Hi. I am working on a project that is meant to be able to last for a long time (5 years at least). The Arduino is inexpensive and the Arduino IDE makes it extremely easy to program the on-board microcontroller, which makes it the very top choice among hobbyists. But I think everyone would agree that the Arduino is not exactly an industrial grade product, which makes me wonder if it is safe to assume that the Arduino will just keep on operating by itself for such a long duration of time, given that I provide nice steady power supply of course. And also, is there something I can do to enhance the reliability? Thanks!
Edit: To be specific, I am building a data-logger for a solar array. Components include 3 arduinods, 12 sensors, 2 xBee, an LCD with resistive network buttons, and an ethernet shield with SD card. Currently everything is setup on breadboards and apparently working nicely so far, and I am going to have my custom PCB to integrate all the sensors. I won't have access to the data-logger after I'm done because that solar array is going to be installed in a village in Africa. While it is really not that big of a deal even if my logger fail completely after some time, but I do want to know how long can I expect it to last, and if possible, maximize its lifetime.
I wouldn't expect wires plugged into the socket strips of the Arduino to hold up very well, but aside from that it's pretty much standard components assembled with standard manufacturing methods (and relatively conservative parameters on things like power and temperature), so I wouldn't expect it to be any worse than any other random bit of electronics...
yes, but sort of depends on the enviroment, sitting on a desk for 5 years is a bit different than sitting in a box, outdoors, on a 20 foot pole for 5 years
westfw:
I wouldn't expect wires plugged into the socket strips of the Arduino to hold up very well,
I made the PCB such that it is just like another shield that can be stack on top of the Arduino board with pin headers. So is it reliable enough or if there's more I can do (like taking the ATMega/resonator/etc out and make one single board)?
sitting in a box, outdoors, on a 20 foot pole for 5 years
well... one of the arduinos is actually going to be placed inside a junction box attached on a supporting stand of one of the panels. I'm sure the box is waterproof though.
Truthfully, there are maybe 100 items that you would need to look into to get the highest reliability. Such as:
What temperature range/humidity range will it have to operate at? This will determine the components you need to choose.
What are the power supply requirements? Are batteries involved? Batteries turn this into a more difficult solution.
There are things that you can do to improve reliability:
One board. The fewer connections, the more reliable.
Double connections going off the board.
Good connectors.
Quality parts.
Test it before you send it out. Test it every which way. Low voltage/High voltage. Low Temp/High Temp. Vibration.
Solder the Mega328 and all I/O wires directly to the board, get some mil-spec capacitors and you're good to go.
Shield pins are probably long enough to solder directly to the base PCB. Snip off the shield pins where your I/O wires are connected to the base PCB. Solder what's left into place.
I won't have access to the data-logger after I'm done because that solar array is going to be installed in a village in Africa.
Most universities with engineering schools have professors familiar with designs for adverse conditions. I would approach the college through their outreach department and request a consultation. You need to approach the concern from a best-practice and system (weak link) perspective.
There are chemical products that can make connectors less likely to fail due to environment, but nothing short of a sealed environmental container can eliminate condensing humidity - sure death threat.
As you are making your own pcb, include the atmel chip, crystal (if needed) and voltage regulator (if needed) on the same board, to avoid connections between 2 boards.
If you do need to use any connectors, use good quality ones with gold contacts.
Spray the board with PCB lacquer to reduce problems with condensation.
Mount it in an enclosure that is weather and insect proof.
Test it at the highest and lowest temperatures that you expect it to be subjected to.
Avoid using more power than necessary - components are less reliable when they get hot.
Didn't say where in Africa, but some parts are very dry and dusty, with extremes of temperature (like in the Sahara). Others are very hot and humid, like Durban which is sub-tropical and it's even worse closer to the equator.
How does weather / insect proofing go with heat dissipation? Could there be a problem with a hermetically sealed (or potted) box which does a great job of keeping dust, moisture and kreepy-krawlies out, but which keeps too much heat in?
