How should I calibrate the water/moisture sensor?

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DaveGadgeteer

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May 6, 2015, 5:36:12 PM5/6/15
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The soil moisture sensors (capacitive) start out with wildly various readings.
What is the appropriate way to calibrate them?
Dipping them (how far) in water could mean 100%, but also triggers the water sensor.

DaveGadgeteer

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May 8, 2015, 2:57:05 AM5/8/15
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Is there a way to stop the water/moisture sensor from alarming at Water Detected?
I'm trying to measure dampness in the pot of a potted plant, and often when it gets watered the water detection goes off. I'd like to disable that. I'm only interested in the capacitive moisture sensing for this job.

Tonight one of these moisture sensors started pushing a water detected alarm to my phone every few seconds. It was so annoying. Other people were hearing it even though it was just on vibrate. I finally had to completely power down my phone to stop the interruptions.

Would it help if I broke off the tip of the stick? Scratch off the contacts? They corrode away fairly rapidly, but still cause water detection when I don't want it.

DaveGadgeteer

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May 8, 2015, 8:51:00 PM5/8/15
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Today the system was mercifully quiet, no buzzing my phone constantly.

I finally grew suspicious and looked at the tags. Last night, one tag was mysteriously "out of range", but all others were fine.
Today, every single tag on that tag manager is "out of range"!!!
I guess I'll power-cycle the tag manager. OK, that helped. 9 of 11 tags are now back in range.

I'd still really like to know, how does one set a moisture standard for calibrating the moisture sensors? If you dip them in water, which ought to be 100%, they scream that they detect water. It's not clear that is the same as 100% moisture.

Nicolai Landschultz

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Jun 21, 2015, 12:18:57 PM6/21/15
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Did you ever figure out how to calibrate them?  I've got mad readings many of mine are showing more than 100% the highest at 272% 

I'm trying to use these tags for soil moisture levels for irrigation so it would be nice if I could generate some more meaningful levels

Dave Gustavson

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Jun 21, 2015, 2:22:07 PM6/21/15
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DaveGadgeteer has been banned from membership in this group, so cannot reply to you himself.
However, he tells me he has never received any response to this question except yours, and still does not know how to make the moisture sensor readings meaningful.
There seems to be confusion between sensing water and sensing moisture.
There's no help he can find. The problems persist.
He, like you, wanted to use them as part of an irrigation system, but all they seem to be good for is confirming that the irrigation system did deliver water, which is something but not what he'd hoped for.
He has purchased other capacitive sensors, but integrating them into the irrigation system will take some design work. One can now buy $3 WiFi chips containing a processor and having extra I/O pins, but that approach presumably needs more power than these tags and would require wired connections for power and/or signals. 
It would be nicer if these tags could be calibrated and tamed.

Jeff McCabe

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Jul 5, 2015, 1:24:15 PM7/5/15
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I just started playing with these tags myself, but am assuming that calibration is done by entering a value from another device in the appropriate screen.  For instance, if you know that the temperature in the room is 72 degrees, from another device, and the tag thinks it is 74, one can enter 72 in the calibration section.

I have managed to get the sensors to turn on and off Wemo lights through IFTTT.  I am now trying to figure out how to write Kumo apps to control a Dropcam.  Any help would be appreciated!  I will keep looking.  j

Chris b

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Jul 28, 2015, 4:02:38 PM7/28/15
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did you work this out?

Can you not just insert the device into the pot and set the value  to what you feel is correct then it will adjust as it changes?

glory...@gmail.com

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Jun 30, 2019, 4:02:53 PM6/30/19
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Hi,
It sounds like we are trying to accomplish the same thing with our tags, any luck?

David Gustavson

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Jun 30, 2019, 10:47:25 PM6/30/19
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No luck here, I finally just gave up. Nobody ever provided the recipe/standard to be used.

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David Abigt

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Jul 1, 2019, 1:45:42 PM7/1/19
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Same here I never could get them to give me anything like linear data. I've tried a half dozen each of the v1 and v2s. Love the indoor tags. Even have one each in the freezer and fridge to start screaming if someone does not close the doors well. But the moisture tags seem pretty worthless. Especially as the batteries can not be replaced, the shells seem iffy for outdoors and most did not last me 8 months. But then I've tried several with similar board and blade type probes that did no better.

The most accurate solution I've found for soil moisture I've found so far is the Davis system but that is about $500 for a hub and 4 sensor pairs. And you need to have a weather station console for it to talk to on top of that. And some sort of uplink module if you want to see it on the web like WirelessTags. So getting just getting that first sensor online could easily set you back $1000+.

