Author Topic: Outdoor sensor node (Relatively low cost)  (Read 9215 times)

davinci

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Outdoor sensor node (Relatively low cost)
« on: December 07, 2014, 03:39:57 PM »
I have not yet seen any "template" for creating a moteino driven outdoor sensor node that is waterproof, powered by battery and features solar charging. (I know there has been discussions on the need of solar charging on other topics on this forum).

Would be interesting to just start an open discussion about this, and look at "Seeeduino Stalker - Waterproof Solar Kit" (Found here:  http://www.seeedstudio.com/depot/Seeeduino-Stalker-Waterproof-Solar-Kit-p-911.html ) as a good example of this kind of a setup and share links and experiences with alternative materials for this approach.

Personally I've been planning to create some outdoor nodes monitoring temperature, humidity and barometric pressure as a start.

For indoor sensor nodes i find the waterproof casing i linked to, too big and bulky. A smaller white casing with a separate battery room for quick replacement of batteries would be nice. Any tips here would be appreciated.

Already bought some of the waterproof enclosures that I later noticed that the seeduino stalker kit use.

TitleCommentURLCost
Moteino R4Select the one you preferhttps://lowpowerlab.com/shop/index.php?_route_=moteino-r4$20
Waterproof enclosureClear plastic cover for solar panel compatabilityhttp://www.ebay.com/itm/281392320490$2.69
Solar panel55x70mm. Have not found this on ebay at this size. Perhaps someone else is able to find it, or a similar?http://www.seeedstudio.com/depot/05w-solar-panel-55x70-p-632.html$1.95
Li-po battery1000mah 3.7v. One with lower capacity battery could be used to lower the cost for this task?http://www.ebay.com/itm/181601591660$8.90
Solar Lipo Charger (3.7V)No idea if this board is compatible with the other parts. Any experiences?http://www.ebay.com/itm/151331887062$5.50

Cost of material per node would be roughly 40$ with this setup. I find that a fair price. You will ofcourse need to add some sensors that bumps up the materials cost depending on your requirements.

Any thoughts / feedback would be nice.

08.12.14 Update: I bought a couple of each of the components on the list i was missing. (Battery, lipo charger and solar panel)
Will update this post when i get a simple node up and running (probably with a temp sensor).
« Last Edit: December 08, 2014, 07:15:21 AM by davinci »

ColinR

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Re: Outdoor sensor node (Relatively low cost)
« Reply #1 on: December 10, 2014, 03:34:07 PM »
I prefer an American-made, IP-rated enclosure, with mounting flanges: http://www.polycase.com/wc-20f

A 600-650mAh LiPo would make up the difference in price above.

Interested to see how the solar charging works out for you.

C
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davinci

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Re: Outdoor sensor node (Relatively low cost)
« Reply #2 on: December 11, 2014, 08:53:13 AM »
Thanks for the link.

The enclosures from polycase looks better and seems to be of a higher quality than the one I linked to.

Yeah, the battery is probably a bit overkill. I will look into replacing it with a smaller one, perhaps I can downscale the solar panel too.

ColinR

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Re: Outdoor sensor node (Relatively low cost)
« Reply #3 on: December 11, 2014, 03:08:00 PM »
One issue I had with larger batteries is that they are, well, bigger. A 600mAh seems to fit perfectly in my remote node cases, still allowing a screw to reach the PCB boss.

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davinci

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Re: Outdoor sensor node (Relatively low cost)
« Reply #4 on: December 12, 2014, 10:11:41 AM »
What size are the 600mah batteries you use?

I found one on ebay with these dimensions:

Size:
5 mm(H) *30 mm(W)* 40 mm(L)
0.19 inch (H) *1.18 inch(W)* 1.57 inch(L)

ColinR

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kobuki

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Re: Outdoor sensor node (Relatively low cost)
« Reply #6 on: December 14, 2014, 06:41:43 AM »
Be aware that most small sized batteries for RC modeling, quads, etc. don't have the PCM built-in so you can damage them by over-discharge. You can ask the seller though.

davinci

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Re: Outdoor sensor node (Relatively low cost)
« Reply #7 on: December 14, 2014, 03:16:24 PM »
Thanks for the heads up Kobuku! I've been aware of this for the batteries.

