Apogee Sensor from a Solar Panel and Battery

Here is what seven days of readings look like in a backyard.

The sensor consumes 52mA or 0.26 Watts continuously which amounts to 6.2 Watt hours a day. Most power banks shut off at this current level, but the Voltaic batteries have an Always On function which keeps the output activated no matter the power draw.

The Setup

To power the system, we paired the 6 Watt panel with our V44 USB battery. In unshaded conditions, the panel should provide sufficient power throughout the year. The battery will run the logger for 6-7 days without any sun. Having the buffer allows the system to continue running during multiple days of heavy cloud cover.

We placed the battery in a waterproof Nanuk case.

Case, sensor and solar panel were all mounted on a pole. The panel attached via our universal bracket and the sensor via Apogee’s Solar Sensor Leveling Plate.

The plate has a handy level that allows you to know when it is pointing straight up.

Data Logging Results

The system powered by the 9 Watt panel and V44 ran for thirty days without interruption and did not appear to go much below 3/4 battery capacity. The limiting factor in the end was the 10,000 readings. We logged every 60 seconds which results in about seven days of readings. To store data over longer periods of time, be sure to reduce the logging rate to account for your desired time range.

Apogee Sensor from Battery Only

Across the US, Schuyler Smith conducted a similar experiment. He connected a SQ-520 sensor to the V44 battery on its own and placed the system in both the front yard and the backyard. Based on the results, he determined that the backyard was a better location for his garden bed. You can read the full post here on Apogee’s site.

The bottom line is that it is relatively straightforward to power the Apogee sensor off grid.

The dashboard is available on Adafruit I/O on any device with a browser.

The sensor is located near the site of two combined sewer overflows (CSOs) that may discharge human waste into the water during a heavy rain event. They are each about 100 yards away from the sensor.

Tutorials for construction of the sensors including a parts list, wiring diagram and source code are here (part 1) and here (part 2).

To make the system water ready, we placed added three waterproof glands on the base of a Nanuk 904 case. These ranged in size from PG7 (plastic) to PG5 (brass) and were selected based on the diameter of the sensor cable.

For double protection, we sealed the inside of the case with epoxy.

When launching, we had several concerns.

Power Management

Even with the panel oriented horizontal to the water and shading from trees and steel structures, the system is ably powered. The 9 Watt panel plus V44 44 Watt hour battery has so far kept up with the power demands of the system of 2.2 Watt hours per day through a fairly cloudy early October. We will observe how the system performs through the winter, but it appears we are probably well over-sized on both battery and panel.

System Accuracy

Temperature performance matches what we are seeing in local waterways. The basin is shallower and the sensors are close to the surface so we are seeing one degree fluctuations on a daily basis.

The dissolved oxygen has been fluctuating on a diurnal cycle between a maximum of 5.71 to 2.96 mg/L for the first 23 days. Over the last six days, the readings have fluctuated between 9.4 and 0 mg/L with no clear diurnal cycle. We suspect this is a biofouling issue.

Cellular Signal

The Brooklyn Navy Yard is an industrial area with lots of steel structures that seem to make cellular signals go haywire. The signal in the basin floats between 1 and 2 bars on Verizon. We are seeing the system send signal inconsistently. When the system cannot complete a signal, it goes to sleep for two hours and then tries again.

In a redesign, we would put a cellular antenna on the outside of the case.

Please reach out to us about your remote monitoring project.

A dark tower of volcanic rock shrouded in clouds dominates the unearthly landscape. Formed millennia ago when high pressure magma solidified inside the vent of an active volcano, it’s presence is foreboding. This is the peak of Cão Grande, a 370m volcanic plug situated deep in the jungle on the island of São Tomé in sub-saharan Africa.

Prior to the expedition, I’d spent a year planning (mainly dreaming) of the day I would be able to visit this island whose landscapes resembled a scene from a Jurassic Park movie. It was a project I knew was ambitious on so many levels. Everything had to be carefully planned and arranged as the island offers almost nothing in the way of purchasable goods or medical help. If something was to go wrong, we would be on our own.

