How to enclose outdoor SBC in hot area? - Page 1
Forum section: electronics / projects

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: June 21, 2025, 02:02:07 am
content: Ok so I put together a a solar/battery powered SBC and software defined radio. The idea is to haul it to the top of a mountain behind my house and remote in to it over a long range WiFi link. The thing runs great but when I bought all the stuff I never really thought about enclosing and cooling it. I live in the desert and it will routinely get up to 115F/46C during the summer. I am running an x86 n100 based SBC with a decent cooler, I can not get the CPU to break 47C under torture tests in a 24C house. Will it survive just sticking it in a weather sealed cabinet with no ventilation?

author: radiolistener
author_rank: Super Contributor
timestamp: June 21, 2025, 02:50:24 am
content: Quote from: rwgast_lowlevellogicdesin on June 21, 2025, 02:02:07 amBased on my experience, poor ventilation will quickly lead to overheating of the SBC, even with natural convection - especially if it’s running a demanding task like processing a wideband signal. If you place it in a fully sealed enclosure, the thermal situation will become significantly worse.A good passive solution is to use a metal enclosure where the CPU, RAM, chipset, and voltage regulators are thermally coupled to the case using thermal pads. This allows the entire enclosure to act as a heatsink. However, keep in mind that a metal enclosure will severely attenuate your WiFi signal, even with plastic window, so you’ll need to use an external antenna.Also, be aware that WiFi can introduce noticeable interference in the HF (shortwave) and especially VHF bands, which may impact SDR performance depending on your use case. Especially for weak signals.I’m using a Raspberry Pi 4 enclosed in a metal case with an additional heatsink on top. With this fully passive cooling setup, the temperature remains within 45-50°C under typical load and only reaches around 60°C after 30-40 minutes of sustained full-power operation (approximately 5 W at constant 400% CPU load).

author: brucehoult
author_rank: Super Contributor
timestamp: June 21, 2025, 02:54:20 am
content: N100 has a maximum operating temperature of 105° C (221 F) so it's going to be pretty hard to hurt it!I assume there's usually a breeze on top of a mountain. Can you rig a sun shade with an air gap to the sealed box? Maybe the solar panel itself.

author: Psi
author_rank: Super Contributor
timestamp: June 21, 2025, 03:21:59 am
content: I would probably look into- Using a metal box, probably stainless.- Figure out a way to thermally connect the SBC CPU heatsink to the metal case. It doesnt have to be prefect but you want a path for the heat to flow to the case. Could be a block of metal bolted/thermal-glued to each, or a heatpipe would work well if you can figure out how to connect to the SBC heatsink.- Bury the metal box in the ground. This helps by getting it away from the hot midday sun. Underground is much more stable temp wise. I'm not sure exactly how deep to go but I would imagine just 10-20cm would help a huge amount over having a box above ground in midday sun.I reckon the above would probably work fine to keep a Raspberry pi 4/5 spec'ed SBC in a good temp range. I'm not sure how much hotter a N100 gets.You'd obviously need to do some test.Another approach could be to use a huge box. Something with a large amount of free air inside.I'm thinking the size of a banana box or 2, way bigger than you need for what's going inside.If you have enough free air inside the box it will help the fans get heat away from the hotspots, like the CPU.The size of the box will help to dissipate that heat out the sides of the box to the environment.Could be a metal box or a plastic box designed for use outdoors (thick walls and UV stable). Metal would be better but plastic would be much cheaper.You could do a test using a small cheap temperature data logger in the box you plan to use. Put that into the location you plan to use and log internal box temps for a week.That will get you an ambient temp to work with.Then you can do your own tests at home to see what temp the parts get to when in a box heated to that temp.Maybe powering up the SBC in a toaster oven set to 50C for example.Just be careful with ovens intended for cooking. The temp setting knob on the front can be very wrong at lower temps, and they have large temp swings because the heating element cycles 100% and 100% off. (So when set 50C it might swing up to 80C and down to 35C for example. Might not be that bad, but yeah, something to keep an eye on). Also the IR from the elements can scorch things. So you'll want to shield the item from the IR from the elements.

