FlightAware Discussions

Overheated Pi


#1

I’ve just burned out another Pi.

The last time I checked on it, it was reporting 83C, because the fan had failed (it was three months old).
Apparently this caused the adhesive to go soft and the heatsink slid off and caused a short circuit on the Pi - resulting in another dead Pi.

I’ve ordered some ceramic heatsinks (non-conductive), but the adhesive probably won’t be any better.

Anybody else coping with a hot environment successfully?


#2

You could always go with 2 component thermal adhesive.
That for sure won’t come off.
(cleaning the surfaces with isopropanol or alcohol so they are free of any oils/fat sure helps the glue stick as well)
Something like this: (https://www.amazon.com/Arctic-Alumina-Thermal-Adhesive-5g/dp/B0009IQ1BU)

Also a fan failing after 3 month seems like particularly bad luck or a particularly bad fan.

Good luck!


#3

Do you have a cooler location for the Pi? Air-conditioned?


#4

Yep, that’s probably the best way of keeping the heatsinks on.

It is (to pull a line from a film), in the middle of a sheep paddock.
It runs on a solar panel and batteries so A/C isn’t practical.
On the plus side, it’s a great place for a radio receiver.

(it’s actually a cattle paddock, but I’d loose the film ref!)


#5

Could also be that your power supply was unstable or delivering too high a voltage.

Or are you sure about the short?

Also using a secondary box that is open at the bottom will keep the first box much cooler in direct sunshine. (doesn’t need to be waterproof if the inner box is)


#6

The Pi was wearing a Geekworm Power Hat, so the DC-DC should have kept the supply under control.

Pretty sure about the short - it had been working fine. When it failed, I found the heatsink had slid off the CPU. The Pi was mounted veticly to help with convection.

The ‘box’ is insulated with foam and ply sheet on the N, E and W sides. The south side is uninsulated for cooling (It is 36º south).
The ‘box’ is 2m x 1.5m x 0.7m (HxWxD) so I don’t think heating by the Pi contributed much.


#7

Standoff sunshields with air being able to circulate between the box and the sunshield would probably be a good addition :slight_smile:
(Maybe think about adding an extra shield just on the top?)

But changing such a large box is quite the hassle.
I would probably just use a larger fan, those small fans like to fail more i think.
Not sure how to mount a bigger fan though, maybe just make it blow up with the vertical pi mounted above.
Of course you are also concerned about power usage by the fan so i can see why you would use a smaller fan.
Still getting a quality 4x4 cm fan is not easy i believe, 8x8 cm fans are easier to get.


#8

So you opened the South side to allow… rain inside too?


#9

Ah - the roof has a 200W solar panel shading it. It’s mounted with a gap to allow air to circulate.

Agree that small fans are temperamental at best. A slow spinning large fan will move more air and last longer.

No, the south side isn’t open, just not insulated.
(the south side also has a door, so you can walk in and get out of the rain!)

Occasionally it does attract visitors (finger for scale)


#10

Mine lives out in my hangar in the Houston area, which is neither insulated nor climate-controlled. It’s been running out there for a couple years now, basically since we moved in.

My unit is pretty old, but when I built it I bought a case with an integrated fan, and that fan still works to my knowledge. I haven’t actually checked it in a while I’m just going by the fact that the thing is still feeding.

This is the case I used, though it’s not available on Amazon any more: https://www.amazon.com/gp/product/B00MQQQO9W/ref=oh_aui_search_asin_title?ie=UTF8&psc=1


#11

I have to constantly remember myself that your South is like my North. And your Summer is my Winter.
Here we complain that’s too cold this time of the year.


#12

In the few years I have been running multiple Pi in the roof space three of the five fans which were bought from reputable Raspberry resellers have failed and several of the heatsinks have slid out of place.

No resulting short circuits and so far no Red Back Spiders

I am now changing over to mounting the Pi naked in a large box with plenty of ventilation and discarding the purpose built cases. It appears I will not need to force ventilate the large box.