JimboZA:
How does weather / insect proofing go with heat dissipation? Could there be a problem with a hermetically sealed (or potted) box which does a great job of keeping dust, moisture and kreepy-krawlies out, but which keeps too much heat in?
That's why I included item 6 in my list of suggestions.
JimboZA:
How does weather / insect proofing go with heat dissipation? Could there be a problem with a hermetically sealed (or potted) box which does a great job of keeping dust, moisture and kreepy-krawlies out, but which keeps too much heat in?
That's why I included item 6 in my list of suggestions.
High power devices should be heatsinked to the outside box before potting (use a metal box). The whole thing should be shaded from the sun (underneath the solar panel).
That's why I included item 6 in my list of suggestions.
Yep, I got that, but I was also thinking of ambient heat, heating an unventilated box like an oven.... you know what it's like in a car that's been parked in the sun (ok, maybe not so bad with high latitude angled sun, but tropical).
Might be an idea to consider some kind of thermal insulation...
Take a look at the Arduino Pro made by Sparkfun, or the headerless version of the Leonardo board. They have surface-mount chips, so no IC socket to corrode and fail. They come without shield headers, so you can solder your shield directly to the Ardunio PCB - made easier by the low height of the SMD components.
The type of enclosure and the environment it has to withstand will greatly determine the lifetime of the electronics it contains. If you can mount the electronics under some kind of shelter then that will help considerably. Do you have batteries or other heat-sensitive components requiring ventilation? If air can get out, moisture can get in. If the enclosure is plastic and exposed to the elements, consider a sun-shade or UV-resistant paint. A lot of plastics age badly in strong sunlight, although some last longer than others.
While I have never been in an African village, I spent years in the chemical industry and worked with electronics in the army before that. I am pessimistic that your installation would operate for very long. Systems for use like this are normally ruggedized based on long & painful experience.
Your system will 'glitch' for a host of reasons even if not damaged. Who brings it back on line? Are you familiar with watchdog timers and other auto-resetting techniques? Solving Power quality problems from dying batteries to lightning strokes can be difficult or expensive. We could go on for pages.
Your design may well be suitable for occasional portable check out of the solar array, but doubtful as a permanent installation.
Arduino "as-is" is of course not suitable for such remote installation outside. The reliability must be "built-in" when targeting such rugged designs..
An example: Wierd military computer boards - YouTube
If the box is mounted in the shade (either from the solar panels or some other source of shade you will not have the heating problems that you would have in an automobile parked in the sun. The only heat you will have to deal with is ambient. Make a sealed box with an aluminum back and bend a set of fins for the inside and outside. That way the inside fins can heat sink any heat above ambient to the outside fins where the heat can move into the air. For sealant use a urethane roof sealant rather than silicone sealant. It sticks better and lasts longer. (it even sticks to you better...) Kind of like black mastic but in a semi viscous form.
How close is this to the ocean? A sea breeze can corrode things miles away. I live in South Texas and 30 miles from the ocean we have to deal with corrosion problems.
Looks like my designs from the early 90's. Lot of it obsoleted now with smaller, denser parts.
CAGE Code 49956 was Raytheon in MA.
Gloss finish is due to conformal coat.
Am surprised these were available for posting to the internet.
Wonder how he got his hands on them.
Nice video, indeed. You may see a LOT of reliability components built-in. Fan less cooling via thick built-in copper layers, I guess. Coating. Large sized smd capacitors and resistors. It seems all the signals passed via resistors into the connector's pins. Doubled cpu's master-checker? Old sub stuff, I would say
PS: 1980's design, milVAX by DEC - Wierd military computer boards
pito:
Arduino "as-is" is of course not suitable for such remote installation outside. The reliability must be "built-in" when targeting such rugged designs..
Wow, that's impressively well made.
The high-res pictures on his web page are interesting, too, and there's even some background info from the person who designed them:
