Raspberry Pi4B (4GB) plus POE Hat - Review

Table of contents

RoadTest: Raspberry Pi4B (4GB) plus POE Hat

Author: jasonwier92

Creation date:

Evaluation Type: Development Boards & Tools

Did you receive all parts the manufacturer stated would be included in the package?: True

What other parts do you consider comparable to this product?: A PoE injector and splitter would also work, but the CPU fan would not be included

What were the biggest problems encountered?: Access to pins and camera

Detailed Review:



First of all I would like to say thank you to Element 14 for picking me for this Road Test to review this Raspberry Pi 4 and PoE hat.  The PoE hat allows the Raspberry Pi to be powered via Power over Ethernet or PoE. I have found this product to work perfectly for my use case.




Raspberry Pi 4B is the latest Raspberry Pi computer to be released at the time of this review.  The Raspberry Pi is a low cost, small, about the size of a credit card, consumer based computer.


PoE Hat is an additional board that can plug into the Raspberry Pi 3B+ or 4B and power the device from power over the Ethernet cable.  This device also comes with a CPU fan that is controlled over I2C and turns on when the CPU temperature reaches a set threshold.


Ubiquiti ToughSwitch Pro is a 8 port switch that is well suited to be used in non-ideal conditions. It is a managed 8 port switch that has PoE and supports VLANs.  This made it the ideal test for a Raspberry Pi with a PoE hat.


A Bit About PoE


There are different PoE Standards out there, but the PoE Hat works with IEEE 802.3af at 48V.  802.3af has been around since 2003 and I had a switch that supported it.



At my home office, I use PoE on my ToughSwitch to power two access points for my wireless network and a VoIP phone.  I used to use PoE injectors but found them to be clunky and problematic.  Also the TouchSwitch gives me the option to power cycle what ever is plugged into it. Very helpful when the device is in a hard to reach position, which is a good reason to use PoE. I also employ PoE for my camera and access point at my tower location (I have an 80 foot tower at the back of my property so that I could get Internet and the WISP provides Internet to my neighbors). Both of these use PoE injectors still, but some day I hope to get a PoE switch at my tower location.




Setup was straight forward.  I setup my ToughSwitch to have 48V PoE on the port (7) for the Pi and PoE Hat.  Here is what that looks like:



I have the port labeled for ease of future management. This interface also allows me to power cycle any device.


The PoE Hat uses the GPIO header on the Raspberry Pi 3B+ and 4B plus the 4 pins designed to be used with the PoE Hat.




And the PoE Hat has matching pins.




Also the PoE Hat comes with 4 studs and screws for securing the Pi and Hat together. This is where my first concern arised, because one of the many great feathers of the Raspberry Pi is the GPIO pins.  So imagine this Pi was deployed in a remote location to monitor temperature or power.  The GPIO pins are all consumed by this Hat.  One solution is to buy long header pins, because the Hat has pass-thru style header. That product can be ordered here:




I chose not to use this for testing, because I do not know what my future plans are for this unit yet.


One other concern I had using the PoE Hat with the RPi 4B was the fact that the RPi4 4B specs call for a 3A power supply.  The PoE Hat says it supplies up to 2.5V.  During my testing I monitored this to see if was a problem and it did not seems to be an issue. I even plugged in a 2.5 Hard Drive (spinner) via USB and transferred a bunch of files and that did not see to have issue.


For my testing I setup a SD card with the latest Rasbian Lite and the the system powered right on and worked. It was really easy to setup and get working, but I did not expect any different.  I did plug in the HDMI to a monitor to do some initial setup.




The RPi 4B and PoE Hat worked like a charm.  Never did I have issues and it was nice to be able to move it to where ever the Ethernet cord would go and now powering it off. My first test was to put NGINX on it and test it as a web server.  This I install collectd and had to report back to my collectd server. One thing that I setup was CPU temperature and here is what that looked like.




Yes, when I checked today the collectd server was off and I am not sure why.  The fan on the kept the unit cool and did not make any noticeable noise. Early June I was getting ready to write this review and did an update to the system. After the update and reboot, the CPU temperature ran about 8 degrees less and that is a good amount less.  Here is a chart showing system load.  Not sure what I was doing at the start to generate so much load, but it was really working hard at the start.









I did have a few issues. First of all the power output of 2.5A might be an issue at some point, so that could be an issue.  Like I said, it never caused an issue while I was running it.


Having to use the GPIO extenders would be an issue.  I will get some and test it when deployed and now that I know it is stable, I will be using it in some function around the house or outside.  The other concern with the extensions would be the studs would not be long enough to secure the PoE Hat to the RPi.


Just a few days ago after I updated with a "apt full-upgrade" I tried the Raspberry Pi NoIR v2 camera with this setup. The PoE Hat had to be removed and the ribbon cable inserted into the RPi, which was not hard, but just was an extra step in getting it up and going. Then when I tried to use the camera with motion it would say it cannot access the camera.  Also "raspistill" would not  return to a command prompt or produce an image.  So after much testing, re-inserting the ribbon, etc, I put the camera on another RPi 4 that I have and it worked fine.  Not sure it is related to the PoE Hat, but someday soon I will find out. The reason I even tried this, is because of a project I need to get moving on now and I thought that the PoE RPi would be a perfect remote camera. 




All in all the PoE Hat is a great addition to the RPi and I feel would have some very good use cases.  One of them that I would be interested in is a small weather station mounted in a remote location or on my tower.  It would be nice to have to  only run an Ethernet cable to the station.  Another would be the one I mentioned already and that would be a remote camera. 


Again, but thank you to Element14 for the chance to road test this PoE Hat and the Raspberry Pi 4B.  I will be using it for future projects and will share how that goes.  If I can get it to work with my NoIR Camera, then maybe it will be used for that project. That project will be a garden defense project.  The deer at all my bean plants last year, so this year I thought it would be good to have a camera to detect deer and when detected trigger a device to drive them away.  This should get fun!  I was thinking Motion or TensorFlow for seeing the deer!