Ultimate Off-Grid Meshtastic Node

Meshtastic is designed for off-grid communications, and as such it's to be expected that nodes will be taken to remote locations, where they will be exposed to rough handling, inclement weather, and infrequent -- or nonexistant -- opportunities to recharge from a power grid.

Therefore, it's important for nodes to be rugged, dust and water resistant, and capable of operating for long periods without the need to be recharged from an outlet.

Unfortunately, despite being an affordable alternative to Gotenna and Beartooth, there are virtually no Meshtastic devices designed to withstand off-grid use.

"The ultimate off-grid Meshtastic node" is a phone-sized node that's ruggedized, water resistant, self-sustaining with a built in high efficiency solar panel, and has a generous 2, 500mah battery that -- drumroll please -- can serve as a 5v solar power bank to charge other devices in a pinch (including other nodes)!

Since the node can power itself indefinitely, it can be left in a fixed location as an impromptu repeater to extend the range of ground teams during disaster relief, search and rescue, and humanitarian missions.

The list of potential users is long: non-profits, volunteers, NGOs, international relief organizations, developing countries...anyone who needs off-grid location and communication services in a remote or disaster impacted location.

This node, despite its compact, smartphone-sized footprint, sports enough room for a full size 25mm GPS patch, which will help you stay connected even under dense foliage, inside buildings or vehicles, and under heavy cloud cover.

Moreover, this one system works for all three Tracker L1 devices; you'll simply change the faceplate! (actually, the L1 Lite's faceplate has a punch out, so it can simply be converted to accept the OLED screen)

That unrivaled versatility will be welcomed by users who upgrade their device by adding a screen or upgrading from the OLED to E-Ink.

There's also a lot of room for expansion. For example, optional faceplates can expand the battery capacity to 10, 000mah with only a marginal sacrifice in weight and dimensions. In a larger format, it could be a very formidable power bank, or run for very long periods of time in locations where the sun is scarce, such as near the poles.

Perhaps best of all, the DFM (design for manufacturability) is highly optimized for the casual 3d printer. It can be printed on virtually any printer with nearly any filament with no special settings, no supports, no post processing, etc. Just slice it, rip it off the print bed, and assemble it!

It also requires virtually nothing in the way of special hardware or tools. In fact, it doesn't specifically require any hardware or tools at all! If hardware isn't available, you can simply super glue it together!

Last but not least, the case has unrivaled versatility. It can accommodate a wide range of batteries and boost boards, and gives full access to the connector ports on the Tracker's board so plug-and-play components can be used.

I'm also working on an optional cover that will have a small keyboard built into it (just waiting for the keyboard components to arrive in the post).

Housing prototypes:

Prototypes have been printed and assembled with the E-Ink version, and the design is proving to be very sturdy and user friendly.

Experiment to evaluate viability of solar charging:

The experiment was conducted in downtown OKC on the 24th of August, starting at 10am central time. The battery had been allowed to run down to dead (which took approximately 72hrs from full charge), and the battery's protection circuit kicked in at 3.25v, and the device lost power.

As soon as the solar panel was placed in partial sun, the device powered on (heard power chime and noted blinking LED indicating device is on), and the partial morning sun was producing enough wattage to power the device and initiate the charging circuit (as seen by the solid red and green lights indicating external solar power), and the battery leads read 3.66v).

Messages were successfully sent to the local mesh, and quickly acknowledged by the OKC Downtown repeater. This fully confirms that the solar panel is capable of powering the device in average conditions, such that messages can be sent even if the battery is completely dead.

The conditions for the test were on the poor side of average, with partial sun in the early morning and cloudy conditions for the afternoon, when the sun was at its highest point.

As you can see, the results are very promising! This is with a 1.2w, 20% efficient panel that costs $15 USD retail, and there are currently commercially available panels up to 30% efficiency (albeit at higher prices). So, currently available cost effective panels are very useful, and even more capable panels are guaranteed to be available at lower prices soon, meaning this concept is fully viable at present, and will only continue to become better in the near future with subsequent generations!

We got some sun today later in the evening, so I took the opportunity to see how fast the battery can charge in good conditions. I turned off the power, and let the solar panel recharge the battery for a few hours. This was in the waning evening sun, as it was overcast during mid day, but the results are still very promising!

Considering this panel is only 20% efficient, the buck/boost board is a cheap, inefficient one, and the weather wasn't ideal, this test proves the viability of the design. Even under less than ideal conditions, using less than ideal components, the solar panel provides very significant power to the device, and does so without increasing the form factor to any significant degree. Remember, this is a 2500mah battery, so that translates into approximately 150mah of charge in just a few hours of waning fall sun. In conclusion, this setup has the potential to be completely autonomous, depending on solar conditions and traffic, and one could very realistically deploy this as an emergency router and simply leave it on a nearby peak or rooftop, as well as have it double as a backup power bank and solar charger for other devices, making it an extremely versatile node.