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[on:]

Hello,

i have an Arduino Uno R3 and EthernetShield in my pool automation project.

The winter is slowly beginning over here in germany and i wonder if the boards can withstand freezing temperatures?

(The boards are not directly exposed outside, they are in a shed in the garden, but it's freezing there too.)

[Reply #1 on:]

"Withstand" = ?
Operate?
Hibernate?

[Reply #2 on:]

Hello,
you are right, it really gets cold in Germany, I live here, too.

I think the question is whether your Arduino should operate at these temperatures or just not crash without operating (hibernate).
(this is storage temperature and working temperature)

A similar question has been posted here.
And here.

The datasheet of the processor (ATmega328) sais

Temperature Range:
 -40°C to 85°C

However, whether, and if yes, in how far this can transferred to the Arduino board, is not very clear for me.

Hope this helped

[Reply #3 on:]

Sorry i did'nt express myself clearly.
What is meant is: Can an Arduino operate at these temperatures?

[Reply #4 on:]

I said the MCU operates in the range of "-40°C to 85°C" according to its datasheet linked above.
Whether this goes for the Arduino board is not completely clear for me, but I guess yes.
I recommend using insulated boxes or so if it is really necessary...

[Reply #5 on:]

Can an Arduino operate at these temperatures?

It is not so much the temperature that will get you but the condensation you get as the temperature goes around freezing. It is this moisture that causes malfunctions. Those temperature claims are made in "non condensing" conditions something that rarely happens in real life.

It is not just the processor but the crystal that will suffer at low temperatures. If it is running then the heat it generates will help keep it running at temperatures it would not start at.

[Reply #6 on:]

I forgot to mention that. Condensation is a really important factor as Grumpy_Mike says. So you could put everything in a plastic box that is waterproof.

[Reply #7 on:]

Desiccant packs can also help.

[Reply #8 on:]

I forgot to mention that. Condensation is a really important factor as Grumpy_Mike says. So you could put everything in a plastic box that is waterproof.

That's going to pretty much guarantee condensation!

As air cools the amount of moisture it can hold in solution (as vapour) decreases markedly - this then condenses as droplets.
The most straightforward way to prevent condensation is to ventilate and insulate.  Ventilate to allow moist air to be replaced
by colder dry air.  Insulate to stop the rapid temperature drop as night falls - that is when condensation is most likely as heat radiates
away from objects and they become cooler than the air (not such a problem inside a shed though?)

Alternatively if you place in a sealed container you need to seal it at cold temperatures, or fill with dry nitrogen, to prevent
moisture getting in at all - and have an enclosure that can withstand the high pressure differences as temperature changes (not
cheap).

Most electronics generates a little heat which helps to prevent condensation on the circuit board - nearby metal objects are
more likely to get the condensation, so make sure the board isn't underneath metal objects than might drip - plastic or wooden enclosure with ventilation grill perhaps?

[Reply #9 on:]

Hello, I'm new to this forum, but I have been an electrician for quite a few years here in Canada. Any fire alarm annunciator that is located outside and exposed to our lovely Canadian winters needs two things... 1. a rain tight box, not a waterproof box(there is a difference) and 2. a small heating element. I have personally seen what happens to electronics left out in the weather without a heating element, the condensation kills them.

Long story short, I highly recommend finding just a small heating element to mount in your project box. The ones that I have installed are usually no bigger than 3-4 inches long and about 1/2-1 inch thick.

[Reply #10 on:]

The chip itself is likely to work at that kind of temperature. The weakest link will be the crystal oscillator, if you have one; or internal r/c oscillator's accuracy, if you don't.

If you really want to find it out, try it this winter or put your chip in a freezer.

[Reply #11 on:]

Hey,

i think i will put it in a plastic box.

The chip on the Ethernet-Shield gets pretty warm.
That should work as heating element, shouldn't it?

[Reply #12 on:]

It should.

You need to undo it in the summer.

[Reply #13 on:]

Easy enough to hook up a tmp36 or similar sensor to figure out whether the heating element needs to be on or not. Then have the arduino drive a relay once the temperatures are too low. If the power requirements are low on the board, you can conformal coat it as added protection. Any clear coat will do. Or do the GE thing and drown the board inside an enclosure under 1cm of silicone /RTV.

[Reply #14 on:]

If you can use a sealed plastic box, that is what I would do. Seal it up as tightly as possible and toss a few desiccant packs in there.
Really cheap (but very effective) desiccant can be made by baking epsom salts at 500f for half an hour or so. Non-toxic, very effective, reusable.