LewisDexter
Posts: 5
Joined: Thu Mar 09, 2017 9:00 am

Raspberry Pi 3 B+ PoE Hat fan

Thu Aug 23, 2018 1:48 pm

On what temperature is the fan on the PoE Hat working. Do I have to enable something to use the fan on PoE Hat? Because it is never on.

ShiftPlusOne
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
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Re: Raspberry Pi 3 B+ PoE Hat fan

Thu Aug 23, 2018 1:51 pm

LewisDexter wrote:
Thu Aug 23, 2018 1:48 pm
On what temperature is the fan on the PoE Hat working. Do I have to enable something to use the fan on PoE Hat? Because it is never on.
You need to make sure your firmware is up to date:

Code: Select all

sudo apt update
sudo apt dist-upgrade
It should come on at 45C, speed up at 50C and be at full speed above 55C.

ShiftPlusOne
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
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Re: Raspberry Pi 3 B+ PoE Hat fan

Thu Aug 23, 2018 1:51 pm

ShiftPlusOne wrote:
Thu Aug 23, 2018 1:51 pm
LewisDexter wrote:
Thu Aug 23, 2018 1:48 pm
On what temperature is the fan on the PoE Hat working. Do I have to enable something to use the fan on PoE Hat? Because it is never on.
You need to make sure your firmware is up to date:

Code: Select all

sudo apt update
sudo apt dist-upgrade
reboot
It should come on at 45C, speed up at 50C and be at full speed above 55C.

n67
Posts: 938
Joined: Mon Oct 30, 2017 4:55 pm

Re: Raspberry Pi 3 B+ PoE Hat fan

Thu Aug 23, 2018 2:28 pm

It should come on at 45C, speed up at 50C and be at full speed above 55C.
That seems awfully conservative. The standard wisdom on this forum seems to be that you shouldn't start worrying at all about temperature until at least 60. And shouldn't really be worried worried [sic] until you hit 70.

My machines routinely run in the 50s - occasionally hitting the low 60s.

BTW, can anyone recommend an alternative fan rig for the Pi - that does what the PoE Hat one does, but (obviously) doesn't include the PoE stuff? One could, of course, rig something up themselves, but I'm curious about off-the-shelf solutions.
"L'enfer, c'est les autres"

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hippy
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Re: Raspberry Pi 3 B+ PoE Hat fan

Thu Aug 23, 2018 2:32 pm

n67 wrote:
Thu Aug 23, 2018 2:28 pm
It should come on at 45C, speed up at 50C and be at full speed above 55C.
That seems awfully conservative.
There appears to be some detail on how to change settings here ...

https://www.raspberrypi.org/forums/view ... 0#p1356682

ShiftPlusOne
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Re: Raspberry Pi 3 B+ PoE Hat fan

Thu Aug 23, 2018 2:37 pm

Since the pi throttles from 1.4GHz to 1.2GHz at 60C, that was chosen as the point to try to avoid going over.
hippy wrote:
Thu Aug 23, 2018 2:32 pm
There appears to be some detail on how to change settings here ...

https://www.raspberrypi.org/forums/view ... 0#p1356682
And this post shows how to disable the fan altogether or set a static temperature:
https://www.raspberrypi.org/forums/view ... 5#p1354556

LewisDexter
Posts: 5
Joined: Thu Mar 09, 2017 9:00 am

Re: Raspberry Pi 3 B+ PoE Hat fan

Thu Aug 23, 2018 4:30 pm

Thanks, the firmware update solved it

n67
Posts: 938
Joined: Mon Oct 30, 2017 4:55 pm

Re: Raspberry Pi 3 B+ PoE Hat fan

Thu Aug 23, 2018 4:53 pm

Since the pi throttles from 1.4GHz to 1.2GHz at 60C, that was chosen as the point to try to avoid going over.
Interesting. I do not have a 3B+ (yet).

For all previous models, the CW has always been that it doesn't throttle until it hits 80.
"L'enfer, c'est les autres"

G fytc hsqr rum umpbq rm qyw rm rfc kmbq md rfgq dmpsk:

Epmu Sn!

J lnacjrw njbruh-carppnanm vxm rb mnuncrwp vh yxbcb!

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Imperf3kt
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Re: Raspberry Pi 3 B+ PoE Hat fan

Thu Aug 23, 2018 9:45 pm

n67 wrote:
Thu Aug 23, 2018 4:53 pm
Since the pi throttles from 1.4GHz to 1.2GHz at 60C, that was chosen as the point to try to avoid going over.
Interesting. I do not have a 3B+ (yet).

For all previous models, the CW has always been that it doesn't throttle until it hits 80.
That is still the case with the 3B+ - the first throttling at 60℃ is a soft throttle, it only removes the overclock. The Pi won't throttle further, until ~82℃
55:55:44:44:4C
52:4C:52:42:41

fliegema
Posts: 1
Joined: Fri Apr 17, 2020 3:46 am

Re: Raspberry Pi 3 B+ PoE Hat fan

Fri Apr 17, 2020 4:02 am

Dear All,

first of all, thank you for the previous comments, it helped me to narrow down the troubleshooting.

Issue:
POE hat fan starts at 50C even though, the command's Threshold is set to 80C. I used the same command since 1.5 years and never heard the fan afterwards 8-)

Since the firmware update to 4.19.114-v7+, the fan on the POE hat will always turn on for 10sec (sounds like full speed) and turn off again. In between you can hear some short high pitch sounds (which it always does when you boot).

Room ambient temperature is roughly around 30C and the command:

Code: Select all

vcgencmd measure_temp
shows: all day long temperatures between 49C - 51 C.

I read in the following thread that the standard threshold for the fan is 50C, which would explain why it suddenly turns on again.

viewtopic.php?p=1356682#p1356682

Details:
Raspberry Pi 3 Model B Plus Rev 1.3
stretch
4.19.114-v7+ #1303
Pi is mounted behind a screen, without case, lifted for better airflow

command used:
/boot/config.txt

Code: Select all

dtparam=poe_fan_temp0=80000,poe_fan_temp0_hyst=5000
dtparam=poe_fan_temp1=82000,poe_fan_temp1_hyst=2000
I am absolutely in the end of researching on google searches and have no further clue where is the setting, which tells the fan to turn on with its standard config. The fan has been also unmounted and cleaned.

Since the above command worked flawless over the time, I may give the following a try:
https://github.com/raspberrypi/linux/bl ... verlay.dts
has anyone done this before?

Any suggestions from the forum are very much appriciated.

Cheers

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