Fixed Outdoor Solar Powered Nodes

11/4/24

By:

Jeff Scoville

Fixed Outdoor Nodes

Key Considerations in Proposing a Design

Solar and battery powered
Weatherproof
Durability
Low maintenance
Remote Administration
Minimal Profile
Expandable Functionality

This is the BOM for building a Fixed Outdoor Solar Powered Unit per the "Austin Mesh" standard.

This is what it looks like in real life:

The base RAK board is:

Lessons learned by Austin Mesh and others from using the RAK board:

Don’t trust the RAK board to handle varying solar voltage or varying battery voltage.
Solar panels: bigger is better. 10 watts or more is ideal.
Battery: bigger is better. 5,000 mAh or more is ideal.
Antenna: fiberglass antennas are the most robust and can handle wind, rain, and UV light better than rubber ducky antennas.
Heat can kill the battery – it is best to shade the box containing the battery.
Don’t add any modules.
Waterproof box and all penetrations.

Why a smart charge controller?

Although the RAK19007 includes a built-in charge controller, it has a low charge rate, and the board requires a manual reset if your batteries are drained too much. That's why an additional charge controller is used inside the S4. Under extreme circumstances, if the solar panel does not receive enough light for an extended period of time, the controller will temporarily cut power to the WisBlock in order to conserve battery. Once charging resumes and batteries are brought up to acceptable levels, power is restored to the WisBlock, restarting it automatically. The charge controller is also designed to charge the batteries to around 90-95%, in order to extend the life of the batteries.

Alternatives that were evaluated before making final decision on the "Austin Mesh" build:

Spec 5 Relay

Product	S5 Relay
CPU	32-bit ARM® Cortex™-M4
Flash	256 Kb
RAM	1 Mb
Frequency	915 MHz
Dimms	~16 x 10 x 7 in
Weight	~ 2.5 lbs
Battery	2 x 18650
Antenna	50 cm Outdoor IP67 Waterproof 8DBI WiFi Fiberglass Aerial
Urban Range	~1-3 miles depends greatly on mounting height
Rural Range	~5-10 miles depends greatly on mounting heights
Battery Life	8 hrs active 24 hrs standby
Solar Charging	Active
Solar Panel	12W
Case Material	PETG

Autonomous Operation: Operates as a relay station only. Connect a device via Bluetooth to update settings. A personal LoRa Meshtastic device (e.g., Spec5 Trekker, Spec5 Beacon, Spec5 Copilot, Spec5 MeshClip, Spec5 MiniTrekker) is required for Bluetooth tethering to your phone.

Solar Powered: Powered by a 12 W solar panel and two 18650 LiPo batteries, our relay station operates indefinitely without intervention. The low-power consumption of the LoRa radio, combined with efficient solar charging, guarantees uninterrupted functionality in even the most challenging solar conditions.

Long-Range Transmission: Equipped with a large antenna optimized for long-range transmission, our relay station extends coverage up to 10 miles with line of sight, facilitating robust connectivity across vast distances.

Rugged and Weatherproof: The waterproof enclosure, complete with cable glands, safeguards the radio from harsh weather conditions while allowing seamless passage of wires.

AltaVox S4 Node:

References to article:

https://www.austinmesh.org/

https://specfive.com/collections/relay

https://atlavox.com/products/atlavox-s4-solar-meshtastic%E2%84%A2-node

https://youtu.be/aP4M6W6KtmM?si=ptTFpgzA4U1mpHKf