DMS Weather Project: Build Log

Science
#21

@AndrewLeCody did some calcs based on MAX power consumption for the weather module, then factored in for 3 days running. @denzuko has also previously done some calcs based on plans he’d been working on for a while for his own station.

I didn’t do the data collection myself, just echoed some of the data they collected (and wrote it down). That was all done in real time during our meeting: OK for discussion, but needed more formal calcs before execution.

@denzuko plans to do a more formal analysis before we purchase anything.

#22

Need benchmark figures for the board and equipment draw. Building out the unit and plugging into mains with a kill-a-watt meter works well for this.

Most of my designs has been for a single rpi board acting as a mesh node with little usage (runs mystic, cron, babeld, hostapd) and that’s what I’m going off from until we have actual figures from the weather station kit since it’s a different chipset.

So once we have it setup I’ll take those figures and do the maths to get the exact number or panels and lipo cells we need.

#23

By the way the closet figures for sun hours in the dfw area that I found are:

61% of the year with sun, 6.0 hrs summer, 4.8hrs winter, 5.83hrs yearly average.

The 70-80% of that rated value is a little high and I tend to lean towards 55-60% efficiency in my calculations anyways so that 61% of the year with sun is higher than my usual averages. There’s always a way to improve those figures but that’s not something one needs to get hung up on when using solar, the biggest thing is just high end usage and median average over a 60 minute time span.

#24

Of course, standing on the shoulders of giants: https://www.kickstarter.com/projects/sunair/solar-the-missing-low-power-arduino-board-with-gro

#25

If you go solar, going overkill has gotten pretty cheap. An 80W panel and a 20+Ah sealed lead acid battery is likely the cheapest solution, and almost certainly more then enough power for your needs…

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#26

yeah but hard to make portable but that’s a discussion for a different project.

#27

How would you protect it from lightning? what type of cable will you be using?

#28

Looks like the Adafruit board is designed for a 6V solar panel, while the 15W solar panel you list claims to charge 12v batteries (which means >12V output). One 1-star review of the HF panel I read said it was putting out 24V in full sun.

The Adafruit solar panels for which the power board is designed may include buck converters to stabilize the output voltage.

The Adafruit board only supports a single battery - your parts list says 3x batteries and you can’t simply daisychain LiPo batteries together: they need “smart” charging. You could link multiple chargers to the solar panel, but that would add cost.

Will these parts play well together?

#29

If I remember correctly, solar panel voltage can vary a decent bit, as it’s not regulated (that’s up to the charge controller).

#30

Something like this will probably suffice if it is properly grounded.
https://www.amazon.com/Power-Supply-Lightning-Arrester-Protector/dp/B007QR95X8

To account for voltage drop in the long power lead, you might consider running 12v-18v up to the roof then using a 5v switching regulator in the enclosure with the RPi. Most laptop power modules are in this range and I have a dozen or so if you need one.

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#31

Awesome!

So for now we will be just using the Ourweather Plus board instead of powering it through the raspberry pi. But if we choose to go the route of wiring up there these will come in handy.

#32

How would you protect it from lightning?

I would install zener diodes to break down at 150% of nominal DC voltage, possibly adding gas discharge tubes to handle large induced voltages. This will protect from a nearby strike.

Nothing that us mere mortals can afford will survive a direct strike…

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#33

what wiring did you guys use for the HAM antenna. Also are y’all running power up there?

https://dallasmakerspace.org/wiki/Amateur_Radio_SIG:BYOR_Antennas_2016

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#34

Meeting Reminder

When: Thursday, 1/19
Where: Interactive Classroom
Time: 7 p.m. - 9 p.m.

DMS Weather Station Wiki
Calendar Event

Hey guys we’ll be meeting tomorrow night to discuss and complete the following items:

  1. Order Solar Power Battery - @denzuko can you have your calculations completed by the end of the meeting. From there we can make our final decision if we are going solar or not.

  2. Develop a materials list for the station base :white_check_mark:

  3. Design station base :white_check_mark:

  4. Report on outside Cat5e wiring

  5. Set up Database

  6. Test sending temperature information to DMS website

  7. Setup DMSWeather Network

Again all are welcomed to stop by or even help out.

#35

We used LMR400 coax for the antenna, which we purchased, and we used some donated eight conductor cable for the power run.

#36

one last thing where is the eight conductor cable hooked up at? electrical room? HAM bench? Also I know you work on different time schedules than what our meeting is scheduled at, so if you have an idea if we were to use cat5e or (any other wiring ) for powering our station that would be helpful also.

#37

That cable runs from the HAM bench to the box on the roof containing the antenna tuner. The power on it is switched at that bench so that it is only on when the antenna is in use. You would have to ask Zack if there are any available conductors.

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#38

Is the meeting open to non-DMS members? Would I need a laptop to participate? Thank you.

#39

Yes all our meetings are open to non DMS members. I would suggest bringing your laptop for research and fact checking.

#40

Meeting #2 Recap

Last night we went on the roof and tested our station’s wifi connection. Because we were connected to DMS Member we were still unable to connect. We then reconfigured it to DMS Guest thanks to @HankCowdog and @Gimli and were able to have a stable wifi connnection that displayed sensor data. At the time we only had the humidity, temperature and pressure connected to the board. The pressure may be off because we set it at ground level height.

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  1. :negative_squared_cross_mark: Order Solar Power Battery - We did a risk analysis last night and decided it was better to run Cat5e to the roof versus solar power. Although using solar would be neat it may not be efficient for our current and future needs.

  2. :white_check_mark: Develop a materials list for the station base

  3. :white_check_mark: Design station base

  4. :white_check_mark: Report on outside Cat5e wiring

  5. :negative_squared_cross_mark: Set up Database - looking into alternative Weewx able to collect and send data to wunderground.

  6. :negative_squared_cross_mark: Need permission to display temperature data to DMS main website

  7. :white_check_mark: For now the station will use DMS Guest until further notice.

  8. :white_check_mark: Test current - thanks to @gimli, @brianbterry will be doing another test this coming week.

Meeting #3 goals

  1. Build station base - @HankCowdog @David_Steele

  2. Ask HAM radio estimate wire length; ask @Team_Infrastructure recommended lightning surge surpressor; build a materials list for wiring install - @Gimli

  3. Database configuration

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