Parts
Node: RAK WisBlock Meshtastic Starter Kit SKU 115017 Meshtastic Starter Kit | The Basic Meshtastic Kit for LoRa
Temperature and humidity sensor: RAK Temperature and Humidity Sensor Sensirion SHTC3 SKU: 100001 Temperature and Humidity Sensor | Temperature Sensor | SHTC3 Sensor
Current and voltage measurement device: DC Current Sensor 3A Texas Instruments INA219BID RAK16000 WisBlock Interface Module | Wireless LoRa/ LoRaWAN Current Sensor
Antenna: Alfa Network LoRa/HaLow 868MHz Antenna 5dBi N-Male Connector AOA-868-5ACM Alfa Network Alfa LoRa/HaLow 868MHz Antenne 5dBi N-Male Stecker AOA-868-5ACM: Amazon.de: Computer & Zubehör
Antenna SMA adaptor and bulkhead mount: TUOLNK N Female to SMA Male 4 Hole Flange Plate Connector TUOLNK 2er Pack N Buchse auf SMA Stecker 4 Loch Flanschplattenstecker Typ N auf SMA RF Koaxial Lötstecker Chassis Montage Koax Adapter: Amazon.de: Elektronik & Foto
IPEX to SMA connector (x 2): Hailege IPX IPEX-1 U.FL to SMA Female Pigtail Antenna Hailege 5pcs IPX IPEX-1 U.FL zu SMA Buchse Pigtail Antenne Wi-Fi Koaxial Low Loss Kabel 6 Zoll (15cm) : Amazon.de: Elektronik & Foto
Bluetooth antenna: KHIYQILO WiFi Antenna 2.4GHz 3dBi SMA Connector IPEX Bluetooth KHIYQILO WiFi Antenne 2.4GHz 3dBi SMA Connector IPEX Antenne für WiFi Router Drahtlose Netzwerkkarte Sicherheit IP Kamera Videoüberwachung Monitor Bluetooth Antenne: Amazon.de: Computer & Zubehör comes with all the parts needed to fix it to the box
Battery solar charger: Hailege CN3065 Mini Solar Lipo Charger Hailege 2pcs CN3065 Mini Solar Lipo Ladegerät Board Lithium Batterie Ladechip Micro USB DIY Outdoor Application Kit Ladebrett Modul : Amazon.de: Elektronik & Foto
Battery: (I tried this battery but it did not seem to work, EREMIT 3.7V 10.000mAh LiPo Battery Order number 1260100
(Connector JST-PH 2.0 mm) EREMIT 3.7V 10.000mAh High Capacity LiPo but provides super long battery life if charging from USB only without solar….) so I went with a 2000 mAh one Lithium Ion Battery - 3.7V 2000mAh : ID 2011 : Adafruit Industries, Unique & fun DIY electronics and kits
USB C port: PENGLIN 2pcs Type-C Female Panel Mount Connector, Aluminium Alloy USB 3.1 Feed Thru Coupler Female to Female Module Converter with Dust Cover PENGLIN 2PCS Typ-C Buchse Panel Mount Connector, Aluminiumlegierung USB 3.1 Feed Thru Coupler Buchse zu Buchse Modul Konverter mit Staubschutzhaube: Amazon.de: Elektronik & Foto or similar
Box: Waterproof Junction Box, IP65 Electrical Project Box, Distribution Box, Dustproof, Weatherproof, ABS Cable Housing Distribution Box for Indoor Outdoor Electronic Cable (Transparent 20 x 12 x 7.5 cm) Wasserdichte Anschlussdose, IP65 Elektrische Projektbox Verteilerdose Staubdicht Wetterfest, ABS Kabelgehäuse Verteilerkasten für Indoor Outdoor Elektronikkabel (Transparent 20X12X7,5CM) : Amazon.de: Baumarkt or similar such as RND 455-01406 - Plastic Enclosure with Clear Lid Universal 180x120x60mm Light Grey Polycarbonate IP66 / IP68 / IK07, RND RND 455-01406 | RND Plastic Enclosure with Clear Lid Universal 180x120x60mm Light Grey Polycarbonate IP66 / IP68 / IK07 | Distrelec Germany
USB micro port: QIANRENON 90° Right Angle Micro USB Panel Extension Cable Micro USB 5 Pin Male to Female Car Boat Motorcycle Dashboard Extension Cable 28cm (Right Curved Plug) “see-QIANRENON 90° rechtwinkliges Micro-USB-Panel-Verlängerungskabel, Micro-USB, 5-polig, Stecker auf Buchse, für Befestigung am Armaturenbrett von Auto, Boot, Motorrad, 28 cm (rechts gebogener Stecker) : Amazon.de: Auto & Motorrad”
JST 2.0 PH Connectors: GTIWUNG 20 Pairs JST Connectors, JST 2.0 PH 2 Pin Connector Plug, 2-Pin Connector Plug Male & Female, JST 2.0 mm 2-Pin Plug with 80 mm Cable Wire GTIWUNG 20 Paare JST Steckverbinder, JST 2.0 PH 2 Pin-Verbindungsstecker, 2-Pin Connector Plug Male & Female, JST 2.0 mm 2-poliger Stecker mit 80mm Kabeldraht : Amazon.de: Spielzeug
Heat shrink tubing for the above wires when soldered together - very small diameter e.g.