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: June 21, 2025, 03:56:22 am
content: I didn't even think about burying it! Thats acually a great idea, especially if i use the panel to shade the ground over it.I didnt know that wifi caused noise issues on the HF bands. The SDR antennas will be mounted up a 10 to 20 ft pole or maybe in a tree taller than that, and the wifi will most likely be a dish or yagi at least 10 ft from the SDR antenna and much closer to the physicall ground. It will also be a 5.8ghz link, not sure how much that matters.

author: Psi
author_rank: Super Contributor
timestamp: June 21, 2025, 03:59:30 am
content: I saw a burred PC setup that used two boxes.They burred a metal heat-radiator box with lots of fins on it, and an electronic box with in/out water cooling tubes between them.

author: Kasper
author_rank: Frequent Contributor
timestamp: June 23, 2025, 05:32:00 am
content: I'd check the max charging temperature of the batteries.

author: 5U4GB
author_rank: Super Contributor
timestamp: June 23, 2025, 07:00:33 am
content: Another option would be to pot it with finned heatsinks on anything that can get hot sticking out through the potting compound. I've worked with plenty of stuff set up that way, there shouldn't be any problems with heat trapped inside the waterproof envelope.

author: RoGeorge
author_rank: Super Contributor
timestamp: June 23, 2025, 07:23:02 am
content: Don't know much about deserts, but I guess the underground temperatures are not that harsh. I'll try do dig a deep enough hole in the ground, and put all the electronics in it, with only the antenna, and eventually the power cable left at the surface.

author: 5U4GB
author_rank: Super Contributor
timestamp: June 23, 2025, 11:00:02 am
content: One issue with burying it is that most deserts do at some point get rain, for example when I'm out in the middle of one trying to get desert photos, so digging a water collecting pit may not be the best option for electronics. Depending on how much work you want to put into constructing something you could take the knowledge of desert-dwelling cultures and do it the way they do. For example in Africa a structure like arondavelkeeps remarkably cool when it's crazy hot outside. Another option for natural cooling is a windcatcher.

author: brucehoult
author_rank: Super Contributor
timestamp: June 23, 2025, 11:11:03 am
content: Quote from: RoGeorge on June 23, 2025, 07:23:02 amThe thing about dirt being a good insulator is that it will also make it hard for heat generated inside your box to get out.

author: tszaboo
author_rank: Super Contributor
timestamp: June 23, 2025, 11:22:48 am
content: Is it a rocky desert or sandy desert?My first go-to would be a Rittal/Schneider Electric (or other brand) IP66 rated electrical cabinet. If your N100 doesn't use too much power, than having no external ventilation might even be acceptable. I certainly wouldn't bury it. Something like this is used in all kinds of industrial application, and you will find these boxes on Cell towers, which is almost what you are trying to do. CPUs are often rated to work at 90C constantly.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: June 23, 2025, 08:58:20 pm
content: I tend to agree with bruceholt here. When buried it would be more difficult for it to get rid of it's own heat, unless it's below ground water level. so at the least this would need some thorough testing. But if you have a solar panel, you also have shade. Also, if you make sure your whole board is rated for an "industrial temperature range", then it should work in an environment up to 85c. "Military temperature range" is up to 125c, and for automotive stuff it's up to 105c. There is plenty of electronics that is rated for pretty high temperatures.

author: Kasper
author_rank: Frequent Contributor
timestamp: June 23, 2025, 09:48:27 pm
content: Quote from: Doctorandus_P on June 23, 2025, 08:58:20 pmWhat do they use for batteries?

