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Raspberry Pi4B (4GB) plus POE Hat - Review

Scoring

Product Performed to Expectations: 9
Specifications were sufficient to design with: 9
Demo Software was of good quality: 10
Product was easy to use: 9
Support materials were available: 5
The price to performance ratio was good: 9
TotalScore: 51 / 60
  • RoadTest: Raspberry Pi4B (4GB) plus POE Hat
  • Buy Now
  • Evaluation Type: Development Boards & Tools
  • Was everything in the box required?: Yes
  • Comparable Products/Other parts you considered: This was the only product evaluated. No product comparison analysis was done.
  • What were the biggest problems encountered?: Issues related to Integrating old and new technology.

  • Detailed Review:

    Commentary on Ratings:

    • Product Performed to Expectations: PoE Hat prevents the use of GPIO header without the use of a header extender. Using this PoE device will reduce network connection speeds.
    • Specifications were sufficient to design with: No details provided on PoE power supply requirements. Ordered from what was available in order catalogue.
    • Demo Software was of good quality: Full marks Not applicable.
    • Product was easy to use: Combination of Pi & PoE Hat exceed the size of a standard Pi case. Optional Heat sink, physical conflict with PoE Hat
    • Support materials were available: documentation consisted of brochure with pictures. No technical details provided.
    • The price to performance ratio was good: Canadian price for PoE Hat is $28. Canadian price for Pi4B power supply $11. Price not unreasonable considering the cost to plumb electrical.

     

    Introduction

    My thanks to the RoadTest Review committee and the product vendor for giving me an opportunity to test this product.

     

    One of the criticisms from RoadTest Review applicant's is their applications never gets selected. It is important to me, that there is full disclosure of my application The goal of this RoadTest Review is to comply with what is in the application.

     

    (c) Why did you apply for this particular roadtest?

    I’m am curious to explore power over Ethernet (PoE). I have a project that could benefit from the application of PoE. It would remove the requirement to run AC power.

     

    I have no experience with the is PoE technology. I have questions that I believe are best answered from doing. Assemble a Pi with PoE support, construct the cables, install power and make it work in an existing network. Nothing fancy just determining what is needed to make this PoE component work.

     

    I would like to install a system that uses the PoE module and answer some of my basic question. I manually construct cables, what if anything is required to support PoE regarding cabling? What about the length of cables? I'm assuming PoE is good over the maximum length of CAT5? No assumption, I will build a cable to test maximum. CAT5 cables with 568A & 568B pinout does it make a difference? What do you need for power when introducing a PoE device into a network? I have legacy network devices, what do I need to do to accommodate PoE? What are some reflective costs of investing in PoE?

     

    My proposal is to apply PoE on a Pi so I can understand some of the practical knowledge required in order to use the technology. I noticed the RoadTest suggests the PoE is Pi3B+ compatible. Of course the tests now have to be done using the Pi4 and a Pi3B+ I have as a Pi3+B for this testing.

     

    (d) What do you know about Power over Ethernet? (Please Explain)

    I have no experience using PoE. I have the skills to apply the technology once I gain the application knowledge. My initial investigation (i.e. questions to this post) indicate there is a power requirements developed for this technology. I suspect I will have to make some purchases to further my findings.

     

    (e) What is your testing procedure or project plan (Be as specific as you can)?

    1.Bench setup of PoE. Using a short commercial cable establish working unit and investigate power requirements.

              -sufficient power to operate Pi(s)

              - ability to communicate with Pi(s), using ssh on a network.

    2.Conform bench testing works with Pi(s) using local built cables.

              -test cables 568A & 568B

              -test cables maximum CAT5 length

    3.Integrate Pi with PoE into legacy network

              -establish requirements and understand limitations.

    4.Perform tests with Pi4 and Pi3B+

     

    Review Methodology

    This review summaries the details found in a series of blog posts created during the knowledge gathering process. If the truth be told, my RoadTest applications has always lacked a Yes response to the question regarding blogging in the E14 Community. I can now answer yes to the question, since I used the blog to document the findings during the process to develop this review.