Arriving on the island was a cultural eye opener. Stray dogs running wild through the busy streets, a seven person family riding a single 125cc motorbike, a balancing act fit for a circus performance. Navigating the narrow roads that winded south from the capital we arrived at Agripalm plantation, the furthest point we could reach before being forced to continue on foot through the jungle.

A 3km hike through thick jungle and we emerged at the base of the wall, greeted unknowingly by a 100m high roof that jutted out some 30m. There was no information on the peaks rock formation prior to arrival and standing at the base we gained a very real sense of the task at hand.

Three weeks of 14 hour days later and we were stood on top of the peak. Reaching the summit had been wrought with difficulties that threatened to end the project from the start, many of them not climbing related. Luggage problems, blown battery chargers, generator issues, snake bites, jungle logistics, currency exchange, sickness and stuck vehicles all looked that they would stop us in achieving our goal. However, with each new obstacle that stood in our path, we would find a solution, though non were what you would describe as “traditional”.

Having now completed the route and with time to reflect upon the island, the peak and the people we have encountered along the way. I am thankful in all that I have gained from the trip which amounts to a lot more than just a new route, but new friends, skills and an understanding of a life where people are masters of their environment.

About Gareth Leah:
In addition to climbing, Gaz is an author, Director of Escalando Fronteras and Founder of Adventure 4 Good.

About Matthew Parent:
Matthew Parent is a Los Angeles photographer and camera operator. Follow him on Instagram.

About the Gear:
Gaz and Matthew used the Arc 20W Kit with the V72 battery (now available as the upgraded V88 Battery Pack) encased in our solar-ready Nanuk box. The Nanuk provided a waterproof seal for the battery in an environment that was rainy and consistently wet. “The V72 and large panel were also really tough. I’ve dropped them, stood on them, rocks have landed on them and some how they still work!”

Due to the nature of the types of productions we film, one of Ultralite’s biggest challenges is reliable power on location. We’re usually not simply trying to power one device, but multiple camera batteries, MacBooks, phones, GoPros, etc. On a recent shoot to Cayo Costa we had great success using two Arc 20W Solar Kits at our camp. These were enough to power a couple V72 laptop batteries (now available as the upgraded V88 Battery) daily. The batteries provided plenty of power for our various daily charges plus powered a USB Touchlight hanging over our workstation at night.

Arc 20W kit charging up at camp

Our primary shooting location was actually from ocean kayaks around the island but because we were able to return to camp each night, we could leave the panels lashed to our tents during the day to power the batteries. Each night after we wrapped, we could then go back and get everything charged as we slept. While the island does offer a few 110 outlets at the ranger station, it was located about a mile’s walk from our camp and was generally an inconvenience to access when we returned from production each evening.

Charging phones while taking a break from shooting

If we would have needed to charge directly while on the water, we would have used our 17 Watt Solar charging kit with a Nanuk 904 case, as it is a fully waterproof systems. While the Arc 20W kits are not, they are foldable and a bit more compact, and I personally prefer them for backpacking and carrying on planes. (You can learn how we previously used the 17 Watt Kits in Panama and the San Blas Islands here.)

Photo and words by Bud Force, Ultralite Films

Background: Ultralite Films‘ director Bud Force recently spent some time on the island of Cayo Costa off the West coast of Florida with Jose Azel, president of Aurora Photos, to capture still photography and video for Jackson Kayak, Backpacker Magazine, and Aurora Photos.

The island is still in a very natural state and looks much as it did when first discovered by Spanish explorers. Cay Costa is now a Florida state park and features a plethora of wildlife ranging from wild hogs to alligators to manatees.

You can read Bud’s complete field journal of the shoot at www.ultralitefilms.com/blog.

To share his adventures with friends, family, and sponsors – Kedyn took along one of our famously tough 17 Watt Kits with a custom Nanuk waterproof case. Even with the temperate rain forests and cloudy days, Kedyn was able to keep his Nikon D810 and D7100 powered up and ready to capture the beauty of the Northern Lights and more.

We’re happy to be a part of Kedyn’s journey and wish this inspiring young photographer the best in his next adventure. To read more about Kedyn’s adventure and to see more photos visit his blog here.

