Sensebender Micro reports V_HUM > 100

  • Since 2 weeks, my outdoor sensor, a Sensebender Micro with a NRF24L01+, stopped reporting values to Domoticz at night, then resumed during the day.

    Here the temperature goes around 0C with 100% RH.

    After trying to add a capacitor (10uF, then changed to a 100uF), I reflashed the Sensebender, installed the latest gateway on my Raspi gateway, still no luck.

    Then, running the gateway with the debug flag, I noticed that the sensor reported humidity > 100%. And Domoticz doesn't store this value. (Why?)


    So if your sensor doesn't report values to your controller, check that the values are within a valid range.

    For now, I've put some Kapton tape on the Sensebender Micro, so the side in contact with the box is insulated. We'll see how it works.

    I've read all the posts on the forum, there aren't a lot of explanation on how design an outdoor enclosure, so I'll appreciate any hints!

    I'll try nail polish, as seen on this video: How to Waterproof Electronics by GreatScott!

    Hope this post will save you some time diagnosing a non-responding sensor.

  • Mod

    I used an outdoor electrical box for my outdoor sensor (you can look at my solar sensor in the project section) with a tiny hole where the sensor is to allow humidity to reach the sensor. Could it be that your is getting a bit wet?
    Anyway you can constrain the values between 0 and 100 before sending them

  • Hi,

    I saw your post, but i'm using the Sensebender Micro and the Si7021 sensor is on the main board. Hard to just let the sensor exposed to the outside world.

    My Kapton tape insulation didnt work, I'll try to clamp the RH value.

    The Si7021 datasheets explains why this happens:

    Due to normal variations in RH accuracy of the device as described in Table 4, it is possible for the measured value of %RH to be slightly less than 0 when the actual RH level is close to or equal to 0. Similarly, the measured value of %RH may be slightly greater than 100 when the actual RH level is close to or equal to 100. This is expected behavior, and it is acceptable to limit the range of RH results to 0 to 100%RH in the host software by truncating values that are slightly outside of this range.

  • Mod

    Still 100% humidity is quite a lot... I don't get more than 85% when it's foggy.

  • I agree, 100% is a lot, but I had a look to weatherunderground and there's a Netatmo weather station near my house that reports an average of 95% humidity, with a maximum of 100%. So my measure may not be this wrong.

    I'll test with another sensor tonight (or move on, I spent 3 evenings on this)

  • Mod

    Wow, where do you live? Don't tell me about spending hours on silly problems, I lost count for my solar outdoor sensor.

  • @gohan I live in Switzerland, but perhaps my place has more humidity than normal.

    It's not silly problems we're working on, we're learning all the time!

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