    The Road to Raspberry Pi4B/ PoE Hat RoadTest Review (Introduction)

    The Road to Raspberry Pi4B/ PoE Hat RoadTest Review (Testing)

    The Road to Raspberry Pi4B/ PoE Hat RoadTest Review (cable in between)

    The Road to Raspberry Pi4B/ PoE Hat RoadTest Review (power supply)

    The Road to Raspberry Pi4B/ PoE Hat RoadTest Review (status-update)

    The Road to Raspberry Pi4B/ PoE Hat RoadTest Review (comparison Pi3B+)

    The Road to Raspberry Pi4B/ PoE Hat RoadTest Review (baseline Pi4B)

    The Road to Raspberry Pi4B/ PoE Hat RoadTest Review (Squirrel Moment)

    The Road to Raspberry Pi4B/ PoE Hat RoadTest Review (status:light at the end of the tunnel)

    The Road to Raspberry Pi4B/ PoE Hat RoadTest Review (PoE insight needed)

     

    Blog Review and Summary

    During this blog summary section I have peppered my commentary with three symbols , & . The first symbol is to indicate a testing value. The second symbol is to identify a feature I felt was a plus. The final symbol is to identify a feature that I feel a user needs to be aware of. It doesn't necessarily mean a negative but something to we aware of.

     

    (cable in between)

    A variety of 586A & 568B cables, commercially made and home rolled were used in support of testing the Pi & Hat combination. No issues were discovered. The Qualitative Test (documented later) cable was constructed from a box of industrial grade CAT6 buried cable. A few neighbours questioned why I had a cable wrapped around my house that terminated in a basement window. I needed 300 feet of space to stretch out the cable. Reminds me, I have to give that cable back to the local high school. I borrowed a box from them for testing.

     

    (power supply)

    My network does not have a network device (i.e. switch) capable of supporting a PoE devices. I purchased an external power supply to provide power to the PoE Hat and enable network communication. In addition the Pi4B supplied for testing, required an external power supply that I purchased.

     

    (status-update)

    It took considerable time to receive the required parts to conduct this RoadTest review due to shipping issues caused by the COVID-19 pandemic.

     

    (comparison Pi3B+)

    While waiting for parts to test the Pi4B, a Pi3B+ was employed to develop the CPU software load test. If a Pi has optional heat sinks installed (mine did) the PoE Hat installation will conflict.  PoE Hat will fit only if the Pi heat sinks are strategically placed. Using a local power to supply the Pi3B+ & PoE Hat combination, the supply voltage on GPIO pin 2, dropped from 5.11 to 4.78-4.83 when the CPU was software loaded. The PoE Hat fan engages when the CPU temperature reaches 50 degrees Celsius. Installing a PoE Hat consumes all the Pi GPIO pins. Testing is pending to determine if GPIO header extender will expose the GPIO pins for use. A Pi & PoE Hat combination doesn't fit into a standard Pi case. A Pi3B+ case was modified *badly) to fit the combo. No Pi4B cases on hand to perform a similar test.

     

    (baseline Pi4B)

    The Pi4B power supply arrived enabling some testing. A Pi4B network connection is labelled as unknown when identified by nmap.  Pi3B+ is identified as an Raspberry Pi. The local power supply voltage dropped from 5.23 to 5.17VDC when the CPU loading application was applied.

     

    (squirrel moment)

    During load testing development I was distracted by CPU throttling supported on the Pi's. CPU testing demonstrated the benefits of the fan that is provided by the PoE Hat and when and how CPU throttling is engaged.

     

    (PoE insights needed)

    Introduction of new technology has the potential to create issues that may need to be resolved. The Pi4B would not negotiate a 100M connection on my Netgear switch. An alternate D-Link switch worked. The same issue did not exist on the Pi3B+. Employing a PoE Hat results in 100M network connection. 1G connections are not supported.   Two pairs of the four pair cable are being used to provide power. 1G connections are not possible.

     

    Qualitative Test

    Compare the operation of a Pi powered using a local power supply verses the PoE Hat. To determine if the Pi was working and to establish communication an ssh session was established over a network.

     

    Operate a Raspberry Pi4B on the maximum length of home rolled (not commercially made) CAT5E (328 feet) cable while under a heavy load (high current draw). Complete a similar test on a Raspberry Pi3B+. Heavy loading is accomplished using software to maximize the cycles of the quad CPU's. Alternately heavy loading is created by using all GPIO outputs configured to sourcing current for a one blue LED attached to each. Measure the power on the Pi before and during the operation.

