How I Built An Awesome Lightweight Off Grid Helium Miner

How small can you build an off grid min­er? Can every­thing fit in one back­pack? How light can that pack be? Final­ly, why would you want a tiny off grid miner?

And yeah, those are Pup­pies Make Me Hap­py sunglasses. 

Hey, before we go any fur­ther, please know that I’m NOT an elec­tri­cian, this is NOT pro­fes­sion­al advice, I’m just a dude who enjoys tin­ker­ing and build­ing things. Some of these com­po­nents, includ­ing but not lim­it­ed to the bat­tery & charg­er, can cause seri­ous haz­ard if not cor­rect­ly installed. Please find a local pro­fes­sion­al to help you exe­cute a safe deployment. 

I’ll start with the last ques­tion. Why would you want a tiny off grid min­er? The short answer is “weight”. If, like me, you are super stoked on the idea of hik­ing in an off grid min­er to a place deep in the wilds, you will even­tu­al­ly get over the idea of car­ry­ing in heavy equip­ment. I did that on my first off-grid, car­ry­ing in awk­ward­ly loaded 60+ lb rucks over 6 miles of rugged ter­rain with 3k’ of gain. 

It was the hard­est thing I’ve done since run­ning a hun­dred miles back in 2015. Fun once, and rad to share with a friend (we EACH had huge, awk­ward loads to car­ry), but not some­thing I was des­per­ate to repeat.

Still, being gen­er­al­ly unafraid of phys­i­cal work, I did the same thing a few more times, just to be sure it was­n’t just a one-time suck­fest. One off-grid took 6 (SIX!) trips in to install.

By that time, I fig­ured out that while I real­ly like hik­ing heavy shit long dis­tances out in the moun­tains, I’d prob­a­bly enjoy hik­ing in a light ruck even more. So I set about build­ing one. I also want­ed to re-mea­sure my ini­tial pow­er draws because I was see­ing off grid setups that seemed small­er with a high­er load..

After a con­ver­sa­tion with @BFGNeil on Dis­cord about using a Pi Zero and a RAK 2245 hat to put togeth­er just the pack­et for­warder (from a DIY Alpha code I received way back when they were still avail­able), I decid­ed to try it out. The enor­mous advan­tage of hav­ing just a pack­et for­warder (and not the full fat min­er) is the low­er data plan size I can use for the cell backhaul. 

I cannnot over­state this advan­tage. Please do NOT think you’ll be able to use a small data plan (100MB or less) on your pro­duc­tion Heli­um com­pat­i­ble Hotspot. You’ll need 50 GB MINIMUM, and will be much safer with 100 GB. I got lucky to find Heli­um right as they launched (and then quick­ly closed) the DIY pro­gram. This guide gives you an idea of what a Light Hotspot will be like.

One last note before we dig in. Off grids are hard, and com­pli­cat­ed, and some­times com­plex. If you just want to buy an off grid set­up, I’d start with IoT Off Grid. If, how­ev­er, you LOVE build­ing your own stuff, keep reading!

Let’s start with a gear list. 

PLEASE NOTE: This is MY gear list. It will prob­a­bly not fit exact­ly what YOU are try­ing to do. My goal is to have a tiny, light­weight, right-on-the-edge of pow­er require­ments for a Light hotspot in a high sun area. Make SURE you mea­sure your pow­er draws before just blind­ly order­ing what I used and think­ing it’ll mag­i­cal­ly work for your area. Your chal­lenges will be mak­ing sure you have enough pow­er and mak­ing sure you have enough data. 

The great news is that pack­et for­warders are what “light hotspots” will be, so it’s like­ly that you’ll be able to do this same thing and in a clean­er look­ing pack­age by mid-2022.

The sec­ond advan­tage of a Light Hotspot is the low­er pow­er con­sump­tion. Com­pared to a reg­u­lar min­er, with a pack­et-for­warder-only set­up you can shave off enough watts to real­ly drop both bat­tery size and solar pan­el size.

Here’s the pow­er it’s pulling. Note the size of that “hotspot”. It’s MUCH small­er than cur­rent pro­duc­tion hotspot, and pulls about ½ of the power.

https://vimeo.com/572397052

Remem­ber, volts x amps = watts, so this is right around 1.5 watts. It jumps around a bit, but in any event, that ain’t much. 

