Water level indicator, the pressure dropped again after measuring

ESPHome
1

Hi,

I would like to correctly record the water level of my motorhome using pressure measurement.

I have connected the pressure sensor (MPS20N0040D) incl. analog/digital wander ( HX710B) (MPS20N0040D-S HX710B 24-bit ADC 0-40KPa Drucksensor Wasser Level Modul) to an ESP32-C3 mini. Everything is supplied with 5V.

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The ESPHome-Yaml looks like this:

sensor:

  • platform: hx711
    name: “HX711 Value”
    dout_pin: D0
    clk_pin: D1
    gain: 128
    update_interval: 2s

If I change the pressure in which the water level rises or falls, I also get measured values for the rise / fall of the pressure BUT this value is not retained. After the rise, for example, the pressure falls back to the basic level.

What am I doing wrong? The pressure should actually remain the same as long as the water level does not change.

Thank you and best regards

Attila

2

Hello,
well it is possible you have a leak?
Just try connecting a plastic syringe on the plastic pipe and apply pressure.

have you tried:

sensor:
  - platform: hx711
    name: "Raw Value"
    id: raw_value
    dout_pin: GPIO2
    clk_pin: GPIO15
    gain: 128
    update_interval: 60s
    on_value: 
      - sensor.template.publish:
          id: water_level
          state: !lambda "return 100.0*((x-id(zero_value))/(id(full_value)-id(zero_value)));"
  - platform: template
    name: "Water Level"
    id: water_level
    unit_of_measurement: percent

not my code comes from this post:
https://community.home-assistant.io/t/simple-and-cheap-water-level-sensor/765310?u=autodiy

3

These are good ideas. I’m going to try the following at the weekend:

  1. see if this pressure sensor is tight.
  2. query the sensor not so often (1s) but go to 60s.
  3. try out the Yaml file mentioned above.

I will report back.

4

Somewhat old thread, but did you ever solve this? I am having the same issue where the sensor detects change but the values decay over time

5

Sounds like leak…

6

Sorry for the late reply.
I rejected the implementation using a pressure sensor. Far too vulnerable as a sensor in the RV tank.

In my opinion, the problems described above have the following causes, which would be too difficult to resolve:

  1. The sensor is very sensitive in terms of tightness and robustness. Slight changes during testing / modification also change the sensor so that repeatable results are not achieved.

  2. The hose has to be really tight. The hose must be thick. If he gives in, it distorts the values.

  3. No water may spill up to the sensor.

  4. The external pressure must be included in the formula otherwise the values ​​are not constant and the weather has an influence on the data.

I have now switched to a ToF sensor for my water tank in the motorhome. It uses a laser to measure the distance from the supply opening to the water surface. I build the whole thing in a 3D reprint of the supply cover including battery operation.

7

Did you find a waterproof ToF sensor? Which one did you end up buying

8

Just as waterproof as the air pressure sensor. I placed/protected it directly behind a thin plexiglass pane, which worked without any problems. She just has to be thin. I think 0.4mm.

Because I’m currently using it, there’s another one that can measure further.

Importantly, he doesn’t like direct sunlight. But that’s not a problem in a tank.