sided adhesive foam on the back so I SHOULD be able to easily pull away the body to replace the two AAA batteries when the time comes.

I put the sensor outside half an hour ago (in the open-on-two-sides pergola) and now according to my phone which is inside the house, in my office – “Your device has disconnected from your hub”. The small, white (and particularly unstable on the bench) Switchbot HUB is in also my office. Oh, well.

OH, spoke too soon, 30 seconds later – a reading…. but then the same message again… I’m guessing the sensor is connecting to the HUB by Bluetooth – never a good idea here with stone walls, I have the same issue with a garden moisture sensor.

Devices driven by WiFi are generally OK as I have a WiFi access point in a box in the pergola. However, I’ve just checked again – last reading 12:39, just a minute ago – so it’s working fine.

Note that the unit is recording temperature, humidity and pressure.

It is time like this that make me think – why is that TVOC sensor showing higher temperature – I know why it’s showing lower humidity – it rained last night and the TVOC sensor is in the path of more airflow – but I am going to have to rethink that lopcation slightly. The Switchbot pergola sensor however correlates closely with the nearby Aqara pergola sensor – happy with that. The rest is down to battery life – I’m using the twin pre-installed cheap-looking AAA Alkaline batteries right now.

What I DON’T understand is why the Switchbot APP keeps putting up a RED warning about disconnection which regularly disappears as a new reading comes in only moments later. Note the time on the two images with no errors… above-left and below.. the lower average is because the sensor until this morning has been sitting in my office.

Switchbot internal/external sensor

The Switchbot Hub 2 is covered elsewhere in the blog and is it seems essential for accessing this temperature/humidity sensor remotely. Nice enough but a tad flimsy.

Switchbot Hub 2

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