I have a love affair with the San Juans Mountains. This stretch of the Rockies are steep, deadly and seem more beautiful every time I visit them. The icy lakes, cold rivers, and variable extreme weather make for interesting adventures and photos. After completing my latest short time lapse film StateScapes: Nevada I decided to shoot my next project about Colorado which means lots of time in this rugged area.

For StateScapes: Colorado I wanted to push the boundary a bit and do something more advanced than your typical time lapse film and by that I mean long term work. I have a few set ups operating now and each is a little bit different as I work on building the perfect kit. My first kit is a Canon 20d which is powered from a full size car battery. If you’ve ever lifted a car battery then you know how heavy those batteries weigh then you know it’s not very practical to haul to remote locations.

My second kit is a light weight solar powered GoPro which I placed in the San Juans near an abandoned mine to show the deep snow piling up over the mine. The GoPro is programmed to take photos every 30 minutes throughout the day in order to capture enough photos to make a sequence where the light is similar day to day. In post production, I will remove abnormally dark and bright frames in order to make the shot smooth and clean.

The GoPro is rigged up to a V44 battery in always on mode and a 9 watt solar panel for power.  The GoPro turns it self on and off every 30 minutes to save battery and with the V44 topping off the camera this set up could, in theory, shoot until the camera malfunctions or the card fills up even in the rainy, cloudy San Juans.

This Voltaic set up is lightweight and portable something my other set up is not. I set the camera up on a hill and then built a fortress of rocks around the camera. The solar panel is positioned to get the maximum amount of sun everyday to keep the V44 full enough to top off the internal GoPro battery.

When creating time lapse films I’m always looking for ways to help tell a story and with so much mining history in Silverton and the entire state of Colorado, this shot will help add historical context to my short film. See you all in a few months when the shot is complete!

This tutorial details how to replicate the your own solar powered sensing project. For a brief overview about the project and the dust sensor testing results in Brooklyn NY, see the overview post here.

If you want a one-on-one conversation with someone from Voltaic about running small systems offgrid, you can schedule a consultation here:

Schedule an IoT Consultation

Project Overview

This project seeks to send real-time air quality information to the web as easily as possible. Anyone with basic experience with sensors or electronics can assemble the hardware below and download the software for the Arduino to get their sensor up and running in no time. An inexpensive dust particle sensor was combined with an Arduino Uno to record pollution levels, and a GSM shield was used to send the information to the web each time a measurement was recorded. A GSM shield connects to a phone network (similar to your cell phone) and does not require a local internet connection to establish it’s own connection with the web, therefore it was used instead of a Wi-Fi shield so that we could install the sensor out in the wilderness away from any reliable Wi-Fi network.

Materials Used

• Arduino Uno
• Arduino GSM Shield
• Shinyei PPD42 Dust Particle Sensor
• Voltaic V44 Battery (see V50 USB Battery Pack)
• Voltaic 9W Panel (x2)
• Nanuk 904 Waterproof Case
• 8 Pin Male/Female Waterproof Connection Cable
• PG7 Cable Gland (for waterproof opening in Nanuk Box)
• Software: Arduino sketches for Xively and Dweet

Electronics

As the heart of the entire project, it’s important that we make sure the electronics are working properly before we assemble anything else. The GSM shield stacks right on top of the Arduino and the 3 default pins of the dust sensor plug right into the GSM shield.

The dust sensor has a red power wire, a black ground wire, and a yellow data wire to communicate the detection of particles smaller than 10 microns in diameter. While this is fine for some air quality applications, we wanted to be able to determine the levels of dangerous air pollution, which the CDC defines as pollutants smaller than 2.5 microns in diameter (known as “Fine Particles”).

The dust sensor is capable of distinguishing between the two sizes, but only if another wire is soldered on to the connection pad. The original yellow wire will continue to detect pollutants between 1-10 microns, while the additional blue wire will detect “Coarse Particles” between 2,5-10 microns. By subtracting the coarse particles from the overall particles, we can determine how many fine particles are present in the air.