I have one Pi mounted on an office building roof that is in direct sunlight in the mornings and I have not found a way to keep it cool. I now have permission from the building owners to mount it on the wall and put a shade panel in front which should suffice. It will be interesting to see if the extra 12 metres of coax makes a difference in numbers. Unfortunately I have a chronic back problem that will prevent me doing any antenna work for some months.

S.


#13

Thanks for your replies guys.
Houston gets warm, but I’ve had a couple of hot weeks this year up around 45°C (~113°F) (if I were a heatsink, I’d want to fall off too).

Clearly the quality of the components sold for Pis varies widely and care needs to taken when selecting.

Mounting the Pi without a case has merit - perhaps I need to look at water cooling! (Hmmm … perhaps not)

For those Stateside, our Redback is a close match to your Black Widow.


#14

Thinking outside the box, wondering if an exhaust fan (Or clever passive venting) for the structure might help- combined with some shade cloth to keep direct sun off the metal walls. ( if you didnt have solar panels mounted on top, a huge overall sun shade might be an idea.)

Any fan is going to move heated air off the Pi, but if there is no cooler intake air, temperatures are going to climb.

Can you cool the building with a sprinkler/ mister system on a timer ?


#15

Have you thought of cooling with a Peltier element?
Something like:
https://www.europeanthermodynamics.com/products/thermoelectric-modules/peltier-cooler

to put it in top of Pi box for example.


#16

Consumes quite a bit of power, not a good idea using battery power.

Anyway, a secondary sun shield in 3 directions would most likely solve your problem.
The insulation is probably just not good enough against direct sunshine.
(Or you need a vent near the roof and a vent near the bottom, so the inside doesn’t go more than 10C above ambient.)

If the Pi is higher up in that shed, it might help locating it more towards the bottom, should be cooler there.


#17

Interesting suggestions.
I’d need to leave a datalogger running for a while to measure internal and external temps to see if forced ventilation will provide any benefit (as we know, without a heat pump, it is not possible to cool below ambient).

Regarding the solar panel, I built the box specifically to hold up the panel (hence the roof angle) - that’s part of its purpose.

Water cooling the box would be an interesting project in its own right, but realistically, it wasn’t the heat that killed the Pi, it was the copper heatsink causing a short.
An alternative way to look at it is:

  • the heatsink adhesive should not have failed.
  • the fan shouldn’t have failed - if it hadn’t, the adhesive would have lasted (probably).

(For the want of a nail …)

There are some interesting comments on the Pi’s thermal managment where it describes what happens between 80~85°C (thereafter it threatens you with a red thermometer!)

Peltiers are great, but come with their own problems. They are power hungry, sure, but if it’s humid, you’ll get condensation on the board.


#18

Peltier enclosure cooler, with no outside air getting into the electronics enclosure. So no dust, no humidity.


#19

Hope this might help for anyone trying to reduce heat if running their Pi in a roof space.

I’m running my PiAware inside an old 12V battery box (with its cover on) mounted just under the peak of the roof tiles. The roof tiles are concrete type with no insulation under the tiles. I’ve fitted a good quality CoolerMaster 10cm PC cooling fan on the side of the box, which is blowing directly onto the Pi, FA dongle and power supplies for Pi and the fan. It connects to a 10’ LMR400 cable and a FA antenna mounted nice and high above the roof. I’ve drilled a heap of holes through various parts of the box to help with circulation. The fan is mounted inside a shroud with 10cm foil ducting running down to the ceiling to draw cool air in from the garage.

We’ve had some pretty hot days here recently, getting to around 36°C (close to 100°F). Checking the Pi via SSH, during the hottest part of the day it gets close to 60°C. Tonight it’s presently 29°C, Pi is reading 51°C.


#20

I think would be easier to install the Pi in the cooler garage and use a longer coax cable.
But that’s just me.