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Roberto R.

Fibaro Smart Implant with DHT-22 sensor

Question

Hello everyone!

a few days ago I took a smart implant and connected a DHT-22 sensor to it to detect humidity and temperature in a greenhouse.

The Smart implant is powered by a 220-240 V power supply, DC 12V 1.25A, 15W output and is located inside an electrical panel while the sensor is positioned inside the greenhouse.

Please login or register to see this attachment.

Now my problem ... the internal temperature sensor of the smart implant reaches temperatures over 55 ° C even if the air temperature is 30 °.

At midnight tonight the internal sensor measured 35 ° C while the external sensor DHT-22 measured 22 ° C.

This thing seems strange to me also because the operating temperature range reaches max 40 ° C.

In this regard, in fact, the DHT-22 sensor measures the temperature and humidity regularly until the smart implant does not exceed 44 ° C, then flat graph, the DHT-22 stops giving me data.

If I unplug the power and plug it back in for a few minutes then it stops again.

At night, however, everything works perfectly.

What do you think it can be?
Wrong power supply?
Faulty smart implant?

A further test I did was put the smart implant outside the electrical panel, in the open air, the internal sensor still exceeds 47 ° C when in reality it is 30 ° C and the external sensor no longer sends me the data .

Thank you!

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Posted (edited)

Smart Implant does use NTC, which in the supply range 9-24V have some supply voltage based offset (nothing tragic, one change offset on HC),

 

here 12V supply

 

Please login or register to see this image.

/monthly_2020_07/image.png.781bacf42ed9c622ac6464969aa3e2f7.png" />

 

and 24V supply

image.png.42d3f87de9aee6691673964ef3b63591.png

 

Still the value is bit high, PCB was 24.5°, however, again not big deal (as there is offset setting available)

 

I don't have DHT22, so tested with DS18B20, and don't see any issues (both sensors set to report 0.1°, everything else set to default, SI with fw 5.1).

Ignore that one peak down, that was me. Red is exernal, blue internal sensor.

I started first to heat up the PCB to have some visual difference and the "rant condition" you described (when internal higher 45 no data from external).

As you can see, way over 45° and no issues with values from both.

 

image.png.3c8f276d9c2bb00c1d1f6d4f4bdde56f.png

 

However, that's with DS18B20, and not DHT22, so don't take this as measure for usability,

there might be still broken DHT22 or buggy firmware.

Someone with DHT22 need to take similar measurment.

 

EDIT: ohh, i see, you testing second one DHT22. Normally DHT22 should not get destroyed that easy (ESD), i remember as jung student i destroyed two expensive LCD displays^^, since them i'm bit more carefuly. 

Edited by tinman

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Two possibilities that I see:

1. Faulty internal temperature sensor

2. Sensor is working and correctly reporting that the device is overheating

 

Option 2 is my hypothesis. Does the smart implant feel warm?  Can you attach the external probe to the housing so you can measure the implant case temperature? (you will need to thermally couple them together).

 

If the device gets too hot, it may shut down, so that may be why you only see the issue during the day. (I don't like how this device is only rated to 40C, might be ok for Poland but not for Australia, especially if you want to use in a roof cavity).

 

Your power supply is actually a LED driver.  This may be a constant current type and therefore not suitable.  Can you measure the current consumed with a multimeter? Excessive current will translate to heat.  You might even burn out your implant.  Try powering with a 9V battery and see if the overheating issue goes away.

 

Lastly, have you double / triple checked all your wiring?

 

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  • 4 hours ago, Tim__ said:

    Two possibilities that I see:

    1. Faulty internal temperature sensor

    2. Sensor is working and correctly reporting that the device is overheating

     

    Option 2 is my hypothesis. Does the smart implant feel warm?  Can you attach the external probe to the housing so you can measure the implant case temperature? (you will need to thermally couple them together).

     

    If the device gets too hot, it may shut down, so that may be why you only see the issue during the day. (I don't like how this device is only rated to 40C, might be ok for Poland but not for Australia, especially if you want to use in a roof cavity).

     

    Your power supply is actually a LED driver.  This may be a constant current type and therefore not suitable.  Can you measure the current consumed with a multimeter? Excessive current will translate to heat.  You might even burn out your implant.  Try powering with a 9V battery and see if the overheating issue goes away.