Solar panel: Solarzelle - 2W, 6V, 11.0 cm * 13.6 cm Solarzelle - 2W, 6V, 11.0cm*13.6cm gĂĽnstig online kaufen | Funduinoshop
I think it needs one of these pressure equalisation plugs but I skipped that EVPS 12 BLACK | WISKA LTD Pressure Compensating Plug M12 12mm IP68 / IP69 Polyamide 6 Black | Distrelec Germany
Thermal switch: Bimetallic Thermostat switch for 55 degrees C sourcing map 10 StĂĽcke Temperaturschalter Thermostat Bimetall 55C Normal Geschlossen KSD9700 : Amazon.de: Baumarkt
Small nuts and bolts to mount LoRa antenna (M4 is best): Connex Gewindeschrauben-Sortiment 275-teilig - Diverse Größen - Rundkopf - PH Phillips-Antrieb - Vollgewinde - Verzinkt - Inklusive Muttern / Schrauben-Set / Sortimentskasten / DP8500055 Silber : Amazon.de: Baumarkt
Some waterproofing might be useful: Sika – Dichtstoff – Sikaflex-291i Schwarz – ideal für den Marinebereich – hochelastisch und überlackierbar – geruchsarm – 70 ml : Amazon.de: Baumarkt and PTFE plumber’s tape 1 Rolle Teflonband Gewindedichtband 12 Meter PTFE 12 mm Dichtband : Amazon.de: Baumarkt
A cable tie and small screws to screw down parts in the box if needed: I used SPAX 2.5 x 10 Z1 SPAX Universalschraube, 2,5 x 10 mm, 100 StĂĽck, Vollgewinde, Senkkopf, Kreuzschlitz Z1, S-Spitze, YELLOX - 4081020250102 gĂĽnstig bei rubart.de screws x 3 but others might be better
Tools
Step drill (Stufenbohrer) such as Flintronic HSS Stufenbohrer, Sechskantschaft-Stufenbohrer-Set, Kegelbohrer Holz, Professioneller Stufenbohrer 3-teilig 4-12/4-20/4-32 mm FĂĽr Metall, Messing, Holz, Kunststoff, Silber : Amazon.de: Baumarkt
3.5 mm drill for the 4 m screws to mount the LoRa antenna.
6.5 mm drill for the hole for mounting the Bluetooth antenna.
Soldering iron and solder, small spanners.
Build
To build, just drill the required holes and mount the antennae. Fix the RAK board and battery somehow. Images show the wiring clearly enough hopefully.
The voltage and current measurement wiring is shown here
The node has so far always re-started on solar power if left to run flat deliberately. The node reports the solar panel voltage and current. It has a 55 deg C cut-off for the battery. A long-term test is running to see if it survives when mounted vertically in sub-optimal location in winter….
Node short name: MRbo
Electrical details of the battery solar charger
The solar charger uses this chip described here https://raw.githubusercontent.com/SeeedDocument/Lipo_Rider_Pro/master/res/DSE-CN3065.pdf , and appears (not sure) to be based on a design listed here GitHub - IOT-MCU/Solar-Charger-v1.0: Solar Charger v1.0 if this video CN3065 18650 Li-ion Mini Solar Charger Module - ThinkRobotics – ThinkRobotics.com is anything to go by, which appears to describe the same device and names the manufacturer as IoTMUC.
Field test results
The node does wake up if there is enough sun but has not yet managed to be on a full day.
The node lost its settings completely (reverted to factory settings) one time after being off due to empty battery and then slightly charged to about 3 %.
The location is such that the node keeps running flat in the evening: this tests the re-start capabilities of the circuit I am using.
Update: the node was once not able to restart autonomously despite there being sun. The Hailege CN3065 Mini Solar Lipo Charger that I used in the manner above was able to go into a mode that the device was after brownout no longer able to restart, though sometimes it did restart. UPDATE: I tried to re-start the node when wired as shown above when it had entered a permanent shut off mode that would not re-start. The restart button did not start the node. Plugging in USB C power did not restart the node, but only illuminated the charge light. The only thing that re-started it was disconnecting the “sys out” connector on the solar board and re-attaching it. Then the node woke up and was able to draw on the battery which had charged from the sun to about 40% all the while the node was locked in shutdown unable to wake up of its own accord.
But now I realise that this circuit will not wake up guaranteed I am moving to this design RAK 4631 Solar Repeater - #83 by smurfy which works fine so far but is still being tested. I may also test this CN3065 iHaospace CN3791 Lithium Battery Charging 3.7V 4.2V MPPT Solar Panel Regulator Controller Module 12V: Amazon.de: Computer & Zubehör and the Adafruit board Adafruit Universal USB / DC / Solar Lithium Ion/Polymer charger [bq24074] : ID 4755 : Adafruit Industries, Unique & fun DIY electronics and kits