Juggler00
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PoE HAT - noisy fan

Sun Jan 06, 2019 8:09 pm

I have the official Raspberry Pi PoE HAT and am running a fully-updated Raspbian. I am noticing that the fan on the PoE HAT is very noisy. It appears to spin up to 100% every 10-20s, run at 100% for ~60s then repeat.

I did some searching on the forums and have seen some comments on how to alter this behaviour. I’m looking for the actual, proper way to do this. Can anyone help?

ShiftPlusOne
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Re: PoE HAT - noisy fan

Mon Jan 07, 2019 6:57 am

Out of curiosity, what's the ambient temperature of the room and what's the pi doing when the fan kicks in, if anything?

Edit config.txt and add the following line:

Code: Select all

dtparam=poe_fan_temp0=80000,poe_fan_temp0_hyst=5000,poe_fan_temp1=82000,poe_fan_temp1_hyst=2000
That should change the behaviour so that the fan turns on at 80C, turns off when it comes back down to 75C. If the temperature reaches 82C it will go full blast until it drops back down to 80C. You can play with the values and adjust them so that they suit you.

https://github.com/raspberrypi/firmware ... ADME#L1649
Juggler00 wrote: It appears to spin up to 100% every 10-20s, run at 100% for ~60s then repeat.
It shouldn't go to 100% right away, but let's check if the instructions above help before diagnosing further.

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Imperf3kt
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Re: PoE HAT - noisy fan

Mon Jan 07, 2019 11:44 am

I thought the fan could only be controlled between 60 and 70 degrees. Is it now possible to force it to any desired value?
55:55:44:44:4C
52:4C:52:42:41

ShiftPlusOne
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Re: PoE HAT - noisy fan

Mon Jan 07, 2019 12:21 pm

The behaviour of the fan could always be defined by the user. The most recent change (a few months back) was to make the temperature and hysteresis values easily adjustable through config.txt, to cover most use cases without having to rebuild a device tree overlay.

Juggler00
Posts: 6
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Re: PoE HAT - noisy fan

Mon Jan 07, 2019 2:35 pm

The room is at 21ºC, so nothing extreme. I'm running ser2net on the Pi so that my instance of HomeAssistant sees the USB z-wave stick attached to the Pi as a local device. This does increase the network traffic, so I'm wondering if that could be causing the "freak out"?

I've made the changes to config.txt; so far so good. Thanks!!!
ShiftPlusOne wrote:
Mon Jan 07, 2019 6:57 am
Out of curiosity, what's the ambient temperature of the room and what's the pi doing when the fan kicks in, if anything?

Edit config.txt and add the following line:

Code: Select all

dtparam=poe_fan_temp0=80000,poe_fan_temp0_hyst=5000,poe_fan_temp1=82000,poe_fan_temp1_hyst=2000
That should change the behaviour so that the fan turns on at 80C, turns off when it comes back down to 75C. If the temperature reaches 82C it will go full blast until it drops back down to 80C. You can play with the values and adjust them so that they suit you.

https://github.com/raspberrypi/firmware ... ADME#L1649
Juggler00 wrote: It appears to spin up to 100% every 10-20s, run at 100% for ~60s then repeat.
It shouldn't go to 100% right away, but let's check if the instructions above help before diagnosing further.

80ov
Posts: 2
Joined: Tue Feb 26, 2019 11:18 am

Re: PoE HAT - noisy fan

Tue Feb 26, 2019 11:26 am

ShiftPlusOne wrote:
Mon Jan 07, 2019 12:21 pm
The behaviour of the fan could always be defined by the user. The most recent change (a few months back) was to make the temperature and hysteresis values easily adjustable through config.txt, to cover most use cases without having to rebuild a device tree overlay.
On what the kernel does it work? I have 4.14.9x. After adding a line
dtparam=poe_fan_temp0=80000,poe_fan_temp0_hyst=5000,poe_fan_temp1=82000,poe_fan_temp1_hyst=2000
in to /boot/config.txt - raspberry did not boot after reboot.

ShiftPlusOne
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Re: PoE HAT - noisy fan

Tue Feb 26, 2019 4:53 pm

80ov wrote: On what the kernel does it work? I have 4.14.9x. After adding a line
dtparam=poe_fan_temp0=80000,poe_fan_temp0_hyst=5000,poe_fan_temp1=82000,poe_fan_temp1_hyst=2000
in to /boot/config.txt - raspberry did not boot after reboot.
Should work on all relatively recent kernels.

I've just tested it with rpi-update a08ece3 (4.14.98) and it seems to work.

Unrelated to this, but I've just noticed that config.txt dtparam lines seem to have a character limit. poe_fan_temp1_hyst=2000 is cut off, so you may wish to split it into two lines:

Code: Select all

dtparam=poe_fan_temp0=80000,poe_fan_temp0_hyst=5000
dtparam=poe_fan_temp1=82000,poe_fan_temp1_hyst=2000

80ov
Posts: 2
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Re: PoE HAT - noisy fan

Tue Feb 26, 2019 5:26 pm

ShiftPlusOne wrote:
Tue Feb 26, 2019 4:53 pm
80ov wrote: On what the kernel does it work? I have 4.14.9x. After adding a line
dtparam=poe_fan_temp0=80000,poe_fan_temp0_hyst=5000,poe_fan_temp1=82000,poe_fan_temp1_hyst=2000
in to /boot/config.txt - raspberry did not boot after reboot.
Should work on all relatively recent kernels.

