Searching on Aliexpress I see that they have a sensor (QDY30A) that comes in different versions.
Providing either 4-20mA, 0-5V, 0-10V or even RS485 output.
The 0-5V version combined with a ADS1115 seems to be a very simple solution.
Does anyone have any experience with this sensor?
I don’t have any experience with this sensor, but the reason there are 4-20mA sensors is that the longer a cable is the lower the voltage will be so if you’re measuring amps, the cable length doesn’t affect the measurement, and you can detect a broken cable if you’re measuring 0 mA
@Syntox Yes, but all the examples here only convert the current to a voltage in order to read it off an analog GPIO on the ESP anyway. So the only advantage then is that you would not have to (re)calibrate for voltage drop in a longer cable.
Is there a convenient way to read the current directly on the ESP? I see there are chips like INA219 - is that an alternative to using the ADS1115?
I guess this Post will help you:
@Syntox Not really.
I’m looking at using the INA219 to read the current directly on the ESP. I cannot see that this is disussed in the thread. My concern is that this has a precision of 0.8mA and that might give a too coarse resolution to be practical with the pressure sensor.
For those that might be interested.
I just tested a setup using a ESP32 with a INA219 current sensor module, measuring the the current of a TL-136 water level sensor (0-1 meter version, 4-20mA).
I tested it in the range from 0 to 20cm and it seems to give stable measurements from 4-7.3mA with a precision of ~0.1mA. This fit the INA219 specification with internal gain set to 400mA (div8).
This means that one should be able to monitor water level from 0 to 1 meter with a precision better than 1cm.
I’ll continue testing this and will report my findings.
Just for the sake of comparison:
I got a 0-2m pressure sensor which reports in 4-20mA and am using a current to voltage converter and my accuracy is about 1mm. So I have higher accuracy but also a more complex set-up perhaps. More info about that can be found in posts above 
Yes, your set-up might give higher precision, but is also more complex.
The INA219 connects easily to the ESP32 using I2C and is directly supported by ESPHome, so the setup is extremly simple.
With 0.1mA precision it will give you appx. 160 measuring points on a 4-20mA sensor. This is enough for a precision of less than 1cm for a 0-1 meter sensor, and a bit more than 3cm for a 0-5 meter sensor. For my purpose this is more than good enough.
Hi all,
Lots of interesting ideas above!
I’ve finished my water tank level sensor and successfully read level in range, volume/litres, and %. My project is Wemos D1_mini based, and my level sensor is the JSN-SR20 (ultrasonic, waterproof, dual-sensor model of HC-SR04, around AU$8). This sensor has a dead band of ~5cm so can be readily mounted direct to the top of the tank - no cone or spacer required, simplifying installation. It also has a range over 4m, for those with tall tanks! I’ve added a DS18B20 for external air temp, to round things out, and a rainfall sensor to tell me when it’s raining.
To get reliability I’ve added the following parameters (not mentioned anywhere above, but in the sensor docs) for the ultrasonic sensor:
Pulse_time extended to 20us. The default is 10us, whereas most sensors want a minumum of 20us.Timeout set to 3m. The default is documented as 2m, but my sensor wouldn’t reliably report values over 1.80m without this.I was getting regular “timeout” and “nan” values in my returns prior to adding these; none in the days since.
Others have noted time-of-day variability which would be temperature sensitivity - which I’m also seeing (tank level is currently 3cm overnight but 7cm when air temp is around 18C). There are arduino libraries to reduce temperature sensitivity, but not sure how to implement something like this in ESPHome. Has anyone had success in reducing temperature sensitivity?
This is a great discussion. I’m contemplating adding a water level sensor in my above ground pool, so that it can stop the pump from running ‘dry’ if the water level is too low.
I’m thinking about placing it in the skimmer, so that it won’t be affected by the kids playing in the pool.
The skimmer is only about 20 cm’s high, so not much room to play with, but I’m thinking about using the TL-136 (0-1m) with INA219. If the water level is too low, the pump will empty the skimmer and suck in water, so there should be enough ‘room’ for a proper measurement, just a bit unsure of how the current of the water flowing through will affect the sensor?
I’ve finished my water tank level sensor yesterday, and I’m very pleased with the result !!!
Hadware :
TOTAL : about 40-45€ including shipping costs
The water pressure has a sensor for outdoor pressure that will help to take into account outdoor pressure when measuring water tank pressure.
The water pressure sensor output goes from 4ma et 20ma. The current converter allow a way better precision than using directly a pressure sensor that gives a voltage.
The current convertr can be adjusted. I’ve set mine to give 0V when water tank if empty, and 9V when it is full.
Accuracy is amazing !!! The Shelly displays voltage with 2 decimals and that’s very very stable. It means I have about 900 possible measures on a 3000 Liters water tank. That’s a 3.3 liter accuracy !!
Unfortunately, Home Assistant native Shelly integration only reports a 1 decimal rounded value, so that’s only 90 possible measures and a 33 liter accuracy which is enough for my usage indeed.
And this value is not reported at all through MQTT so there is no workaround this way either.
and you place the sensor on the ground of your tank?
Yes.
It’s heavy, so it goes down by itself.
sounds interessting. actually i do it with an ultrasonic sensor but it is not really reliable
That sounds like it should be OK. Flow around the sensor could be an issue but it’s a fluid so it won’t affect the pressure much - if it does you could place a small baffle (say a vented 3cm PVC pipe around it).
If you’re only concerned about a single level, wouldn’t a simple $2 tilt sensor (like Horizontal Liquid Float Sensor Switch Side Liquid Water Level Sensor Controller Automatic Water Pump Controller For Tank Pool|Flow Sensors| - AliExpress) do the job? No need for current/voltage conversion etc; I have one of these in my rainwater tank, been there 10+ years and still works to prevent pump run-dry,
Yes, that was my original plan, and I already have a couple of them here. The problem is that there is not enough room.
A general skimmer looks like this:
But I can’t find that on aliexpress / banggood?
I’m going to do some more measurement, maybe I can get the horizontal switch in a smaller version than the one you linked (which is the exact one I have) or maybe even try to fit something like this:
?
Yes - limit space will restrict options. I’ve added a rain sensor to my install, but after one rainy day I’ve got “wet” conditions several days later. I suspect water in the connector where it won’t quickly dry out, so may have to seal that area to get reliability.
You could have the same problem with the Grove level sensor above given the humid environment, but as you’re only looking for wet/dry output maybe go low-tech: use a “rain-drop sensor” like…
Similar to the Grove unit but has electronics separated, so you can do away with the actual level sensor and just bare the ends of the cable (ends spaced a centimetre and positioned at the required low-water height) with cable connected to the same level sensor sub-board?
Ok, I went with two of the very cheap
I managed to find some spots where they could be mounted, and just misss the weir, and the basket could still be removed…
They are created with device_class: problem, so they say ‘ok’ or ‘problem’, which suits the task at hand.
The lowest one is open for ok, and the highest one os open for problem.
Looks good, the failsafe redundancy is a nice idea. Hope they do the job!
I have a thrown in level sensor from dfrobot connected through a current to voltage converter and a node MCU. I get the random voltage spikes and voltage variations throughout when no water is being added or removed see below. Can someone please help? Could this be related to the tank heating up and the water inside as the sun hits the western side of the house in the afternoon. Because it is always in the afternoon around the same time. Is anyone else seeing this?
My ESP config is:
sensor:
