Plant watering alarm/reminder gadget

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Bat 'n' Ball
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Plant watering alarm/reminder gadget

Post by Bat 'n' Ball »

Hello,

I'm currently experimenting with an electronic 'watering reminder' gadget which I bought from Amazon. The device I refer to is here (manufacturers website):
https://www.az-delivery.de/en/products/ ... eitssensor

It's very well made with a thick ridged PCB and surface-mount components. There's no pretentious or flashy branding. It is what it is - raw, naked electronics on a printed circuit board!

The setup is fairly straight forward. You wait until your cactus/succulent/whatever-plant needs to be watered. You then put the hygrometer device into the soil (permanently), and press the button to teach it 'this is dry'. You then water your plant.

The device subsequently 'chirps' occasionally when it reaches the dry point which you taught it. There's an ambient light sensor on the device which silences the chirps when it's dark, so it won't wake you up (but the little LED will intermittently flash).

Their literature states:
'This capacitive humidity sensor uses capacitive humidity measurement and makes no electrical contact with the soil, avoiding electrode corrosion and soil electrolysis, resulting in better accuracy and longer battery life.'

I'm currently trailing this electronic device in my Opuntia subulata pot. It's getting to the point where I would normally water it but I've heard no chirps yet which is slightly worrying!! I'll report back when I have a positive result...

For elderly relatives or anyone who might be a bit forgetful (me!) this might be something worth considering. As above, I'll report back with my findings when I have a better idea as to the accuracy of the device 🙂
-- Paul.
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jerrytheplater
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Re: Plant watering alarm/reminder gadget

Post by jerrytheplater »

Paul. Have you thought of weighing your pot to track the weight loss as the pot dries? This will not include weight gain from the growth of your plant.
Jerry Smith
Bloomingdale, NJ
45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
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Bat 'n' Ball
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Re: Plant watering alarm/reminder gadget

Post by Bat 'n' Ball »

jerrytheplater wrote: Fri Sep 02, 2022 5:49 pm Paul. Have you thought of weighing your pot to track the weight loss as the pot dries? This will not include weight gain from the growth of your plant.
Hi Jerry,

I hadn't thought of that and it sounds like a great idea. The simplest ideas are often the best. I would still have to remember to get the digital scales out, though! Luckily, cactus generally survive long periods of drought, when forgotten about.

As far as the small 'capacitive hygrometer' goes which I'm testing, it seems to be very good and not just a gimmick.

It's not small, though, at 14cm long - 7cm sticks into the soil and the other 7cm (with the surface mount components on) is above the soil. So, it would be less conspicuous in a larger pot.

61AqjhitrnL._SL1500_.jpg
61AqjhitrnL._SL1500_.jpg (40 KiB) Viewed 1222 times

You can hear the sound it makes here! The first two chirps give you an idea of the frequency to which it alerts you, and the third chirp is when it is being watered. It goes silent after that until it reaches the dry point again:
https://drive.google.com/drive/folders/ ... p=sharing

I have a cactus which I've had for over 5 years and I'm going to give it to someone I know who has never kept cacti before. I could just tell them to give it a good ol' drenching when it's bone dry (which is basically how I've looked after it!) but this gadget should also remind them that it's bone dry.

I will definitely experiment with the pot-weighing method. Thanks for your advice 🙂
-- Paul.
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jerrytheplater
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Re: Plant watering alarm/reminder gadget

Post by jerrytheplater »

Bat 'n' Ball wrote: Fri Sep 09, 2022 1:18 pm
jerrytheplater wrote: Fri Sep 02, 2022 5:49 pm Paul. Have you thought of weighing your pot to track the weight loss as the pot dries? This will not include weight gain from the growth of your plant.
Hi Jerry,

I hadn't thought of that and it sounds like a great idea. The simplest ideas are often the best. I would still have to remember to get the digital scales out, though! Luckily, cactus generally survive long periods of drought, when forgotten about.

As far as the small 'capacitive hygrometer' goes which I'm testing, it seems to be very good and not just a gimmick.