     

    Lastly, have you double / triple checked all your wiring?

     

     

    Yes, the power supply feels a little warm, in fact I have already ordered a power supply other than 12V.
    You say it is appropriate to try a 9V power supply?
    What type of power supply do you recommend?
    But if it overheats like this with a 12V power supply what would happen with a 30V power supply?
    Thank you!

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    What I meant was check if the Smart Implant was feeling warm.  You aren't using a power supply but an LED driver, this has different circuitry in it to a power supply.

     

    The smart implant can work on 9V, that's why I suggested temporarily testing on a 9V battery.

     

    A 9 or 12V power supply is fine.

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    12 hours ago, Roberto R. said:

    powered by a 220-240 V power supply, DC 12V 1.25A, 

    Please login or register to see this attachment.

     

     

    this is not power supply, this is LED Driver. Please use proper power supply (no LED driver, no charger, etc.), with filtered output, this is highly recommended to get stable measurments from DHT and Smart Implant.

    • Like 1

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    Posted (edited)

    Why not a completely different approach and use a DIY polution sensor with humidity, temperature, but also PM2.5 and PM10 readings?

     

    The cost for DIY air pollution sensor is less than a Fibaro Smart Implant. 
     

    You only need:

    • Nova SDS011 air pollution sensor
    • NodeMCU ESP8266 V2 or V3 opensource WiFi board
    • And re-use your DHT22 temperature and humidity sensor
    • Power supply

    (You can buy it as a set about 30 euro, or in parts cheaper from AliExpress)

     

    See for QuickApp: 


    Or for Virtual Device:

     


     

     

    Edited by SmartHomeEddy

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  • 4 hours ago, tinman said:

     

    this is not power supply, this is LED Driver. Please use proper power supply (no LED driver, no charger, etc.), with filtered output, this is highly recommended to get stable measurments from DHT and Smart Implant.

     

    In fact, I had doubts about nutrition.
    Tomorrow I get the new one, hopefully everything is solved!
    I took this, is it correct?

    Please login or register to see this link.

     

     

    4 hours ago, SmartHomeEddy said:

    Why not a completely different approach and use a DIY polution sensor with humidity, temperature, but also PM2.5 and PM10 readings?

     

    The cost for DIY air pollution sensor is less than a Fibaro Smart Implant. 
     

    You only need:

    • Nova SDS011 air pollution sensor
    • NodeMCU ESP8266 V2 or V3 opensource WiFi board
    • And re-use your DHT22 temperature and humidity sensor
    • Power supply

    (You can buy it as a set about 30 euro, or in parts cheaper from AliExpress)

     

    See for QuickApp: 


    Or for Virtual Device:

     


     

     

     

    I hadn't even thought about it because I don't care in the greenhouse to know about PM 10 and PM 2.5.
    Now take a look :-)
    Thank you!

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    Posted (edited)

    Your plants 🥬🍅🍆 probably won’t grow faster with good PM2.5 or PM10 readings.

     

    But it is a nice feature for yourself 😷 and the cost is very low. 
     

     

     

     

    Edited by SmartHomeEddy

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  • New power supply.

     

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    11.15 pm external temperature 28 ° C, internal temperature reported by the smart implant positioned outside the electrical panel 35 ° C.
    I think the smart implant is defective.
    I make the return ..

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    Isn't it a known issue that the inner sensor in smart implant shows higher temperature than the real one?

    I have the same problem, so I disabled inner sensor and I'm using only the external one (DHT-22)

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  • 4 hours ago, pogo said:

    Isn't it a known issue that the inner sensor in smart implant shows higher temperature than the real one?

    I have the same problem, so I disabled inner sensor and I'm using only the external one (DHT-22)

     

    I don't know, Fibaro support said it is defective and doing RMA.
    However as soon as the internal sensor exceeds 45 ° C I no longer receive data from the external sensor, this is the main problem, so something is wrong there ..
    Tomorrow I get the replacement one, let's see if anything changes.