There is definitely one big challenge that probably makes the lipo batteries useless for my use.
I should have known that they are not tolerant of charging at temperatures below 0 degrees celcius, and here in Norway (Europe) it's normally below 0 degrees for a few months. It's alot milder climate here in the west, but up north lipo batteries are probably useless.

Do we have any known charger boards for lead acid or nicd batteries,  to get a small-factor charger board and small-sized batteries to charge with a solar panel as we quite easily do with lipos?
Been searching around different sites and reading some blog posts, and it gets complicated..

kobuki

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Re: Outdoor sensor node (Relatively low cost)
« Reply #8 on: December 14, 2014, 04:22:03 PM »
An interesting (sub)project would be to replicate what some companies do, such as in Davis weather stations. Its outdoor sensor suite uses a non-rechargable CR123 lithium battery and a 2.5F supercap. The supercap is charged in daylight using a small solar panel and discharged in the night or when the sunlight is inadequate to charge it and power the electronics. The CR123 is only used as a backup power source when recharging the supercap is not possible and/or there's no sunlight hitting solar panel either. The battery in these stations usually lasts for several years and the supercap is charging below 0 C without problems.

davinci

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Re: Outdoor sensor node (Relatively low cost)
« Reply #9 on: December 14, 2014, 05:41:55 PM »
Very interesting approach. I'm afraid designing such a solution is ahead of my skills within electronics (I'm a C#/Java programmer)

If someone came up with a project/solution on how to do it, I would be keen on trying it out on my future outdoor sensors.

But that would be a big jump towards a nice design for running outdoor sensor nodes with Moteino.

A little inspirational video: https://www.youtube.com/watch?v=xbjpQmjwMyU

kobuki

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Re: Outdoor sensor node (Relatively low cost)
« Reply #10 on: December 14, 2014, 05:55:53 PM »
Well, you can just use primary batteries with the same chemistry as the CR123 (Lithium Manganese Dioxide, usually just Lithium), they're common in the standard sizes. If you can afford space for 3 AA cells, you have like 9 Ah and that should last plenty without a solar cell, even. They're good from -40 C or so, without capacity loss.

davinci

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Re: Outdoor sensor node (Relatively low cost)
« Reply #11 on: December 14, 2014, 06:15:38 PM »
Yeah. I can try 3x aa batteries to start with, and see how long the node will run, it might be just a ok solution to get started and add these solar chargering features later.
Sleeping and not submitting too frequently will help.

TomWS

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Re: Outdoor sensor node (Relatively low cost)
« Reply #12 on: December 15, 2014, 07:50:14 AM »
Well, you can just use primary batteries with the same chemistry as the CR123 (Lithium Manganese Dioxide, usually just Lithium), they're common in the standard sizes. If you can afford space for 3 AA cells, you have like 9 Ah and that should last plenty without a solar cell, even. They're good from -40 C or so, without capacity loss.
One correction, AA batteries are 3300 mAh, 3.3Ah, but 3 of them in series doesn't give you 3X the Ah, it gives you 3X the voltage, including some extra as margin above the 3.3V to operate.   You have more Wattage available, but not longer battery life at given current drain.

Lithium AA cells will supply power reliably at below freezing temperatures, alkaline will not.  (This was probably assumed, but wasn't explicitly mentioned anywhere). 

Good luck with your project!

Tom

kobuki

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Re: Outdoor sensor node (Relatively low cost)
« Reply #13 on: December 15, 2014, 08:21:27 AM »
Reading the datasheet of a well known brand and emploiyng a 10% safety margin on the textbook value, I'd rather say it's 3 Ah than 3.3 Ah. It's debatable though. What is your real life experience with them?

OTOH, I admit that multiplying the Ah capacity by the number of batteries is a little over-simplifying things, but as you pointed out, it provides 3x the energy so the Wh increases approx. 3-fold. It means around 1/3 of the amperage thus 3x longer service time, in general. The end result is the same from this standpoint, and that's what is important.

I explicitly mentioned the usability below freezing temperatures in the post you answered to. Please also see the DS I linked above.

davinci

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Re: Outdoor sensor node (Relatively low cost)
« Reply #14 on: December 15, 2014, 09:14:46 AM »
Am I correct?

One AA battery at 1.3v x 3 in series would provide 3.9~.3.7v as a end result?