Solder an additional wire to the sensor’s connection pad between the red and black wires without accidentally touching any of the other exposed metal leads. The exposed wires can be insulated from each other with a bit of hot glue.

Picture courtesy of Matthew Schroyer at MentalMunition

Purchase a SIM card with a data plan from a local cell network (we went with T-mobile) and plug it into the GSM shield. Modify Voltaic’s Arduino sketch to include your own “thing name” (without any spaces) to upload data to the Dweet.io server. Finally, upload the code to the Uno and “follow” your device  to see the results in real time.

NOTE: When you modify the code to suit your own purposes, make sure there are no spaces in either the thing name or the data names that are sent to Dweet.io.

Power Conservation

For solar powered projects, reducing the power consumption of the system is absolutely essential. On cloudy or stormy days (or weeks!) the system will run exclusively off of its batteries, so every reduction in power consumption has a very tangible impact on how long the system will run. We learned a lot about reducing the Arduino’s power consumption from this Adafruit tutorial, and used pieces of their code to put our Arduino into Sleep Mode between data readings to save power.

This was more complicated than expected, since the dust sensor does not take an instantaneous reading when it wakes up but must “count” the pollution that enter into it and averages that count over a specified time interval. The Shinyei corporation says it must be on for at least 2 minutes for the sensor to warm up (there’s a small resistor that creates an internal air flow from the heat that emanates from it) so the first sensor reading may not be reliable. We found the actual warm up time to be closer to 30 seconds. This means that in order to get reliable data, we have to record several data points every time the Arduino wakes up from sleep mode.

Even after putting the Uno to sleep we were only able to reduce the power consumption by about 33%. This translated to 50% longer run-time with the same battery which isn’t too shabby. With improved hardware that naturally uses less power, we predict we could at least double the battery run-time compared to the original design.

If you are interested in putting your own Arduino into Sleep Mode, download Voltaic’s Arduino sketch with all the required code snippets for putting the system to sleep and waking it up again when necessary.

To actually power the Arduino, plug the USB-to-Serial cable into the USB port of our battery and confirm the battery is in Always On mode so that it will recover if it looses power.

Weatherproof Hardware

Since we wanted to install this air quality sensor outdoors for months at a time to show the robustness of our solar panels, it is important to enclose all the sensitive electronics in a waterproof case to protect them from the elements. The solar panels on the other hand are built for this type of outdoor use, as the panels and wires are extremely reliable outside in all seasons.

Of course the air quality sensor must be outside exposed to the open air, but it is not waterproof itself so it had to be sheltered from rain while still able to intake the surrounding air. We accomplished this by hacking together a small upside-down box to act as a permanent umbrella that is completely open on the bottom to allow adequate air flow into the sensor.

To see how we hacked together a Nanuk case to store all the electronics, check out this guide to making a waterproof case for Arduino sensors. As you can see from the water drops and the snow on the top of the case, the case has experienced heavy rain and snow over the last few months and it’s held up perfectly fine.

Solar Power

We’ve written before about how to power an Arduino from solar power, and we used some of those principles when deciding what battery and panel size to use for the system. We experimentally determined that the systems runs for about 18 hours from a standard V15 battery, so we upgraded to a V44 battery with more than twice the power as the V15 to last us at least a day and a half without solar power (enough for a full 24 hours of rain/clouds plus the following evening before the sun rises in the morning).

We knew we would need adequate solar panels to power the V44 on daily basis. The system burns about 16 Watt-hours of power per day, so conservatively speaking we need to generate about 32 Wh of power during daylight hours alone. This calls for at least a 6W panel, but since this is still a proof-of-concept prototype we tripled that requirement to be sure it would receive adequate power even in low-light conditions. We installed 2 9W panels in parallel for a total of 18 Watts, generating about 100 Wh’s of power per day when the sun is shining. That’s more than enough!

Posting to the Web 

Now that your system is assembled, it’s time to post your data to the web. We used the data sharing platform Dweet.io for this project because it’s easy to set up (no user account or access keys required) and its visualization platform Freeboard provides a dynamic user interface. We’ve also posted this data to Xively in the past, and have included the code necessary to use Xively next to the Dweet.io code.

Using the raw data uploaded to Dweet.io, here’s another example of what our customized Freeboard dashboard looks like:

As you can see there is a very rich user interface, complete with line graphs, gauges, maps, indicator lights, and even your own original HTML if you have another application you’d like to add.

We spent an afternoon walking around Brooklyn to test out our air quality sensor and see which areas of town were more polluted than others. To see our results, check out the overview post about the results of the project.

Concluding Thoughts

Unfortunately the actual sensor values are not precisely calibrated (it would require much more precise equipment running in parallel with our sensors to calibrate if the data readings were accurate), but they are still useful for observing the qualitative differences between multiple locations. Therefore we can reasonably say for instance, “the inside of this building has 3 times more pollution than the air outside” or vice versa.

Overall this project shows the power and robustness of the Voltaic solar panels for outdoor microcontroller applications. We’d like to thank Nick Johnson for all the work he did on this project, and indirectly thank all of the blogs and websites that helped us with our research about this topic. If you’d like to receive help and support on your own solar powered microcontroller project then absolutely give us a call or send us an email, we’d be happy to help.

References

• Nick Johnson’s Blog
• United States EPA Air Standards compared with International Air Standards
• Matthew Schroyer at Mental Munition for explaining the different channels of the dust sensor
• Chris Nafis at HowMuchSnow for sharing his dust sensor counting algorithm
• Tony Dicola at Adafruit.com for explaining Arduino’s Sleep Mode
• Tracey Allen at TakingSpace.com for deconstructing the dust sensor

This post outlines the steps necessary to build your own waterproof case for solar Arduino (or Raspberry Pi) projects that you want to leave outdoors. We’ve already done several posts about making simple waterproof cases for batteries and personal electronics, so feel free to consult those if you won’t be working with microcontrollers and sensors outdoors. If you’re new to solar powered microcontroller projects, check out our guide to picking the right gear for solar Arduino projects.

Waterproof Case for Solar: Why?

The challenge associated with making a weatherproof box for Arduino projects is that you’ll be using sensors that are waterproof, but batteries and Arduino boards that are not. So how do you leave the sensor exposed to the elements to do it’s job, while simultaneously protecting the sensitive electronics? How would you supply power from inside the waterproof case to the sensor while relaying the information from the sensor back to the Arduino? Great questions, let’s begin!

As an example, we’ll be highlighting the box used for the Solar Powered Air Quality Sensor, which requires 6 wires going in and out of the case (two power wires going into the case from the panel to charge the battery, two power wires going out of the case to operate an air quality dust sensor, and two data wires going back into the case from the sensor to relay information to an Arduino). The wires need to be insulated to travel into the case without compromising the integrity of the water-tight seal. Do we really need to make 6 different entry points?

The solution involves building a single water-tight entry point for all of the power and data lines to travel in and out. This is accomplished using a single multi-pin waterproof connector that can support both power and data lines. For the last two microcontroller projects we’ve done here at Voltaic (the air-quality dust sensor and solar powered weather station) we used an 8-pin male/female waterproof connector with a waterproof plastic cable gland.

Step 1: Assemble Equipment

Project Materials:

• Nanuk 904 Case
• 8 Pin Male/Female Connection Cable
• PG7 Waterproof Plastic Gland

Project Tools:

• Power Drill
• Soldering Iron
• Heat Gun, hair dryer, or handheld lighter for heat
• Epoxy, Silicone, Hot Glue, or other adhesive
• Knife, scalpel, or scissors
• Heat shrink tubing

Step 2: Make a Plan for the Internal Layout

The Nanuk 904 case is an excellent weatherproof box to use in rugged outdoor environments. It comes with a solid foam insert that can be customized to provide a snug fit for all of the devices you want to store. Of course you could always remove the foam insert altogether and have a hollow case, but customizing the foam doesn’t take too much effort so feel free to give it a try.

Begin by laying out all the items you want to store in the case on top of the foam to see how they’ll all fit together. There are small square cut-outs in the foam that are very easy to remove if you have a sharp knife. If possible, keep at least one layer of foam around the perimeter of the box so the electronics are cushioned against hitting the side walls.