It's not small, though, at 14cm long - 7cm sticks into the soil and the other 7cm (with the surface mount components on) is above the soil. So, it would be less conspicuous in a larger pot.


61AqjhitrnL._SL1500_.jpg


You can hear the sound it makes here! The first two chirps give you an idea of the frequency to which it alerts you, and the third chirp is when it is being watered. It goes silent after that until it reaches the dry point again:
https://drive.google.com/drive/folders/ ... p=sharing

I have a cactus which I've had for over 5 years and I'm going to give it to someone I know who has never kept cacti before. I could just tell them to give it a good ol' drenching when it's bone dry (which is basically how I've looked after it!) but this gadget should also remind them that it's bone dry.

I will definitely experiment with the pot-weighing method. Thanks for your advice 🙂
You are welcome.

Is there a danger of water getting into the electronics? Would heat shrink tubing help?
Jerry Smith
Bloomingdale, NJ
45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
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Bat 'n' Ball
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Re: Plant watering alarm/reminder gadget

Post by Bat 'n' Ball »

Personally, I think the device is fine as it is.

Heat-shrinkable tubing could potentially have the opposite of the intended purpose and hold splashed water over the components for a prolonged period of time. Heat-shrinkable tubing would have to be very well applied and completely airtight, with the top and bottom sealed perfectly.

I don't think it's needed, though. Even if you blatantly poured water over the electronics (which you wouldn't), the device is extremely low current and should be fine until it dried to the open air.
-- Paul.
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jerrytheplater
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Re: Plant watering alarm/reminder gadget

Post by jerrytheplater »

OK. You know what it looks like better than I.
Jerry Smith
Bloomingdale, NJ
45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
DaveW
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Re: Plant watering alarm/reminder gadget

Post by DaveW »

The problem with most watering devices I have come across is they don't work too well with small pots since the soil is not deep enough. Also, with gritty dry type cactus and succulent soils not in intimate contact with the length of the probe.

With sensors permanently in a pot you would need one for every pot, or at least one in all similar pot size as different sized pots dry at different rates. However, I have only used the ones that depend on galvanic action. Also keep jabbing the sensor into a pot could damage the roots.

Anyway, will be interested to hear your results as I have not seen that type before? Have you tried it with a transparent container filled with your normal potting soil to visibly see through the sides if the soil is dry when the sensor says it is? Say using the bottom cut off a clear plastic water bottle or similar as a pot with a drainage hole drilled through the base?
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Re: Plant watering alarm/reminder gadget

Post by jerrytheplater »

DaveW wrote: Tue Sep 20, 2022 9:25 am The problem with most watering devices I have come across is they don't work too well with small pots since the soil is not deep enough. Also, with gritty dry type cactus and succulent soils not in intimate contact with the length of the probe.

With sensors permanently in a pot you would need one for every pot, or at least one in all similar pot size as different sized pots dry at different rates. However, I have only used the ones that depend on galvanic action. Also keep jabbing the sensor into a pot could damage the roots.

Anyway, will be interested to hear your results as I have not seen that type before? Have you tried it with a transparent container filled with your normal potting soil to visibly see through the sides if the soil is dry when the sensor says it is? Say using the bottom cut off a clear plastic water bottle or similar as a pot with a drainage hole drilled through the base?
I like this idea!!!
Jerry Smith
Bloomingdale, NJ
45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
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Bat 'n' Ball
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Re: Plant watering alarm/reminder gadget

Post by Bat 'n' Ball »

DaveW wrote: Tue Sep 20, 2022 9:25 am The problem with most watering devices I have come across is they don't work too well with small pots since the soil is not deep enough. Also, with gritty dry type cactus and succulent soils not in intimate contact with the length of the probe.

With sensors permanently in a pot you would need one for every pot, or at least one in all similar pot size as different sized pots dry at different rates. However, I have only used the ones that depend on galvanic action. Also keep jabbing the sensor into a pot could damage the roots.

Anyway, will be interested to hear your results as I have not seen that type before? Have you tried it with a transparent container filled with your normal potting soil to visibly see through the sides if the soil is dry when the sensor says it is? Say using the bottom cut off a clear plastic water bottle or similar as a pot with a drainage hole drilled through the base?
Hi Dave,

I’ve been testing this device now for maybe 3 months or so and was so impressed, I bought the company! Just joking - you have to be of a certain age to appreciate that one!

Seriously, I found it accurate enough to warrant me buying another five. At the time of writing, in the UK they are £4.79 for one, £11.29 for three (£3.80 each), or £13.99 for five (£2.80 each).

The battery, a CR2032, is a very tight fit. It’s not included, so these need to be purchased separately. Polarity is negative to the circuit board and positive to the metal holder. I haven’t tried it, but I would imagine a thinner CR2025 would work just as well because of the spring-loaded battery holder. But, a thinner battery would probably not last as long. In fact, I have some other types. Let me just check…

… Yes, I can confirm the thinner CR2025 and the very thin CR2016 also fit just fine. But, as above these would presumably not last as long as the thicker CR2032. I have no idea as to the battery life, but for future reference I will report back when one of my devices fails due to battery depletion.

They are designed to be permanently inserted in the soil, living alongside your plant and alerting you to your plant being dry, rather than you having to periodically remember to insert a pronged resistive-device into the soil to check how dry it is.

I see no reason why it would not work just as well in a small pot vs a large pot. Basically, when you know your plant needs to be watered, you press the small button to teach it the dry point. This only needs to be done once, unless you want to re-program it to a different dry point. The electrodes measure water content via capacitance as opposed to resistance and make no electrical contact with the soil. As long as it knows what ‘dry’ is, it should alert you to that threshold, whether it’s a small pot or a large pot.

Its total length is 14cm. The visible length will be less than that depending on how deep you insert the device, but normally you would only see 7cm of that length. It will be less conspicuous in a larger pot, but if being alerted to your plant being dry is more important to you than aesthetics, then this gadget should suffice.

When my devices chirp (soil is dry), I have stuck my finger a few centimeters into the soil to confirm the accuracy. To me, they do seem accurate and I have no reason to think otherwise. I don’t think it’s really necessary use a transparent container ‘to visibly see through the sides if the soil is dry when the sensor says it is’.

However, in the spirit of experimentation I have done just that! Furthermore, I have sown some seeds in said container… I now have a clear water bottle chopped in half with five holes in the bottom, filled with ‘cactus compost’, identification-unknown cactus seeds sown on the top and a capacitive hygrometer sitting in the soil... what could possibly go wrong?

If anyone does try one of these gadgets, one tip I would mention is to avoid moving or nocking the device once you have set it. If you subsequently knock the device, you might displace the position of the electrodes and alter the capacitance, therefore change when it alerts you.
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-- Paul.
DaveW
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Re: Plant watering alarm/reminder gadget

Post by DaveW »

I am old enough to remember before he bought the company! LOL Look forward to seeing your results. I suppose you could use a sensor in each sized pot, but pots in different parts of a greenhouse could dry at different rates. As I have at a guestimate around 900-1000 plants one in each pot would be expensive.
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Bat 'n' Ball
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Re: Plant watering alarm/reminder gadget

Post by Bat 'n' Ball »

Yes, 1,000 devices would be an expensive way to drive yourself mad with all that chirping. But, for the odd plant or two which might need a bit of extra care, they are worth considering.

For the real geeks out there, you can also program the device via the In-System Programming (ISP) header on the board and connect it to a Raspberry Pi or PC - In theory, your plant could send you an email when it needs a drink!
-- Paul.
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nachtkrabb
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Re: Plant watering alarm/reminder gadget

Post by nachtkrabb »

Hi Bat'n'Ball,
real interesting "toy". I especially love the mail from my cactus.
Before you move to weighing your pots on a regular basis, ask your plants how much jogging or hiking they like. :lol:
N.
Love and Revolution!
...and still more cacti.
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Re: Plant watering alarm/reminder gadget

Post by ohugal »

Bat 'n' Ball wrote: Thu Sep 22, 2022 6:01 am In theory, your plant could send you an email when it needs a drink!
Or other members of the forum... :)
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