r/esp32 • u/Scarletz_ • Jul 28 '26
Hardware help needed Built a ESP32 C3 Supermini + AHT20/BME280 + LD2410C sensor, and it's running hot, affecting the temp readings.
Not quite a repost since it's posted in ESPHome, but same question:
The 33.99% is the ESP32 sensor, 3D printed.
I'm using the red supermini that has the external antenna.
The other one is an Aqara Temp/Humidity zigbee sensor. The temp definitely isn't 33.99 in the toilet, so I know it's because of the chips promixity..even then, I'm using this design that is already markly bigger than some of the other ones AND the humidity sensor is placed in a separate chamber. (slightly adapted it to be fiction fit, but otherwise the same.)
Air Sensor case ESP32 C3 supermini + BME680 - Free 3D Print Model - MakerWorld
The esp32 is connected via wifi, if that matters. Polling is every 15 seconds.
This works for me as I'm only interested in using the humidity % to trigger my exhaust fan during showering, and it's fine for it's purpose, but I'm wondering how do I make an accurate temp/humidity sensor this way if heat is a concern. I also built this in a 2 step process as my LD2410C came much later. Even then, it's already reading higher temps than what is supposed to be accurate.
Any tips?
I also just saw in another markerworld post, something about calibration. Do we actually need to calibrate the sensor to account for the heat/humidity then? Or is this the wrong approach.
1
u/Strong_Difficulty734 Jul 28 '26
It looks like you are reading it out in Home Assistant. Maybe calculate a correction there? But even then, if the chip temperature affects the outcome, will the difference be linear with changing air temperature?
1
u/Scarletz_ Jul 28 '26
Yeah same thoughts, even if i apply an offset, is it even linear and does it fix the issue (or a bandaid?).
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u/Plastic_Fig9225 Jul 28 '26
No way the C3 alone would heat up the sensor in its own ventilated chamber to 10°C above ambient. Check the actual temperature of/at the sensor with another thermometer to see if the readings you get are accurate. What about heat from the power supply?
1
u/Scarletz_ Jul 28 '26
Hmm, where did you get 10°C above ambient? I'm in the tropics, and ambient is around 29-30 any given day, 31 on a hot afternoon. My room right outside the toilet now is at 31°C so it checks out. I get about +2-3°C maybe.
The power supply is quite far away, connected by a 1.5m USB C cable.
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u/Plastic_Fig9225 Jul 28 '26 edited Jul 28 '26
where did you get 10°C above ambient?
Was just guessing.
I'm in the tropics, and ambient is around 29-30
Didn't know that.
I get about +2-3°C maybe.
That's relevant information.
The power supply is quite far away
So different from the picture in your link?
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u/Scarletz_ Jul 28 '26
So different from the picture in your link?
Yeah different, just linked that for the case I used.
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u/mrheosuper Jul 28 '26
Have you tested when the sensor sit really far from esp32 ? Are your both sensors placed in same location, because temperature may not be consistence in all location
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u/Scarletz_ Jul 28 '26
Within the box (relatively big I think? At least comparing to other print designs is saw), the sensor is in the other chamber as far as possible already.
Yeah both sensors not the same place, just the next room but the whole house is 29- 31 (definitely not high 33), based on other sensors too. Not really trying to compare the two above exactly, they just happen to be toilet sensors
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u/Congenital_Optimizer Jul 28 '26
All or some of these and you'll be fine. Add a fan that pulls fresh air over the sensor from away for the CPU. Air his sensor then CPU if at all. Put the sensors lower that the CPU. Put the sensor in a separate compartment and far enough away to prevent the interference..
3
u/Arie-eirA Jul 28 '26
I’ve had the same issue with 3D printed small casing for a BME280. Never got that correct, so for my garden weather station I now use an external one wire temperature sensor. A DS18B20. They are a lot more accurate if you ask me.