ADS1115 vs 0-25v Voltage Sensor on a water tank level setup

Hardware
1

Hello all,

I am working on refining a water tank level sensor that I have made using an ESP-Wroom-32, QDY30A 0-10v and a 0-25v Voltage sensor with ESPHome.

I went down this path for reasons, (initially purchased a Shelly Plus Uni, but it was faulty) so I went with what I already had in my drawer.

I have not seen anyone else post a build of the QDY30A using the 0-25v sensor, instead people seem to use the ADS1115 and I cannot see why.

Would I see more reliability\accuracy if I changed to the ADS1115?

Currently I have fluctuations in readings that seem to match temperature changes. So I am keen to understand if I can rule out the basic voltage sensor I have used and move on to seeing if I need vent holes in the box or need to adjust according to ambient temp.

Thanks for reading and taking the time! I am keen to learn.

EDIT : I fixed my issue, was not relating to the voltage sensor, but needing to ventilate the electronics box so the tank probe can sense the outside air pressure, which seems like a silly mistake now that I know!

Components :
ESP32-Wroom-32 - [https://www.aliexpress.com/item/1005007195400858.html?spm=a2g0o.order_list.order_list_main.113.1c531802D3GE2j ]

QDY30A 0-10v - [https://www.aliexpress.com/item/1005004607235726.html?spm=a2g0o.order_list.order_list_main.118.1c531802D3GE2j]

0-25v Voltage Sensor - [https://www.aliexpress.com/item/1005006962265080.html?spm=a2g0o.productlist.main.1.668d5fb6IxE8km&algo_pvid=81101f10-1fb3-47c2-9f5c-8209421b87db&algo_exp_id=81101f10-1fb3-47c2-9f5c-8209421b87db-0&pdp_ext_f={"order"%3A"67"%2C"eval"%3A"1"}&pdp_npi=4%40dis!NZD!1.68!1.68!!!6.77!6.77!%402103244417373588686128086e2e01!12000038869193383!sea!NZ!713905200!X&curPageLogUid=YgcPVG5hJkjp&utparam-url=scene%3Asearch|query_from%3A]

2

The ads1115 allows analog inputs to be forwarded via I2C to a ESP32 (for example)

The QDY30A on the other hand is a sensor that puts out it readings via an anlog signal.

Your 0-25V “sensor” is nothing but a voltage divider: 25V in will result in 5V out (both analog signal.)

The ESP32 also has native adc input(s).

3

Because people generally don’t buy a module, they use two resistors.

Neither do I.

But first verify what you really have, what’s written on the sensor body (sometimes they send you whatever model they have on hands).

4

The onboard ADC’s are 12-bit while the ADS module is 16-bit. It’s clearly a better solution.

1 Like
5

Not just it has higher resolution, but it’s superior to ESP32 ADC in every sense, especially in case of low voltage readings (esp32 ADC can’t really go below 100mV).

1 Like
6

That totally depends. For example if a sensor only has a 8-bit resolution :person_shrugging:

The mentioned sensor is available in various ranges - including one with a range from 0.1-5V. In any way I would totally avoid analog out-/in-puts and rather choose (any) other available method like rs485 (offered in the linked product) :point_up:

7

Built-in adc in esp32 isn’t exaclty high-quality one, if i’ve read correctly. Supposedly it’s not very linear with noticeably “glitch” at 2.5V and just under max.
It has quite some noise - you can find (overexaggerated) info that it’s in fact 9 bit data and 3 bit of noise :stuck_out_tongue_winking_eye:
Then - depending where you read - some say it can’t go below 100mV, while you can find information about not going even as high as below 0.2V… So, choosing ads1115 is clearly a better.

But, at the end i totally agree with orange-assistant: I’d choose any digital solution. In this case RS485.

8

Thank you, that makes perfect sense.

9

Thank you! I think because I am still learning about these things the resolution specs didn’t sink in for me to understand that. But makes a lot of sense now.

10

While I think Esp32 ADC is … not the best possible, I think it’s capable to detect your 0-10V sensor without problems for your use case. I could immagine that 5% tank level resolution is enough for normal use.

11

So far so good I think, thanks for the reply. At least the readings are close enough to my multi-meter for me to be happy. A long way off where I started!!

I will have a play with the ADS1115 when my new batch of ESP32’s arrive as I have a second water tank to monitor so I am working on getting this first one as close to right before I look at building a second one. That and I will be looking to increase the sensitivity if possible.

I would like to get as much detail as possible, but smooth out the fluctuations as well. So a bit of research on the sensor\maths side in HA to get it better.