Pi 3 B+: Needs Cooling?

Hi,

if I search for cases for my RasPi 3 B+, I found the most cases has additional heat spreader and fan. It is fact that a RasPi 3 B+ needs additional cooling? (Fans are noisy ...)

Bernd

Depends on what you're doing with it. IME if you're playing video that'll push the temperature up, but everything else is fine.

Thx,

I'll cut the fan cable ;-)

Bernd

Not sure. Even idling several parts in mine got too hot to touch. I have bought a set of stick-on heatsinks and feel better now. A fan seems overkill, but a closed case may keep the warmth in.

Cheap passive cooling (and an open/half open case) is good enough for 99%

Or, for a case with a ventilation hole on top, disable the fan and fit a cardboard tube of at least the diameter of the vent hole to use the chimney effect for cooling. Not sure what size the tube would need to be

- 50cm @ 50mm diam - but its something you can try at zero cost and with almost no preparation.

And never forget that ventilation at the top is useless without corresponding openings at the bottom and vice versa. I say this this, because I've seen that kind of silliness. Often there are openings at the bottom, where you can't see them, but a nice, shiny, and totally closed top.

Hi-speed fans are noisy, low-speed ones aren't.

Fit a 40mm 5V fan (eg CPC MF67761, lots of blade area, quoted 27 dBA) that'll be pretty quiet connected directly to 5V.

Want quieter feed it via transistor from a GPIO producing a PWM signal under software control. Can arrange for it to only run when required and only as fast as needs be. Note if going from stopped to moving it might need a brief full whack burst to get it going. Donno how easy getting the CPU temp is (or isn't).

Not always. I have a tiny fan on my 3B+ and it is just audible when run off 5V, but inaudible at 3V3. The lower voltage still gives sufficient airflow to prevent thermal throttling on any workload I give it, where as in a case without a fan, it quickly runs away.

---druck

Fair comment - and equally applicable to fans as well as chimneys.

Just how big is your Raspberry Pi case?

---druck

On Fri, 11 Jan 2019 21:39:28 +1300, snipped-for-privacy@f1.n50.z2.binkp.net (Vince Coen) declaimed the following:

Pardon? A 12 INCH fan for a board that is barely 3 inches on the long side?

I, for one, can't spare a microwave oven for a credit card computer.

Am 11.01.19 um 10:36 schrieb Bernd:

Thx, for your comments. Meanwhile I have found how to measure the temp from the RasPi. This and the tip to use a 5V fan but connect to 3.3V does the trick.

Thx for the ideas!

Bernd

Bernd wrote, on 12-01-2019 09:20:

Readable output, not directly useful in scripts: $ vcgencmd measure_temp temp=46.2'C

Value in millidegrees: $ cat /sys/class/thermal/thermal_zone0/temp

Value in degrees rounded down, so 47.9 becomes 47: $ echo $(($(cat /sys/class/thermal/thermal_zone0/temp)/1000))

Value in degrees with one decimal, using bc: $ echo "scale=1;$(cat /sys/class/thermal/thermal_zone0/temp)/1000" | bc

The same thing without bc: $ vcgencmd measure_temp | cut -d= -f2 | cut -d' -f1

(The decimal separator is not localised for any of these.)

On a sunny day (Sat, 12 Jan 2019 10:13:49 +0100) it happened "A. Dumas" wrote in :

Degrees Kelvin?

Here's something new for you to learn: the unit symbol is K, the unit name is kelvin, the person is Kelvin.

On 12/01/2019 10:37, Jan Panteltje wrote: []

Celcius, with a power of 10 multiplier.

Indeed. :-)

On a sunny day (Sat, 12 Jan 2019 11:21:13 +0000) it happened David Taylor wrote in :

Wrong

Just add 273.15 But can he do that ;-)