This solar node is for use in the home or when using the car to get a link to a main (Station G2) node in the attic or in the car under the sunroof, because Bluetooth does not reach far enough. The box is waterproof and robust and so can be left within bluetooth range of my phone indoors or out.
The build has the interesting aspect that the parts only just fit inside the box (solar panel and USB charging port and antenna only just fit). The result is a node that cannot have its antenna snap off (it is entirely within the box) and can be charged without having to plug a USB cable into it (but you can if you want, see to end) etc. The battery can run the node for at least three weeks from fully charged. The box has a transparent lid to allow the solar panel to work. The transparent lid means that one can still read off the LED lights of the Wisblock and Waveshare solar power manager board, so you can see, for example, what percentage charge the battery has and whether the solar panel is charging the battery. A fun part is that all those flashing lights (red, green and occasionally blue) make the box a fab and geeky night-light feature. Had I only know sooner how reassuring random flashing LEDs can be…
Parts list:
Radio: Rak wireless WisBlock Base Board 2nd Gen | RAK19007
SKU: 110082
Nordic nRF52840 BLE Core Module for LoRaWAN with LoRa SX1262 | RAK4631 / RAK4631-R / RAK4631-C EU868 / RAK4631 Arduino
delivered item has RAK4630 written on it NOT RAK4631
SKU: 115000
Solar panel: 5W 12V https://amzn.eu/d/00T2ABM3
[Mark 1 fail: The following items did not work - no charging of battery took place —
Voltage limiter: RAK Green Power Module SKU: 110049 ESP32 Arduino Green Power Module Texas Instruments TPS55165-Q1
With a jack and socket connector (solar panel to voltage limiter): https://amzn.eu/d/04fG5nUG
Yes, I did get a polarity wrong initially, ha ha, but then I swapped out the Green Power Module and also used a different RAK board in case I bust them, but I got no evidence of any charging even then. Even measuring the voltages was no use - there was no location I got any 5 V reading, perhaps everything was covered in resin that I was touching with the multimeter. If anyone can get this to work… would be happy to hear where I went wrong. So these parts are not used in the Mark 2 node. This comment reports no problem with the Green Power Module RAK solar node automatic restart, after brownout, upon eventual solar re-charge? - #20 by jdhgmann04]
Waveshare solar power manager: Solar Power Management Module, for 6V~24V Solar Panel - Opencircuit part number 12073 shown below:
I left the battery holder of the Waveshare solar power manager empty (there were no ill effects apparently of putting in a battery as well as the main one listed below, but it did not seem right nor necessary).
USB A to usb C cable (short): https://amzn.eu/d/0jbfYRWA or the one mentioned below for a USB connection to outside of box.
or better a right angle connector USB A to C https://amzn.eu/d/06mb5IRA or similar
Antenna: Eightwood https://amzn.eu/d/0edHQQxz
Antenna IPX to SMA connector: https://amzn.eu/d/00GRgcYn
Battery: 10000 mAh LiPo EREMIT 3.7V 10.000mAh High Capacity LiPo
Box: Distrelec Art. Nr. 303-75-350 RND 455-01406 | RND Plastic Enclosure with Clear Lid Universal 180x120x60mm Light Grey Polycarbonate IP66 / IP68 / IK07 | Distrelec Germany
4 screws (Spax 3 x 12 Z1). 2 to fix boards to the base of the box, with an M4 nut and washers merely as spacers because screws are too long. (The holes in the base of the box are wide and not deep - and I was not able to find any short, fat, ideal screws to fasten things into those holes.) 2 such screws to provide holders for cable ties (see the build photo) that hold battery down.
Cable ties, two, 150 mm long x 3.6 mm
Construction steps:
Flash the Rak board using the on-line meshtastic flasher.
Cut off the crocodile clips of the solar panel and expose the ends of the wires. Tin the ends with solder: keep them thin. Connect to wire terminals of the Waveshare board. Plug in the battery (the polarity has to be correct, which it was already. Else make an adaptor to swap polarities using JST connectors https://amzn.eu/d/0dvFShcy ). Jam the collar panel into the transparent lid. Put the components into the box, with the antenna diagonal and ever so slightly slightly bent.
Screw one screw into each board (you may need an M4 bolt and washers as a spacer if the screw is too long).
Fix two screws next to the battery on either side. Double up two cable ties to make one long cable tie and span the two screws using the cable tie to hold the battery down.
Place thick foam above battery so that the solar panel is pressed upwards against the lid when the lid is screwed down. Instead of screws you can just pad out the box so that nothing rattles nor moves - but I wanted to see the lights on the boards to be able to know what the boards are doing and because it looks nice, and padding will block the view.
Improvements for the future: A vent (like this https://www.distrelec.de/pressure-compensating-plug-m12-12mm-ip68-ip69-polyamide-black-wiska-ltd-evps-12-black/p/30158346 Vent Plug EVPS 12 Black M12 12mm 1Nm PA6 Black, Distrelec Art. Nr. 301-58-346) might be a good idea: update - the delivered vents do not come with the required plastic M12 bolt to fix them so I did not manage to install one, but will sometime as it does get a bit steamy in the box in the sun.
The waveshare board allows for a USB micro connection to charge the battery and run the node, and the box would benefit from having a link to that USB connection. I did that using a bulkhead feed-through https://amzn.eu/d/02HzoTlZ . To get this to work you need to use this USB connector https://amzn.eu/d/0bbACHC3 otherwise there is not enough room at the connections to the Waveshare board to have both USB C out and USB micro in. The steps for this are to make the hole in a location that does not cause a problem for the other components. One has to be very careful with the choice as the bulkhead connector is very bulky on the inside of the box and can easily block the battery. There are also raised parts for screws in the base and the bulkhead on the inside will not sit properly if it is located too near one of those raised parts (any yes, mine worked purely by fluke).
Bad points: the box has lips at two ends for mounting, as this might be considered a bit of an annoyance as the box is then less-boxy. The RAK node has in this build no sensors etc.
With this node I got a report of traceroute from a node about 29 km away…and it “beat” the main node on the left in this location:
because it was “first” is the traceroute !
The last step in the traceroute (Hanbury to MRbx) is shown on the map below and is about 25 km
so I think the plastic box and solar panel do not really stop reception too much - or maybe the alignment of the box was a fluke and a different position would not have worked…
Fits in a small bag too 
basically I have this bag in the house and link to it with the phone to get access to nodes that might be further away that bluetooth can manage (anything further than 15 m in my tests…).