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  • Posted (edited)

    Only I have this problem?
    Smart Implant new, same problem.
    When the internal sensor exceeds 40 ° C (for no reason), the external DHT22 stops sending me the data.
    I don't know how to fix it ..
    Maybe I'm wrong?

    Power supply (

    Please login or register to see this link.

     ) ?

    External sensor (

    Please login or register to see this link.

     )?

    Cable length of the external sensor (about 4 meters)?

    Type of connection cable for the external sensor (2.5mm electric cables)?

    Edited by Roberto R.

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    Your parts now all look ok to me. Perhaps try disabling the inside sensor as pogo suggested, and see if that allows you to get a higher temp reading. Otherwise I'm out of ideas. 😐

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  • 18 minutes ago, Tim__ said:

    Your parts now all look ok to me. Perhaps try disabling the inside sensor as pogo suggested, and see if that allows you to get a higher temp reading. Otherwise I'm out of ideas. 😐

    Now I try to replace the sensor dht22 and see if maybe it is defective ... it would be the second defective though, the first was not even going ... are these sensors reliable?

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    I have two DHT-11 for Audrinos. Both of them have accurate temperature readings, but one always reports humidity as above 90%, even when it is not. DHT-22 should be more accurate than DHT-11. It's still possible that you have a defective device.

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  • 2 hours ago, Tim__ said:

    I have two DHT-11 for Audrinos. Both of them have accurate temperature readings, but one always reports humidity as above 90%, even when it is not. DHT-22 should be more accurate than DHT-11. It's still possible that you have a defective device.

    new DHT22 sensor, same situation, data reception stops.
    Now I try to disable the internal sensor, let's see if something changes.

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  • Posted (edited)
    19 minutes ago, tinman said:

    Smart Implant does use NTC, which in the supply range 9-24V have some supply voltage based offset (nothing tragic, one change offset on HC),

     

    here 12V supply

     

    Please login or register to see this link.

     

    and 24V supply

    Please login or register to see this link.

     

    Still the value is bit high, PCB was 24.5°, however, again not big deal (as there is offset setting available)

     

    I don't have DHT22, so tested with DS18B20, and don't see any issues (both sensors set to report 0.1°, everything else set to default, SI with fw 5.1).

    Ignore that one peak down, that was me. Red is exernal, blue internal sensor.

    I started first to heat up the PCB to have some visual difference and the "rant condition" you described (when internal higher 45 no data from external).

    As you can see, way over 45° and no issues with values from both.

     

    Please login or register to see this link.

     

    However, that's with DS18B20, and not DHT22, so don't take this as measure for usability,

    there might be still broken DHT22 or buggy firmware.

    Someone with DHT22 need to take similar measurment.

     

     

     

    Thanks for your test!
    What parameter is the offset?
    I don't see it anywhere ..
    Now I have tested with two different smart implants and 3 different DHT22.
    The first DHT22 did not work, the second and third report the same problem.
    Three out of three faulty sensors seems very strange to me ..
    I connected the smart implant to HC2 first and then to Home Assistant ... in both systems I do not receive data.

    Edited by Roberto R.

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    5 minutes ago, Roberto R. said:

     

    UIn what parameter do I find the offset?
    I don't see it anywhere ..

     

    on each temperatur sensor advanced properties

     

    HCL/HC2

    Please login or register to see this image.

    /monthly_2020_07/image.png.5d280df1e4a976022a1f4d163fccb93d.png" />

     

    HC3

     

    image.png.51886405e3a96b7d8b601dd8d521d1ca.png

     

     

    5 minutes ago, Roberto R. said:

    Now I have tested with two different smart implants and 3 different DHT22.
    The first DHT22 did not work, the second and third report the same problem.
    Three out of three faulty sensors seems very strange to me ..
     

     

    i think if it does not work for you with disabled internal sensor, someone else should check if this is general problem or not

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    Posted (edited)

    I was trying to reproduce the issue with DHT-22 without success...

    Please login or register to see this image.

    /monthly_2020_07/afbeelding.png.bc528ba663d48f6a0969468220fc79e4.png" />

    the inner sensor shows 35 degrees while I heated the Smart Implant case to 52 degrees and DHT-22 is showing correct temperature.

    When I disabled the inner sensor i didn't observe any changes.

    Edited by Bodyart

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