Add in a cell modem and the solar charge con­troller with the pack­et for­warder on a Pi Zero and you’re look­ing at about 3.4 watts total. For com­par­i­son, a RAK V2 by itself pulls around 2.3 watts.

Want more data on pow­er draws? Here ya go!

Of course, it also depends on the win­ter sun hours in your area. If, like me, you live in Amer­i­ca’s Finest City (San Diego), you have more win­ter sun hours than just about any­one in the US. That means you can use a much small­er solar pan­el (30 watts is what I chose) as well as a small­er bat­tery (20 Ah in my case.)

I put those togeth­er in an enclo­sure with the pack­et for­warder, a small­er cell back­haul (IBR200 instead of the 650C I’ve used before, many off grid­ders are now using a Spitz), the same charge con­troller I’ve used, and had a tidy lit­tle package.

Still, you’re left with mount­ing the thing, which can be a real bear. The solu­tion I came up with was inspired by some­thing I saw over at MP Anten­na, plus the fact that I love to hand bend metal. 

I start­ed out with a sheet of 12″ x 48″ .0125 5052 alu­minum. 5052 is a good mix of tough­ness and rigid­i­ty. 6061 will crack when you bend it, and 3003 will flex too eas­i­ly. I marked out the holes for cut­ting and the lines for bending.

I want­ed to be able to mount this brack­et any­where, eas­i­ly. One of the chal­lenges of an off grid set­up is actu­al­ly mount­ing the thing. Though you can’t see ’em in the above pic, the lat­est ver­sion has slots for worm dri­ve (hose) clamps as well as the screw/bolt hole mounts you see here. This will eas­i­ly mount to a round object, like a pipe or a pole or a tree. It’ll mount to a flat sur­face as well, like a rock wall or the side of a building.

Next up is drilling & cut­ting ’em out. Alu­minum is pret­ty easy to work with, which makes this a nice project.

Next up was cut­ting the “win­dow”, which allows you to reach in with a drill and mount on the back holes before putting the solar pan­el on. Here’s the plate drilled and cut, ready for bending.

When I go into pro­duc­tion (that’s a joke, by the way) I’ll use a press brake and water jet, but for pro­to­typ­ing you can’t beat a bar clamp (as long as you don’t mind a lit­tle phys­i­cal work). You put the plate in the bar clamp, make sure your bend line is straight, tight­en every­thing up, and start ham­mer­ing. Hand bend­ing takes patience; you don’t see a lot of progress at first, but over time you’ll end up with a beau­ti­ful­ly bent line.

https://vimeo.com/573430910

As you can see, I set up a lit­tle card­board angle mea­sure­ment device which gives me an angle of 148, or a 32 degree bend. 32 is our lat­i­tude, and gives your solar pan­el the most sun rays dur­ing the short­est days of the year. Here’s what it looks like with the first bend finished.

From there you just slide the plate up and ham­mer out a 90 degree angle. I’ll usu­al­ly go back and forth a few times with the bends. On a press brake you don’t need to, but when hand bend­ing I always find a lit­tle extra love makes for a clean­er job.

It’s not uncom­mon to have “extra” bends in there, which you’ll need to flat­ten out on an anvil. In this case the “roof” had a slight arc to it. I leap at any chance to use my Nim­ba Titan, here she is ready to assist in the flat­ten­ing process. Man, the right tools make the job easier!

All that ham­mer­ing attract­ed my wife’s atten­tion. She knew the best fuel for any endurance event is the cake from Paleo Treats, so she brought some out. Damn, that Key Lime is good!

https://vimeo.com/573431945

Fueled with cake and ready for the next step, I assem­bled the box, the pan­el, and the antenna. 

This next part may be con­fus­ing, as I’m using pic­tures from a few dif­fer­ent builds here. The parts you see in this build on the inside of the enclo­sure are the RUT240 cell modem (NOT the IBR200), a Ren­ogy Wan­der­er 10, and a Bioen­no Pow­er 20 Ah LiPoFe4 bat­tery. The hotspot itself is a Pi Zero cou­pled to a 2287 con­cen­tra­tor and Pi hat from Par­ley Labs. 

