Rak Unify Solar Enclosure
Rak Unify is a very well-designed weather-proof solar enclosure, designed for the Rak line of modular hardware components.
Even though I haven’t ported the ChatterBox firmware over to Rak’s hardware, I very much wanted to try out this enclosure, and see if it can keep ChatterBox nodes charged and protected.
The Solar Panel
It’s easy to throw a bunch of components into a solar enclosure and then call it a “solar node”. However…can the unit remain charged? That’s the question I needed to answer.
The ChatterBox node firmware needs somewhere between .02 and .03 amps consistently, to run on the ESP32 or SAMD51 platform. During transmissions, it will spike to .06 - .07 range for less than a second.
There are ways to reduce that somewhat, such as disabling the display (which can be done remotely), but still it’s going to need over .02 amps constantly to avoid going into low-power mode.
If that seems like a lot, consider what the firmware is doing:
Listening for pings/packets 24/7
Sending signed/encrypted pings every 40-90 seconds
Propagating encrypted mesh connectivity and location data
Assisting in mesh deliveries
Reading / writing to SD, FRAM, or Flash storage
I grabbed a Rak enclosure and took an amp reading from the solar panel (it’s still winter & cloudy today). The highest reading I saw within about a minute was .034 amps.
It appears there’s often not an overabundance of output to both run the node & charge the battery, but my testing reveals the setup actually does just fine.
Building a Node
I won’t go into great detail on the build here, since you can download the build instructions as a PDF. However, here are the components I used:
Rak Unify Enclosure
Lilygo T3S3 SX1262
DS3231 Realtime Clock (instead of GPS)
DFRobot Charge Controller
5000 mAh LiPo Battery
The components fit pretty well. Instead of the Rak-inclued SMA connector, I bought an all-weather enclosure SMA connector from Amazon (see build instructions), because the T3S3 has a nice soldered SMA connection instead of a wimpy pigtail.
Other than that, I pretty much just wired things together as described in the build instructions.
Results
The node has remained outside in the rain, ice, sun, and whatever else goes on out there for the past 3 weeks.
ChatterBox has the ability to securely issue encrypted remote commands via mesh, so I have used that capability to remotely monitor connectivity and battery strength. The node has been running flawlessly and non-stop for the entire period.
Every day by noon, the battery level is at 100%, even on days when the sky is overcast.
I checked again just now and took a few pics, and you can see the node is still sending pings regularly and instantly responds to remote commands. Upon querying battery level, it reported back “100%” within seconds.
The Testing Continues
I continue to let this node run, and will do so all summer and report any new findings.
Since the days are longer with more hours of sunlight, I fully expect this node will continue with no problem.
I am currently moving the node onto a mast where I can set it and forget it for a few months.