Safe Running Temperature.

[PotatoHandle]

Just a quick and dirty question here;

I'm looking at setting the Pi up in my garage which gets very hot on Summer afternoons, prolly around 35C maybe up towards 45C at the worst, am I likely to need a cooling fan for it under these conditions, running 24/7? If so, will one of those little USB bendy fans do the trick?

Thanks for any help!

[dukla2000]

The entire card is disipating around 3W, hardly a thermal issue. I figure any fan is excessive.

[Joe Schmoe]

I don't think the implication was that the Pi would generate (noticeable) heat itself.

Rather, the implication was that the environment in which it (the Pi) was to be deployed was itself hostile - and that thus it seemed like a good idea to keep it (the Pi) cool.

9+6

[PotatoHandle]

Yeah, that's more it; I remember my Pentium III from many, many years ago with similar specs to the Pi, shut down at around 60C; since it's a smaller device I thought it'd be worth making sure it will be alright in that kind of environment. If it doesn't like running at 45-55C for prolly half of it's life, then I might need to get creative. (I'm thinking of putting the Pi inside the wall space, haha)

[reallynotnick]

PotatoHandle said:


Yeah, that's more it; I remember my Pentium III from many, many years ago with similar specs to the Pi, shut down at around 60C; since it's a smaller device I thought it'd be worth making sure it will be alright in that kind of environment. If it doesn't like running at 45-55C for prolly half of it's life, then I might need to get creative. (I'm thinking of putting the Pi inside the wall space, haha)


Wait is it 35-45C or 45-55C? I can't imagine your garage gets up to 55C, but who am I to know, I live in Minnesota.

[WereCatf]

To the OP: I don't think 45C is too much for RPi to operate in, but if you feel like it you should get by with just using passive cooling. You could just get a regular CPU cooler and remove the fan from it, that would already be plenty for RPi. Especially if you get one with copper heatpipe or two.

In fact I personally would prefer passive cooling anyways over active cooling in your situation: garages tend to get dusty so the fan could eventually grind to a halt due to dust, or due to it losing its bearings, and since it sounds like you plan to place it so that you don't always keep it on eye it could overheat before you notice that the fan isn't operational anymore. Ie. passive cooling is more reliable, it doesn't require you to keep an eye on it. Not to mention it also consumes less energy.

Something along the lines of http://img.diytrade.com/cdimg/.....or_AMD.jpg should be plenty and as you can see, you can remove the whole fan by just taking off the 4 screws located at corners.

If you were really paranoid about it you could use http://www.legitreviews.com/im.....ds_001.jpg or similar, but then you'd really have to be careful about how you place it: it weighs so much that it could bend or break your RPi board if the board has to support all that weight.

[kme]

WereCatf said:


To the OP: I don't think 45C is too much for RPi to operate in, but if you feel like it you should get by with just using passive cooling. You could just get a regular CPU cooler and remove the fan from it, that would already be plenty for RPi. Especially if you get one with copper heatpipe or two.


Where would you place this cooler? It's a PoP, so all you have access to is the RAM package surface and cooling that will have only marginal effect on the CPU/GPU.

I think you are inventing problems. These SoCs are designed to take beating.

[WereCatf]

kme said:

Where would you place this cooler? It's a PoP, so all you have access to is the RAM package surface and cooling that will have only marginal effect on the CPU/GPU.
If I really had to cool the thing, I'd cool it from beneath it, not on top of it.



I think you are inventing problems. These SoCs are designed to take beating.


I wasn't the one looking for cooling, I merely replied here. These kinds of things do not heat up easily and even if they do they'll still easily handle 60C, so I see no point in bothering with cooling, but it is still polite to answer the question posed nevertheless.

[kme]

WereCatf said:


kme said:


Where would you place this cooler? It's a PoP, so all you have access to is the RAM package surface and cooling that will have only marginal effect on the CPU/GPU.


If I really had to cool the thing, I'd cool it from beneath it, not on top of it.


That would be very difficult too: http://dmkenr5gtnd8f.cloudfron.....236530.jpg

It is also polite to point out if an anticipated problem/solution isn't feasible at all.