Here’s just the RUT240 and the DIY Hotspot.

I print­ed up lit­tle red PETG brack­ets for the RUT240 and the Pi Zero on my Prusa 3D print­er. At about $800 for a kit, they’re a very use­ful thing to have if you get into this off-grid world.

If you don’t have (or want) a 3D print­er, go to the Prusa World map page and look for folks near you who are will­ing to print them up for you. That’s how I did my first 3D prints. Here’s the Pi Zero nes­tled into its brack­et. Brack­ets make it very easy to attach com­po­nents to the “perf board” that comes with most enclosures.

Wait, you want every­thing labeled for ya? No prob:

Here it is mount­ed on the near­est avail­able space (my work­bench) as a test run. Please note that you’re not lim­it­ed to mount­ing on workbenches. 😉

The box still needs vent holes cut and vents mount­ed along with the holes & glands for anten­na cables, but this gives you an idea of how the thing works. It is WAY eas­i­er than any oth­er off grid mount I’ve built. Here’s a quick video of it with the HNTen­na and a cell anten­na mount­ed, though no cables run yet.

https://vimeo.com/573292248

The next step is break­ing it all down and see­ing if I can fit it in my back­pack. One of the real beau­ties of this set­up is how small it is. Most back­packs on the mar­ket are way too small to fit a large enclo­sure. This back­pack is built for elk hunters to car­ry out their meat, but I fig­ured Stone Glac­i­er would­n’t mind if I repur­posed their EVO 3300 as a telecom­mu­ni­ca­tions pack. To be clear, this is not (by far) the cheap­est pack you can buy to do this job. I just like nice things.

From left to right you’ve got the pack, the solar pan­el, below the pan­el is the HNTen­na, then the enclo­sure with a GK tool roll on it, and final­ly, the bracket.

Now, that brack­et has some sharp edges, so if you’re going to strap it on a pack you’ll want to cush­ion those. I had some left­over foam lay­ing around the shop, so I taped it on with painters tape (comes up off eas­i­ly) and set up the pack.

You can’t see it in that pic, but I’ve also padded the solar pan­el, which is against my back in the pack. While the pan­els don’t scratch super eas­i­ly, they’re not the tough­est thing out there, and any scratch can decrease the effi­cien­cy. That’s some­thing you want to avoid when you’ve got such a small pan­el. Here’s the pack with every­thing in it, all ready to go.

I’m guess­ing the whole thing weighs less than 35 lbs. If you’ve ever got­ten into pack weight and how it can effect your abil­i­ty to per­form under pres­sure, you know that this is right at the lim­it of what saps courage over time. I’m not expect­ing to engage in any fire­fights while mount­ing this thing, so I feel pret­ty safe, even if I’m slight­ly over S.L.A Mar­shal­l’s rec­om­mend­ed weight.

After load­ing the pack up I decid­ed to re-wrap the brack­et with a clean­er look­ing foam set­up using pipe insu­la­tion. Here’s what that looks like, just for reference.

The gear is pret­ty straight­for­ward (aside from the brack­et). This is a slight­ly dif­fer­ent set­up than the one I’ve shown you. Try to iden­ti­fy the com­po­nents on your own, hit the com­ments if you need help.

IBR200 cell modem, Ren­ogy Wan­der­er charge con­troller, 12–5v buck con­vert­er, and then what­ev­er your hotspot is. Here’s the inte­ri­or lay­out with almost noth­ing hooked up. The two pink/orange cables go out to the cell modem anten­nas. You can see the vent up at the top right. There’s also one at the bot­tom left. Because the PiZe­ro does­n’t have a native Eth­er­net con­nec­tion I picked up a con­vert­er for it. Every­thing else is pret­ty straightforward.

If you’re look­ing to do this same thing, keep in mind that this enclo­sure may NOT fit your hotspot, at least as I cur­rent­ly have it laid out. RAK V2s will be fine, but oth­er hotspots may need to be mount­ed on the door, or just require a reshuffling.

Ok, that wraps up most of the details on this project. If you’d like help get­ting your Heli­um Hotspot off grid, con­sid­er hir­ing me to walk you through the best ways to both build and place your hotspot. Rock on!