author: Geoff-AU
author_rank: Frequent Contributor
timestamp: June 24, 2025, 04:04:05 am
content: Quote from: rwgast_lowlevellogicdesin on June 21, 2025, 02:02:07 amIn the short term, a sealed cabinet may have heat flow issues to the outside. Making sure the cabinet is metal will help, and absolutely not located in the sun (1000W/m^2 heating on the enclosure). Thankfully you're also dragging a shade panel up the hill, put the SBC below that.In the long term, a sealed cabinet tends to suck in moisture. Nothing is ever sealed, pressure changes will always develop due to thermal differences, and the seals are never perfect. Usually what happens is the enclosure gets hot in the sun and pushes air out past the seals, then it rains and the enclosure cools down and sucks in humid air (and water, if it can) through the seals. So the inside gets wetter and wetter over time, the moisture has a hard time getting back out.I drill 2 x 3mm holes in the bottom of all my sealed enclosures to avoid this issue.But for your case, a ventilated enclosure under your solar panel will keep most of the dust out, all of the rain out, and keep the SBC cool enough.

author: brucehoult
author_rank: Super Contributor
timestamp: June 24, 2025, 05:12:46 am
content: Quote from: Geoff-AU on June 24, 2025, 04:04:05 amDepending on where you live, the problem with holes is insects.3mm should keep out paper wasps and bees, which is good because the last thing you need is comb inside your electronics box. 5mm is too big. But that still leaves ants.

author: Psi
author_rank: Super Contributor
timestamp: June 24, 2025, 10:56:24 am
content: Yeah, you probably need to make a design decision on how long it should last in the ground with zero maintainance.Are you ok digging it up after a year and servicing it? or does it need to last 5/10 years.A lot of the time burry systems are designed for longevity with zero serving and that adds a lot of complexity.But if you don't need that it will be easier to design.Sometimes you just have to try it and see how long you getBut i would do some thermal tests to confirm its not going to get too hot.Sometimes it's worth adding a 2nd low power PC to the system which can stream the HDMI output of the primacy PC and simulate HID keyboard/mouse (and power in on/off). Just so you can do a full remote OS reinstall of the primary PC if you need to.Some motherboards have this sort of remote management built in.But that might be overkill for your application.Stick a USB webcam and some switchable LEDs inside the box, just for lols.You can keep an eye out for any changes that might indicate bugs/water entry etc..Temp/humidity sensors might be useful too. Im sure you can get a small BLE temp/humidity sensor for cheap that runs from a CR2032 and lasts a year or two.

author: brucehoult
author_rank: Super Contributor
timestamp: June 24, 2025, 12:17:37 pm
content: Quote from: Psi on June 24, 2025, 10:56:24 amhttps://www.jeffgeerling.com/blog/2024/sipeed-nanokvm-risc-v-stick-onNote: this review was 9 months ago, with a pre-production version.

author: robert.rozee
author_rank: Frequent Contributor
timestamp: June 24, 2025, 01:10:29 pm
content: Quote from: brucehoult on June 24, 2025, 05:12:46 amsee Gore-TEX vents, such as this:https://nz.rs-online.com/web/p/enclosure-ventilation/2821500or for a more 'crude' solution drill a hole as others have suggested and place a piece of felt over it inside the enclosure with a metal retaining clip holding the felt in place.years ago i saw a fully-sealed enclosure that over a period of time managed to suck water up through the centre insulation of a coax antenna cable. it finally failed (after many months) when the water inside reached the level of the PCB! solution: we added a vent (that one of the bean counters had dropped to save money) back into the design.cheers,rob :-)

author: brucehoult
author_rank: Super Contributor
timestamp: June 24, 2025, 01:32:51 pm
content: Quote from: robert.rozee on June 24, 2025, 01:10:29 pm27 bucks, dayum!Find someone who has a roll of these .. $5.90 eachhttps://nz.rs-online.com/web/p/enclosure-ventilation/0425410

author: 5U4GB
author_rank: Super Contributor
timestamp: June 25, 2025, 08:37:45 am
content: Quote from: brucehoult on June 24, 2025, 12:17:37 pmThere are lots of these, coming from the original PiKVM project (e.g. BliKVM), you can pick and choose your preferred form factor, features, and price levels.

author: 5U4GB
author_rank: Super Contributor
timestamp: June 25, 2025, 08:43:06 am
content: Quote from: brucehoult on June 24, 2025, 01:32:51 pmAmphenol also make them and they're a few dollars each because it doesn't say Gore on them. They also (AFAIK) don't engage in the unethical business practices that Gore does.