Keep in mind where you’ll want the hole drilled in to the case and how that will relate to the items inside, as the first few layouts you come up with may not allow for a convenient hole location. You’ll want to pick a location for the hole that is completely flat so you’ll have a tight seal with the plastic gland.

Once you’ve decided where you want the items to go, remove all of the foam necessary for those items. Remove foam deep enough into the case so that the top of the items are right at the surface of the original foam, that way they’ll be cushioned from the top as well. Remember to cut out room for the wires between the devices too.

Step 3: Drill into the Case

Mark a flat spot on the outside of the case that you want to drill into. Wires will eventually flow through here, so pick a place that allows the wires to flow towards the right electrical device as conveniently as possible, so that they aren’t bent in strange directions if they don’t have to be.

A 7/16″ drill bit would be ideal, but if you don’t have that you can approximate it with the drill bits you do have. It doesn’t need to be a perfect circle, as the epoxy or glue will make up for any imperfection when creating the seal. Just make sure it’s large enough to fit the gland through while having a snug fit on it.

Step 4: Attach the Plastic Gland

A plastic glad is a great tool for creating an watertight seal when prototyping projects because it gives you the flexibility to change your mind and move things around. Don’t buy a plastic gland until you know what connecting wire you’ll be using, that way you can select a gland with an appropriately sized range of inner diameters to fit the wire.

There are 4 main parts that work together to create the seal, including a rubber o-ring (not pictured). The central piece in the middle is what the large wires flow through, the “fastening nut” on the right of the middle picture is what secures the gland to the case from the inside, and the larger “tightening nut” on the left is what tightens the gland around the wire to create a water-tight seal.

Step 5: Apply Sealant

Before you screw the gland onto the outside of the box, be sure to place the rubber o-ring in-between the gland and the case. This helps to create a water-tight seal between the gland and the case, so be sure to tighten the gland down as much as necessary to make sure water can’t slip past the o-ring.

Depending on the quality of the hole you drill and the flatness of the side wall of your case, you might not create a water-tight seal from the o-ring alone. There may be some small imperfections that allow drops of water to creep in through the threads of the gland that seep into your case. This can be easily prevented with any good sealant, such as epoxy or a hot glue gun or sealing silicone, all of which can be picked up at a local hardware store.

Question: If the gland isn’t water-tight, why use it at all? Why not use only sealant that attaches to the wire itself?

• Great question. The benefit of the gland is that it grants you far more flexibility with modifying the cable that goes into the case. You can push the cable in or out to get the best fit with the other electronics as you change things around, or you can swap it out altogether with another cable if you want to reuse the case for another project. Though if you don’t plan on reusing the case and you don’t need to pull out or rearrange the cable for any reason, feel free to ignore the gland and drill a hole only large enough for the cable, then use sealant over the cable itself at the entry point to make it water-tight.

Put a full ring of your sealant around the edge of the case where it connects with the gland. Tighten the gland around the sealant and make sure it completely covers the base of the gland. Give it sufficient time to dry and set into place before twisting it around or attaching the tightening nut around a cable.

Step 6: Wire Preparation 

Now that your case is ready, you’ll need to prepare the wires on the inside and outside of the case. This involves soldering and heat-shrinking tubes, so be sure to make a plan before you begin! You’ll need to decide how to color-coordinate the wires of the 8-Pin connection cable, and how you’ll insulate the wires from each other so they don’t short out (remember to put them on before you begin soldering!).

Important points to remember:

• It doesn’t matter if the male or female side of the 8-pin connector is connected to the case or on the outside
• Maintain the same wire color coordination on the inside and outside of the case
• Place the shrink wrap tubing on each wire BEFORE  you begin soldering, and make sure it’s far enough away from the exposed leads that when they heat up, they won’t shrink onto the wire before you want it to
• Place the tightening nut on the cable BEFORE you feed wires through the plastic gland and solder them
• Insulate the 8-pin connector where the exposed wires connect to the sensor and power wires, that way water can’t seep through the cable on the inside

Sensor Wires: All four wires coming from the sensor need to be soldered to individual wires of the 8-Pin connector (as you can see from the upper-left picture). Luckily the colors of the sensor wires matched the colors of the connector, so we maintained that color theme to avoid confusion. Each wire needed it’s own insulation to prevent the data signals from being disturbed and prevent a short circuit. Try to do as much soldering as possible before the cable is fed into the plastic gland, that way it will be easier to control before it’s in a confined space inside the case.