I've just tested it with rpi-update a08ece3 (4.14.98) and it seems to work.

Unrelated to this, but I've just noticed that config.txt dtparam lines seem to have a character limit. poe_fan_temp1_hyst=2000 is cut off, so you may wish to split it into two lines:

Code: Select all

dtparam=poe_fan_temp0=80000,poe_fan_temp0_hyst=5000
dtparam=poe_fan_temp1=82000,poe_fan_temp1_hyst=2000
Great, it worked!
Спасибо!

ShiftPlusOne
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Re: PoE HAT - noisy fan

Tue Feb 26, 2019 6:00 pm

80ov wrote: Great, it worked!
Спасибо!
Glad to hear it.

Незачто!

Toorms
Posts: 12
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Re: PoE HAT - noisy fan

Fri Mar 20, 2020 7:45 am

Hey Community,

I'm a little bit confused right now. For what we have two fans in the config file? fan0 and fan1 - usually the PoE HAT has only one fan on top of the HAT.

Code: Select all

dtparam=poe_fan_temp0=60000,poe_fan_temp0_hyst=3000
dtparam=poe_fan_temp1=65000,poe_fan_temp1_hyst=3000
Can anybody explain this? Thanks.

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rpdom
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Re: PoE HAT - noisy fan

Fri Mar 20, 2020 9:33 am

Toorms wrote:
Fri Mar 20, 2020 7:45 am
I'm a little bit confused right now. For what we have two fans in the config file? fan0 and fan1 - usually the PoE HAT has only one fan on top of the HAT.
I cant see two fans in that file. Just one fan with two different temperature trigger points.

bpaoz
Posts: 3
Joined: Fri Mar 20, 2020 10:05 am

Re: PoE HAT - noisy fan

Fri Mar 20, 2020 10:21 am

Like the OP I have 3 x Raspberry Pi 4 units with official POE HAT modules to act as home automation radio bridges throughout a house and find the noise generated by the fans to be very loud. The workload of running ser2net or usb/ip isn't much and even just a base operating system install without any connected users causes the POE HAT fan to spin up for 15 seconds every 50 seconds.

The configuration settings discussed in this thread do work, but eventually the fan has to go on to cool the SOC at some point and the sudden noise is so noticeable that you cannot put the Pi in any room where people are likely to be. I'm unsure what use case was envisaged for the POC HAT as designed, as every other POE device I have deployed here at home is completely silent (ie IP cameras, wireless access points etc).

Is there some way to switch the fan permanently on, perhaps at a very low RPM so it makes less noise?

Alternately has anyone had success replacing the fan with another model that perhaps isn't as noisy?

Or has someone found some settings / configuration / workaround where the fan won't switch on and it doesn't fry the Pi?

I'm happy to buy extra parts to solve this as I'd really prefer POE to work. But I've ordered conventional heat sinks, cases and USB power supplies given the POE HAT doesn't seem feasible if you need the unit in a typical household room.

bpaoz
Posts: 3
Joined: Fri Mar 20, 2020 10:05 am

Re: PoE HAT - noisy fan

Tue Mar 24, 2020 6:39 am

A short update following further research today.

The fans inside the official POE HATs that I have here are Sunon MF25060V2 units (data sheet). The rated noise is 18.0 dB, and I couldn't readily find on Mouser Electronics any compatible replacement fans at a materially lower rated noise.

Fortunately there may be a software solution though. The existing rpi-poe overlay provides 3 temperature setpoints which operate the fans at 0, 150 and 250 PWM. Pull request 3493 adds a further 2 temperature setpoints at 31 and 63 PWM.

Hopefully a merged PR 3493 will resolve the issue of lightly-loaded Pis being cooled sufficiently.

jahboater
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Re: PoE HAT - noisy fan

Tue Mar 24, 2020 9:19 am

bpaoz wrote:
Fri Mar 20, 2020 10:21 am
Like the OP I have 3 x Raspberry Pi 4 units with official POE HAT modules to act as home automation radio bridges throughout a house and find the noise generated by the fans to be very loud.
Are you running the latest Raspbian updates?
The recent firmware keeps the temperatures very low and there should be no need for any forced cooling with any load.
What does the load average look like (uptime) and why is it getting so hot?

This cheap (£1.57) stick on heat reduces the temp further (mid 60C's running the cpuburn stress test) and is silent of course.
https://uk.rs-online.com/web/p/heatsinks/7500951/

I have just tried this little case:
https://www.mechatronicsart.com/mechatr ... nclosures/
which reduces the cpuburn temp down to around 56C.

For light loads the temp remains in the 30C's
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bpaoz
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Re: PoE HAT - noisy fan

Wed Mar 25, 2020 8:26 am

Are you running the latest Raspbian updates?
Raspbian Lite 2020-02-14 (kernel 4.19.97-v7l+).
What does the load average look like (uptime)?

Code: Select all

 08:06:49 up  1:44,  1 user,  load average: 0.00, 0.00, 0.00
Why is it getting so hot?
The official POE HAT covers the entirety of the Pi and this impedes both convection cooling of the SOC or the introduction of a passive heatsink. So you are reliant on the POE HAT fan, and unfortunately it's noisy at the PWM settings in the currently-released overlay.

However am pleased to now confirm that PR 3493 comprehensive resolves this issue.

manuel
Posts: 7
Joined: Sat Jul 06, 2013 11:33 am

Re: PoE HAT - noisy fan

Sun Mar 29, 2020 8:06 am

Wow, this is great. Now the fan rotates on a very low noise level 8-)

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