     

    Software Load Test
    Pi4B
    • Using a local power to supply the Pi4B & PoE Hat combination, the supply voltage on GPIO pin 2, dropped from 5.23 to 5.17 VDC, when under software loading.
    • Using PoE power to supply the Pi4B & PoE Hat combination with 325 feet of home rolled cable installed, the supply voltage on GPIO pin 2, remained at 5.07 VDC when under software loading.
    • Using PoE power to supply the Pi4B & PoE Hat combination with 100 feet feet of commercial manufactured cable installed, the supply voltage on GPIO pin 2, remained at 5.07 VDC  when under software loading.
    Pi3B+
    • Using a local power to supply (different than unit used in blog posting) the Pi3B+ & PoE Hat combination, the supply voltage on GPIO pin 2, dropped from 5.11 to 4.90 - 4.75 VDC,  when under software loading.
    • Using PoE power to supply the Pi3B+ & PoE Hat combination with 325 feet of home rolled cable installed, the supply voltage on GPIO pin 2, dropped from 5.07 to 5.05 VDC  when under software loading.
    • Using PoE power to supply the Pi3B+ & PoE Hat combination with 100 feet feet of commercial manufactured cable installed, the supply voltage on GPIO pin 2, dropped from 5.07 to 5.05 VDC  when under software loading.

     

    Pi3B+ or Pi4B & PoE combination supplied a 100M network connection as indicated on the D-Link switch.

     

    GPIO Load Testing

    OUTSTANDING: GPIO header extender on order. Will complete test when available.

     

    Conclusions

    This RoadTest review gave me the knowledge to consider purchasing a PoE Hat to power a Pi that did not have readily available power. The PoE Hat DC power delivered to the Pi's was stable under load and also when using a cable of considerable length. The cable requires no special care and can be constructed locally.

     

    Users deploying this technology need to be aware of some caveats that can impact installation and operation. External PoE power supplies add additional cost to installations. PoE supported devices have a reduced Ethernet connection speed. 100M connection speeds are the maximum.

    ********Update May 19,2020************

    Ethernet speeds related to PoE power supply and not a function of the PoE Hat.

    lui_gough commentary on May 10, 2020 identified a possible error in my determination of network speeds.

     

    A test of network conductivity with the Pi3B+ and Pi4B using a TP-Link Gigabit PoE Injector TL-POE150S supported the commentary. All Pi's connected at gigabit speed when the TL-POE150S power unit was inline (no power). Only 100M network conductivity was available with the L-COM PS4820-POE-1 power unit inline. Gigabit ethernet was supported when Pi's were powered from the TL-POE150S. Only 100M network conductivity when powered from the  L-COM PS4820-POE-1.

     

    The issue of the Pi4B & PoE Hat combo using the L-COM PS4820-POE-1 for power not being able to negotiate a 100M connection on the Netgear JGS524 switch did not occur with the TL-POE150S.

     

    Using TL-POE150S power to supply the Pi4B & PoE Hat combination with 325 feet of home rolled cable installed, the supply voltage on GPIO pin 2, remained at 5.07 VDC  when under software loading.

     

    These findings highlight an important understanding when considering deploying PoE. The Ethernet conductivity is a product of both the PoE Hat and what is used to provide power.

     

    Documentation for the PoE Hat is poor. It would benefit the user if the PoE Hat vendor provided some guidance on PoE power requirements in their documentation. The TL-POE150S unit specifies a compliance standard and the other two units did not. If the PoE Hat documentation had of contained this knowledge, the Ethernet speed conductivity issues would not have been present.

    *********************************************

    If you are considering using the technology, test legacy legacy network devices (i.e. switches) for supported speeds. Just because it indicates the speed is supported doesn't necessarily mean it will.

     

    Removing the network cable on a PoE device removes power. This is not natural in a network environment. Pi's can behave badly if power is removed unceremoniously. It is something to get use to when troubleshooting.

     

    The PoE Hat comes with a fan. The Pi gets to take advantage of this additional cooling.

     

    The Pi & PoE Hat combination requires a housing to support the increase in physical size. The standard Pi case doesn't contain sufficient space to house both units.

     

    Care must be taken when installing optional heat sinks on Pi components to avoid conflict with the PoE Hat.

     

    OUTSTANDING Without a Pi GPIO header extender the GPIO pins are not accessible. I hope to to have a further report on this when a component shipment arrives.

    OUTSTANDING: Social distancing protocols don't permit me access to the site for a production installation of the unit. I have a remote location in a building that has no ready available power. When permitted I plan on using this PoE Hat in that location.


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