Solar Wires: We need to attach the power wires of the solar panel to both the male and female sides of the 8-Pin connector to recharge the V44. While you could cut the adapter plug off of the panel cable itself and hack those wires to the connection cable, we chose instead to install a waterproof female port from one of our extension cables so that we wouldn’t have to modify the panels at all. This gives us more freedom to change the size of the panels if we want, or use additional extension cables if we want to separate the panels from the case. Likewise on the inside of the box, we soldered a generic power extension wire so that we could attach any adapter we want and have the freedom to change batteries in the future. The power cable for the battery wouldn’t fit through the plastic gland (as you can see, it’s missing from the lower-left picture), so it needed to be soldered after the cable was fed through the entry point.

Finally when all of the outside wires are soldered and insulated individually, use one large insulating shrink-wrap tube around the collection of wires and place a little extra sealant where they all join together so that water can’t enter into the inside of the cable.

Step 7: Test Your Work – Full Submersion Test

Once all the cables are soldered and fed through the plastic gland, you can screw on the tightening nut as tight as you can with your fingers (and maybe a little bit more with a wrench if you have one) and you’re finished! Any good engineer will test his work before he puts it out in the wild, and the best way to do that is a full submersion test. Empty the case and insulate the top of the 8-pin connector so it doesn’t get wet during the test, then place the case completely under water for a significant period of time (10 minutes or more). If no water seeps through to the inside of the case, you’ve done a great job!

Confirm that the power and data wires are working properly, and you’re all done.

Result

After combining this case with two 9 Watt solar panels, we placed it up on the roof to start recording air pollution. Over the last few months it’s experienced heavy rain and several inches of snow while keeping the equipment on the inside perfectly dry.

If you have any questions about how to use a waterproof case for your specific setup, be sure to give us a call or send us an email. We’d be happy to help you get your microcontroller project up and running.

This project is in response to a number of customers who’ve asked us about using solar to power their IOT sensing projects and then publish their results in real-time to the web. This Arduino Spark Core Weather Station project publishes the data via WiFi and future projects will do so via GSM. The code for this tutorial and initial testing was done by Max Henstell @mhenstell and http://kapamaki.net/

The parts are:

• Voltaic 9 Watt Solar Charger Kit ($85)
• 4 Foot Extension Cord ($6)
• Spark Core (with external antenna connection) ($39)
• SparkFun Weather Shield ($40)
• SparkFun Weather Meters ($69)
• 11 Female to Female pin jumpers ($25)
• Parts for the Solar Battery Case ($20-$35)
• uFL to RPSMA Adapter ($4)
• External WiFi Antenna ($7)

13/64”, 3/8”, and1/4” drill bits (or close, doesn’t have to be exact)

We put the guts inside of a modified weatherproof case similar to the setup in our battery case tutorial. For this build we used a Nanuk 904 case that was modified with an 8-pin waterproof plug, and a waterproof plastic cable gland sealed with silicone.

1) Start by soldering the right-angle headers onto your SparkFun Weather Shield. You can solder them to every hole if you’d like, or just the ones we need (see the table below).

2) Next, we’ll need to solder two “pull-up” resistors to the I2C data lines (the pins labeled SDA and SCL). I’ve soldered them to the back of my shield. The resistors connect the SDA and SCL pins to the VIN (or voltage-in) pin. Make sure you don’t short the SDA and SCL lines together.

