Outdoor monitor temperature thrown off by ESP32 heat

Components
#1

I recently got one of the new outdoor airgradient monitors. I’m very happy with it, except there seems to be a design flaw; the heat produced by the ESP32 appears to affect the temperature sensor when the outdoor ambient temperature is low.

I already had another outdoor sensor, and I mounted my airgradient next to it. When outdoor ambient temperature is above ~64F they read nearly identical values. However, when the temperature falls, the airgradient starts reading significantly warmer; last night it got down to 45F (as reported by my old sensor, and my car, and the other weather stations in my neighborhood) but the airgradient was reporting 52F, which is quite a large divergence from the true temperature.

#2

Yes we are seeing the same effect. It seems to be a linear relationship. So we will most likely be able to come up with an easy compensation algorithm.

#3

Screenshot from 2023-12-25 17-01-54
Screenshot from 2023-12-25 17-01-541964×1101 135 KB

This shows the kind of discrepancy: both the “Living Room” and outdoor sensors are on a table outside and have been there for 45 minutes. The outdoor unit is reading several degrees warmer than the “Living Room” indoor one.

#4

Yes we are working on it and just published a blog post on the process. Basically we are collecting more data to fine tune the algorithm but there is already a ‘pilot’ algorithm in that blog post.

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AirGradient One Temp Accuracy
#5

Worth mentioning that ESPHome has ways to calibrate readings with either linear or polynomial functions if you provide some measurements and their “truth” values so you don’t have to come up with the equations, just the redence points and it will fit them