[PotatoHandle]

reallynotnick said:


PotatoHandle said:


Yeah, that's more it; I remember my Pentium III from many, many years ago with similar specs to the Pi, shut down at around 60C; since it's a smaller device I thought it'd be worth making sure it will be alright in that kind of environment. If it doesn't like running at 45-55C for prolly half of it's life, then I might need to get creative. (I'm thinking of putting the Pi inside the wall space, haha)


Wait is it 35-45C or 45-55C? I can't imagine your garage gets up to 55C, but who am I to know, I live in Minnesota.


The garage prolly gets to around 35-45C but I suspect the device will generate at least a little heat itself, so I'm expecting the CPU temperature to be at least a little higher, an extra 10C is a completely arbitrary guess though.

The consensus seems to be that it'll be fine though, so thanks for all the replies! I'll begin the cabling this weekend!

[cnxsoft]

The Raspberry Pi foundation should be able to answer your question, since they've probably done some reliability testing in some special ovens.

[Robert_M]

I think if I were in your shoes, I'd place the Pi in one of the openings of a cinder block. Those things always seem to be a little cooler even in a hot garage. It might give a little microclimate for you Pi that's a few degrees cooler than ambient temperature.

[gsh]

BCM2835 is around 40 degrees centigrade per watt and the TjMAX rating of the chip is 85.

We dissipate something like a watt peak (thats with the 3D and the ARM running flat out...) and theoretically could go higher if we added in the video encode / decode as well but that use case is unlikely...  So Max ambient temperature is somewhere in the range of 85 - (1 * 40) = 45 degrees (centigrade)

This assumes that the external temperature is ambient and that you don't box it...

I guess 55 might be OK, we do have a temperature sensor inside so could probably tell you what the junction temperature actually is and hold back on the maximum frequency is stay below 85

Gordon

[Gert van Loo]

We have run them a prolonged time at 80 degr. Celsius in an oven with no problems.

The Theta-J with an airflow of 0m/sec is ~35 C/W. This is with a PoP memory on top. So with a 1W power consumption your max. ambient temperature is about 120-35=85 Degrees Celsius.  (185 F) By that time you should probably worry about other things in your garage.

(Sorry Gordon, I have the official BCM2835 thermal report in front of me. I can only assume your TjMAX 85 is confused with Ambient Max of 85)

[mgmt_idiot]

Did you run it in the freezer too? It got down to minus 17C in my garage last year. My freezer does minus 21C.

I'm also interested in humidity tolerances.

[Gert van Loo]

It is specified for -40. IF it is already running, the internal temperature would be higher. So theoretical you could go below -40C. Lets say -60C.

Again, you probably should worry about other things in your garage. e.g. if you motor block as not torn because of the frozen cooling liquid.

[davidgoodenough]

It is also a matter of the enclosure for the board.  I run some small i386 based systems (Wrap boards from Microtik) in small enclosures outdoors, and provided they are continuously powered they keep themselves warm.  The most problematic component is actually the oscillator crystal - if the power fails and then comes back on when the temerature is too low - it will not start to oscillate.

[treczoks]

Another issue apart from the chip is the board itself, which might produce cracks in the copper if it gets too cold.

[Burngate]

Gert said:

The Theta-J with an airflow of 0m/sec is ~35 C/W. This is with a PoP memory on top. So with a 1W power consumption your max. ambient temperature is about 120-35=85 Degrees Celsius.  (185 F)
It is specified for -40.
Weyhey! real figures!

Can this be put in the FAQ (and/or wiki) beside the Pi mechanical data? I'd do it myself but ...

[FeepingCreature]

I used to cool my overheating router by putting it in a plastic bag and the plastic bag in a bucket of water. Not sure if that applies here.

[alexandru.cucu]

@FeepingCreature

How about submerging the thing in mineral oil?

[liz]

Of course, the BCM2835 isn't the only temperature sensitive part in there - the LAN chip is qualified from 0C-70C.

[mgmt_idiot]

Oh well, so much for the idea of leaving some in my garage...

Liz, is there a data sheet for the overall RasPi with this stuff on it?

[liz]

Not yet (there will be soon, though). I'm working on a redo of the FAQ at the moment, with some help from Scep; as much of this sort of info as I can find will be in there.

[kme]

mgmt_idiot said:


Oh well, so much for the idea of leaving some in my garage...


I wouldn't worry much. These chip fellas are paranoid in the first place and if you just have some sort of a case you won't get much below zero - if at all.