Devices for the Mesh

Suggested Hardware

If you want to explore ALL of the various options for LoRa devices for use on either MeshCore or Meshtastic, check out RF Index, which easily compares them in detail. This includes DIY, “Off the shelf”, solar, etc.

Companions / Clients

• DIY: Heltec T114 - The official Austin Mesh build from Andy Shinn
• Buy (smallest): SeeedStudio SenseCAP MeshTracker X1
• Buy (better antenna): Atlavox M1

Repeaters

• Best (~$250): Atlavox Beacon
• Good ($75-140): SenseCAP Solar Node P1 Pro
• DIY ($75-200): Build your own — see the parts list below

Building a Solar Repeater

A brief history

History of versions

We have tried 5 permutations of solar powering repeater nodes:

Lessons learned:

1. Don’t trust the RAK board to handle varying solar voltage or varying battery voltage. It is very unhappy if either voltage goes outside of a narrow range. In fact there is a known issue where the Nordic nRF52840 module inside of the RAK 4631 chip causes it to enter a “Super Deep Sleep” fault state when it is supplied with 3.3V. This means when the battery voltage falls too low the RAK chip shuts down and can only be rebooted manually.
2. Solar panels: bigger is better. 10 watts or more is ideal.
3. Battery: bigger is better. 5,000 mAh or more is ideal.
4. Antenna: fiberglass antennas are the most robust and can handle wind, rain, and UV light better than rubber ducky antennas.
5. Heat can kill the battery – it is best to shade the box containing the battery.
6. Don’t add any modules. The GPS module increases battery usage significantly and is unnecessary if the repeater is in a fixed position.
7. Seal everything properly and make sure water has a way to get out of the case. Use o-rings for the antenna mount and wrap connectors in proxicast. Add an air vent plug to the case so any condensation has a way to escape. For high humidity environments, spray the electronics with conformal coating.

These are lessons learned from Austin Texas, where the main environmental stressors are heat and thunderstorms. In the summer of 2023 we 80 days over 100° F (38°C) and we had a stretch of 11 days over 105° F (40.5°C), during which two radios died. We also can have both high humidity and high temperature at the same time in Austin; in the summer the weather would swing from 80° F (27°C) with 85% humidity in the morning to 105° F (38°C) with 25% humidity in the afternoon. Weather history here. Our learnings are probably applicable to other southern and desert climates.

Considerations for other climates

1. Northern Climates and extreme cold
   • This isn’t from our experience, but we felt it was so valuable that we shoud link to it here. YYC Mesh, a group in southern Alberta as well as the Greater Vancouver/Victoria recently published their findings on batteries in cold temperatures.
   • LiPo and Li-ion are fine(0 failures)
   • Capacity IS reduced. 3000mAh minimum kept nodes up and charge rates low(good thing)
   • Charging creates heat, enclosures trap heat
   • nRF52 > ESP32
   • Solar panel angle matters
2. Coastal Climates: salt spray and condensation from fog can kill electronics quickly. In coastal climates it is best to spray the electronics with conformal coating.

MeshCore and Meshtastic Solar Repeater Parts list

With all that said, here is the parts list for our most-preferred way to build a solar powered repeater. This design doesn’t require any soldering or complicated connectors. It also doesn’t require any battery management chips (which often have long shipping lead times and can be hard to get). For this design the solar panel is connected directly to the battery pack via USB. Then the battery pack is connected to the board via USB. The Voltaic Systems V25 battery is nice because it is optimized to charge from a solar panel and it is set standard to an “always on” mode which means the battery bank does not shut off after a set amount of time like other battery packs – this is useful as the RAK chip uses very little power and can trick other battery packs into shutting off. The other really nice thing about the Voltaic pack is than when it drains down completely it shuts down, but then once the solar panel has sufficiently charged it back up it will automatically turn itself back on again. The RAK radio uses between 100 and 1000 mAh per day, with about 400 mAh per day being average so theoretically the 6,400mAh Voltaic V25 could keep the radio running for 16 days without solar.

Standard Parts

RF Filtered Parts

One of our nodes is on top of a building surrounded my 2200w of public service antennas which operate around 850mhz. The result is that the RAK (and any other) board is quickly desensitized. We’ve had the best success doing 2 things. Keeping cable runs as short as possible, and use a notch or bandpass filter.

Aerial Nodes

As you may already know, the mesh technology we use relies on the LoRa technology in the 900mhz frequency range. This means that connection is dependent on Line of Site(LoS) between the antennas. The easiest way to ensure LoS is with height. The easiest (though temporary) way to get height is through an aerial platform including but not limited to UAVs(drones or planes) or kites!

Drone Nodes

In our starting a similar network section we discussed the intentional usage of drones to help grow your network. This section will cover some key tips around hardware, strategy, and safety.

• Schedule: Most drones will only fly for 15-30m per battery. Schedule communication windows specifically so that batteries are not wasted. Consider prescheduling times with your group to either have multiple drones up at once, or extend windows by alternating who is in the air.
• Weight: Due to the short flight times, your node can use a very small battery. Think 100mah. Strip all non necessary items.
• Safety: Fly in open areas. Use minimum height necessary. Make sure the node is secure and can’t tip or the antenna fold which may hit propellers which will cause a crash. Avoid hanging the node unless there is no other solution. Hanging nodes easily swing up and hit propellers.
• Configuration: Use 2 nodes. One on the ground that you connect to with your devices and one on the drone. Set the node on the drone Router or Router Late to ensure messages actually pass through. If set to Client it may not retransmit the packet as it has already heard the packet from multiple other ground nodes. Consider setting the ground node to Client Mute.

Examples

• DJI Air 3 (affiliate link)
• Seeed/XIAO

• DJI Mavic Mini (affiliate link)
• LilyGo T-Echo

Other Examples

Kite Nodes

Read more about our Kite Node operations.