Air Gradient Outdoor temperature tolerances

Components
#1

Hello

I have 3 outdoor Air Gradient kits - 1 Model O-1PST and 2 Model O-1PPP. These units all use the PMS5003T sensor for temperature monitoring.

It was pretty cold where I am last night - getting down to nearly -10°C. Looking at the history of all the units they started to mis-report temperatures. Here’s a snippet of the logs of one of the 1PP units that has 2 PMS5003T units in:

[07:38:45][D][sensor:094]: ‘Temperature (1)’: Sending state 6552.89990 °C with 1 decimals of accuracy

[07:39:28][D][sensor:094]: ‘Temperature (2)’: Sending state 6553.20020 °C with 1 decimals of accuracy

Here’s one of the other 1PPP units reporting:

[08:17:36][D][sensor:094]: ‘Temperature (2)’: Sending state 0.00000 °C with 1 decimals of accuracy

[08:18:07][D][sensor:094]: ‘Temperature (1)’: Sending state 6553.39990 °C with 1 decimals of accuracy

and the PST unit:

[08:19:31][D][sensor:094]: ‘Temperature’: Sending state 6552.50000 °C with 1 decimals of accuracy

My tempest weather station (different hardware) is currently reporting the temperature as -8.2 °C at the time the logs above were taken. I’m assuming it Is too cold for the Air Gradient units to report temperature? What’s the expected lowest temperature they can record? I’m running the units via ESPHome so I could potentially put some lambda logic to report the lowest possible temperature, instead of 6500°C!

#2

Hah, you are right. I wonder if this is a ESPHome bug or just below the minimum supported by the PMS5003T. I couldn’t find a datasheet for it right away, but I’m getting silly numbers through ESPHome/HomeAssistant as well. It is around 3F right now.

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#3

See the previous thread where this was discussed: Operating temperature of the outdoor unit? - #21 by Achim_AirGradient

#4

This is slightly different, where it is more than just being off by a few degrees. It looks like a signed vs unsigned integer type issue, as it sure doesn’t feel like 11,817F outside…

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#5

There was an issue open for it and a PR got merged in 3 days ago, so we’ll see the fix in a few weeks

Incorrect readout for negative values for PMS5003T · Issue #3814 · esphome/issues (github.com)

#6

@MallocArray Thanks for finding that PR link.

I have a similar setup to you - using these devices via ESPHome into Home Assistant.

#7

The temperature sensor inside the PMS5003T has a range of -40 to +100 degrees Celcius. I double checked it with the manufacturer.

I don’t see any of these very high values so far with the stock firmware. It could indeed be something ESPHome related.

#8

Thanks @Achim_AirGradient it does look to be an ESPHome issue with how the values are stored. The linked PR suggests it’s fixed in the dev branch. Thanks everyone!

AirGradient Open Air Returning high temprature with ESPHome
#9

I’ve asked on the ESPHome Discord to see if the fix for this can be included in 2023.12.9, as it appears there won’t be a 2024.1.0 release made from the dev branch so the fix wouldn’t otherwise be available until some time in February.

For now, if @MallocArray wants to do so, their ESPHome configs can be changed to pull the PMS5003 component from the ESPHome ‘dev’ branch since it has the fix.

#10

It looks like the fix has been included in 2023.12.9 available today:

image

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