The most cost effective solution I've found, that works, is Ambient.  It uses a rod probe similar to those you see on the moisture meters. Helps get it down into soil deeper than the board and blade ones too. They seem to track pretty consistently with the Davis sensors. I got mine for $60 and the moisture / temp sensors for $16 each.  Looks like that might have been a sale though as the say $72 and $30 now. Note I recall they were cheaper direct than via Amazon at the time.
Ambient Weather WS-8482 7-Channel Wireless Internet Remote Monitoring Weather Station with Indoor / Outdoor Temperature & Humidity, Compatible with Alexa
Ambient Weather TX-3102 7-Channel Soil Moisture and Thermometer, 16-Point Resolution, for WS-8482, WS-8478A Smart Weather Station
You are limited to 7 sensors but you can use them multiple years since the batteries can be replaced. At least in theory. I've only had mine online 7 months. I've only had to replace the batteries in one so far and I think that one might actually be bad. Even if 1 in 7 is bad still WAY cheaper than Davis. Note there does seem to be a pairing process with the Ambient so maybe you could have multiple hubs but the docs seem to imply you can't. Tempted to try running a second hub though as I have about a dozen plants in pots plus 4 garden sections I'd like to monitor without going broke.



On Sunday, June 30, 2019 at 9:47:25 PM UTC-5, David Gustavson wrote:
No luck here, I finally just gave up. Nobody ever provided the recipe/standard to be used.

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On Sun, Jun 30, 2019, at 4:03 PM, glory...@gmail.com wrote:
On Sunday, June 21, 2015 at 9:18:57 AM UTC-7, Nicolai Landschultz wrote:
> Did you ever figure out how to calibrate them?  I've got mad readings many of mine are showing more than 100% the highest at 272% 
> 
> 
> I'm trying to use these tags for soil moisture levels for irrigation so it would be nice if I could generate some more meaningful levels
> 
> On Saturday, 9 May 2015 01:51:00 UTC+1, DaveGadgeteer  wrote:
> Today the system was mercifully quiet, no buzzing my phone constantly.
> 
> 
> I finally grew suspicious and looked at the tags. Last night, one tag was mysteriously "out of range", but all others were fine.
> Today, every single tag on that tag manager is "out of range"!!!
> I guess I'll power-cycle the tag manager. OK, that helped. 9 of 11 tags are now back in range.
> 
> 
> I'd still really like to know, how does one set a moisture standard for calibrating the moisture sensors? If you dip them in water, which ought to be 100%, they scream that they detect water. It's not clear that is the same as 100% moisture.

Hi,
  It sounds like we are trying to accomplish the same thing with our tags, any luck?

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Zhiheng Cao

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Jul 2, 2019, 4:32:42 PM7/2/19
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To calibrate a water sensor dip the entire sensing surface into water, click update (at this point it may read above 100%) then go to the settings screen, enter 100% into calibration box click Calibrate. Next wipe the sensor clean and dry, click update. You should see a much lower reading. Open settings screen again and enter 0% and click Calibrate.

A failure mode of water sensor when used under direct sunlight for too long, is that it reads 2000% regardless of wetness level. This is caused by electrical short of the capacitive sensing surface because the coating fakes allowing rust to form inside. The next batch of water sensor will have improved coating pattern to increase the life expectancy of such case.

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Jamie Murdock

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Jul 2, 2019, 5:23:08 PM7/2/19
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Zhiheng, I appreciate your transparency with a coating fakes issue you had. If the 10 moisture sensors I purchased (5 in April and 5 in May 2019) for use in soil moisture monitoring are impacted by this issue, is there a DIY overcoat, epoxy dip, etc that I could apply on my units that would keep them running until the battery wears out?

Your calibration instruction would be a handy thing to add to your support pages. 

Thanks
Jamie Murdock

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David Abigt

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Jul 3, 2019, 1:31:47 PM7/3/19
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I only had one that did the 2000% thing. Rest would just vary wildly. I thought it might be temperature related since temp always seemed off as well but did not have the time to compile that level of data. That would seem to track though as the ones that work for me read the temp in the probe instead of the head.
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Andrew Kessel

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Jul 3, 2019, 4:39:05 PM7/3/19
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I just tried  Zhiheng's method on one moisture tag, and when placed the tip in water, it reads infinity/2000%.
I noticed there was some corosion on one of the tips (same metal both sides - the kind of copper tips), and used a soft abrasive to clean it.
That seemed to fix the problem, though obviously its going to have issues again.

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