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BeFlE / SoMoSe

Soil Moisture Sensor
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Questionable Moisture Values #25

Open tps42 opened 4 months ago

tps42 commented 4 months ago

I am currently experimenting witch 2 SoMoSe Sensors (v2.2). I callibrated them (put in glass of water = 100%, in air=0%). When i put them in a very wet plant pot i see strange values. Sometimes i get a reading of about 25% - sometimes i get a reading of about 10% - none of them seem to correllate strongly to the real moisture as i can water the plant w/o noticeable change in readings. Sometimes i can even see a dropdown of the values while i feed in the sensor in the soaking wet pot.

Addition: as i just pulled out both sensors i still get Values of 30% (raw: 1100) for one of the sensors in pure air... had to dry it completely to get realistic value (the second one shows 0% (raw: 150) after pulling out...)

Any ideas? Electromagnetic interference? (LED light installed) "Wrong" soil? Defect sensor(s)?

Thanx in advance!

riegera2412 commented 3 months ago

It is more likely the calibration. While many users calibrate using dry air and pure water this modus operandi for calibration is just wrong!

It would be better to calibrate the sensor in dry and saturated soil. This way the dielectric properties of the soil will be taken into account during calibration. Also, soil in one pot might be different from another. There are different types of soil recommended for different plants, so it is best to calibrate the sensor for each plant individually.

André

tps42 commented 3 months ago

sounds reasonable as you say it.... only the factory default triggered me to use the water-air-method. the defaults will be far far away when callibrating with wet and dry soil. using air and water it was only "a bit off" - i did not believe the factory defauts were so senseless...

Am 30.08.2024 09:26 schrieb riegera2412 @.***>: It is more likely the calibration. While many users calibrate using dry air and pure water this modus operandi for calibration is just wrong! It would be better to calibrate the sensor in dry and saturated soil. This way the dielectric properties of the soil will be taken into account during calibration. Also, soil in one pot might be different from another. There are different types of soil recommended for different plants, so it is best to calibrate the sensor for each plant individually. André

tps42 commented 3 months ago

the maximum raw value i can measure in soaking wet soil is about 800 with a variance of +- 200... this seems to be relatively small value compared to defaults and not very precise... what max raw values du you get in wet soil?

Am 30.08.2024 09:26 schrieb riegera2412 @.***>: It is more likely the calibration. While many users calibrate using dry air and pure water this modus operandi for calibration is just wrong! It would be better to calibrate the sensor in dry and saturated soil. This way the dielectric properties of the soil will be taken into account during calibration. Also, soil in one pot might be different from another. There are different types of soil recommended for different plants, so it is best to calibrate the sensor for each plant individually. André

tps42 commented 2 months ago

Ok... got my issue tracked down (callibrating in wet and dry soil did not solve the problem): It seems the sensors simply dont work at all in my environment! I use a dimmable LED (150W) in 0,7m distance from the sensor. Whenever the light turns on moisture values go up by about 25%... You can see values of a week in attached image (blue moisture, red temperature, light turning on at 7 am an off on 11 pm - watering on Monday and Thursday) - values are totally senseless.

any ideas? moist56-week