3) Using the female-to-female pin jumpers, connect your weather shield to your Spark Core. The wires should be connected like this:

4) Time to set up your Spark Core and test it out! Plug your wind and rain sensors into the weather shield (follow the markings on the board) and follow the instructions on Spark’s website to set up your Spark Core. Remember your Spark username and password, you’ll need those to sign in to their website to upload code. (Note: if you have difficulty connecting to your Spark Core, try another WiFi network, and follow the detailed instructions on their website). Note: new Spark Cores are black, but otherwise are exactly the same.

5) Now you should be online with your Spark Core, and ready to load the software for driving your weather station. Open the Spark web IDE and enter the account information you created earlier to get started. You should be greeted with a page that looks like this:

Name your app (I used “My Weather Station”). Open this code for the weather station, and copy and paste the whole document into your new app in the Spark IDE, replacing the starter code that came with it.

You’ll also need to include a few community libraries. Click the libraries button on the left, and using the search box, find the ONEWIRE library. Click on ONEWIRE, then click “Include In App,” select your app, then click “Add To This App.” Do the same for the HTU21D and ADAFRUIT_MPL3115A2 libraries.

6) Next, sign up for an account on ThingSpeak. This is where we’ll be posting our collected weather information. Click “Create New Channel” and fill out your channel’s information. Enter the following information in your channel fields:

7) Next, on ThingSpeak, click the API Keys tab. Copy your Write API Key. You’ll need to put this into your Spark app to be able to talk to ThingSpeak. Go back to your app in the Spark IDE and find the line near the top that says String writeAPIKey. Paste your ThingSpeak Write API Key (the key pictured is inactive) between the quotes, then save your code by clicking on the folder icon.

8) You’re now ready to upload your code to your Spark Core! Flash your code by clicking on the lightning icon. You should be prompted to select which Core you would like to flash. Select the Spark Core you claimed in the above step. Your core should start blinking purple. When it’s done uploading, your Core should reconnect to the Internet and start pulsing cyan. Wait a minute for your code to start sending data, then refresh your ThingSpeak channel. You should see a new data point!

9) After you’ve amassed some data, go to your ThingSpeak Private View page, and click the edit icon (it looks like a pencil) above any of your graphs. Here you have different options for how your graph is displayed. Here, I set the Average to 10 and the Results to 500, this gives me a smoother line going back to this morning:

10) Time to put it all together and stick it outside! First, you’ll need a weatherproof enclosure. Follow our battery case tutorial to get your enclosure started. For the weather station, we’ll also need to get two RJ11 (phone line) connectors into the box, for our wind and rain sensors. Unfortunately, unlike the power cable, phone cables are a pain to chop and re-connect, and crimping a replacement connector requires a special tool. Since there were eight wires we decided to use a waterproof 8-pin plug. It takes a little extra soldering but it’s well worth it to be able to separate the sensors from the enclosure.

We drilled a 7/16″ hole in the side of the case to to accommodate the gland and connector. Once inside, we applied silicon around the base and tightened it down with a crescent wrench.

11) Once you pass one side of the connector through the enclosure you have to solder everything together; do the same for the wires going to the weather station sensors. On the inside and outside pieces we covered the tips in heat shrink tubing for more insulation, and on the outside we used large diameter heat shrink as well as wrapping it all in electrical tape. We also added a separate hole for our external antenna. The external antenna will help with reception if you plan to mount the box on your away from your access point. If you go for the Spark Core with the built-in chip antenna, you don’t need to drill a separate hole for an external antenna.

You can follow my diagram below. !!!NOTE!!! Your wire colors may vary depending on the manufacturer of your RJ11 and your 8-pin connector.

11) Plug your Voltaic solar panel and Spark Core into your Voltaic battery. If it’s sunny, you should see the battery charger indicator start to light up. Next, hold down the power button for six seconds, until you see the LEDs flash three times. This is “Always-On” mode, meaning even if the battery goes flat it will automatically start supplying power to the sensors once the sun comes out again.

That’s it! Enjoy your new Voltaic Systems solar-powered weather station!

You can view the weather conditions on our ThinkSpeak channel here: https://thingspeak.com/channels/15062 The channel’s measurements are off due to some limitations with ThinkSpeak… but you can see that it is sensing and running from solar only.

Here are a couple photos of our station in wild ole Brooklyn!