Making a portable Meshtastic node
I am continuing my journey with Meshtastic, and since my last post I made some progress, yet mostly in hardware. I still did not connect to anyone over LoRa*, but I had some interesting communications over MQTT bridges. And I made a portable node, and I am in the process of making and testing a solar-powered remote node.
* scratch that, just before posting this blog post I finally made contact over LoRa at 433MHz!
This is going to be a short post showcasing how I built my portable node and what are my future plans. Maybe it will be source of inspiration for someone.
The Parts
For the Meshtastic node, I am using a LILYGO ESP32 LoRa32 V2.1_1.6. It comes with a JST-PH socket to connect to a 3.7V Li-ion battery pack, and this is the powering solution I am using for this build.
Note that your device might have different power requirements, check that before following what I did.
The parts list is very short and simple:
- A plastic case
- An 18650 battery holder, connected in parallel or not connected from the factory, more on that later.
- A short SMA extender
- USB-micro charging cable
- cables and short pieces of wire, I used leftover resistor legs
You will also need the usual assortment of tools, a drill, a soldering iron, a heat gun, a glue gun and wire gun strippers.
The battery pack
When it comes to the battery holder, you can use any size that fits your needs, a single 18650, two, three, or more. What is very important is to find one that connects all batteries in parallel, or allows to freely wire it. More often than not, 18650 battery holders are wired in series, and this is not what we want. What we want is to provide the voltage of a single 18650 cell (~3.7V), and the capacity of multiple cells. To achieve that we need to connect every cell in parallel. Meaning that the positive side of every cell is connected to one wire that goes to the positive connector of the LILYGO. The same happens on the negative side, all negative cell connectors are connected with a single wire and go to the negative connector of the radio. In result, we will have a battery that works as if it was a single cell with a large capacity.
I bought a battery holder that had no connections between individual cells, so I soldered them:
Battery holder underside with no connections
Connectors on one side connected
Cable going from one side, it will connect to the LILYGO, the same will be done on the other side
The cables coming from the battery pack, I soldered them to the JST-PH connector that came with the LILYGO. Cells can be placed either way in my battery pack, so for the time being, the polarization doesn’t matter, it will matter when inserting the cells into the holder.
The antenna and charging
As for the antenna, I got this SMA extender to allow the antenna to be outside the case. I drilled a hole in the case with an 8mm drill (a 7mm would probably fit better but I did not have one), and the male end of the extender through it, secured it with the provided nut.
Finally I drilled another hole with a 10mm drill, and put an IKEA micro USB cable through it to allow charging the LoRa radio without opening the case.
Now came the big part.
The assembled Meshtastic node
Assembly
The assembly was simple, I connected the antenna, then the battery pack, paying special attention to the polarization of the cells. All have to go in in the same direction. And the cells need to be placed in the correct orientation, with the positive terminal connected to the positive terminal in the device’s socket.
Once I was sure everything was working fine, I hot glued the battery pack to the case. I put the charging cable through the larger hole, tidied it with some cable straps, and hot glued the whole to keep it in place, leaving a short length dangling for easier charging.
Finally I put a piece of foam inside the case to make sure things do not rattle around when carrying, and screw in the lid.
And that’s basically it! Short, fun project that resulted in a Meshtastic node that you can safely carry around, and when using three or so 18650s, will work for a few days without charging. My case is relatively weatherproof, and safe to carry in a backpack.
My node living free in the wilderness
Future improvements?
One downside of this build is that there is no way to see the screen, but then again, I use the Android app to interact with the radio and do all the configuration. What I would actually add to the node in the future would be an on/off switch to conserve battery, and maybe a cable holder to stop it from dangling freely.
Continuing my Meshtastic journey
I am planning to take this node on a trip with me to some cities and try to make contacts with the locals.
Apart from that, I am right now building and testing a solar-powered node that will eventually be placed on my piece of land. A blog post on it should appear in the next few weeks.
Many thanks to people of Mastodon, and Meshtastic, and Meshtastic Polska Facebook groups for feedback and inspiration.
If you enjoyed this post, please consider helping me make new projects by supporting me on the following crowdfunding sites:
