UCTRONICS PoE HAT for Raspberry Pi 4, Mini Power Over Ethernet Expansion Board for Raspberry Pi 4 B 3 B+, with Cooling Fan

Product Information

As PoE power comes from a central and universally compatible source, you can manage power to devices from a centralized switch. I don't know what the limits are on the USB current, but would guess 5.08V x 0.46A = 2.3368W is too much against 4.97V x 0.37A = 1.8389W. Perhaps 2W is where the limit is ? Dominic 3:09: It does it by — first of all, it looks for some capacitance on the cable to know that there is something there. And then —

Eben 3:45: And there are PoE modes where you put the power on the spare pairs that are spare in some standards. In March 2018 we announced the launch of Raspberry Pi 3 Model B+. One of the many features added to the new board was the ability to be powered through Power over Ethernet (PoE) with a HAT. We are really pleased to announce that the PoE HAT is on sale from today.It would seem that I've managed to kill two Raspberry Pi 4's in a short period of time. I was trying to set one up as an internet gateway powering it with a PoE HAT from Waveshare. Designed to be stylish and functional, the PoE HAT+ Case features side and top 'hex' ventilation for the PoE+ HAT fan to keep your Raspberry Pi nice and cool, and enables access to all the Raspberry Pi Ports whilst keeping both boards safe and sound! This outputs the current in microamps, meaning at the time of the reading, the PoE+ HAT was supplying 0.6A to the Pi (0.6A at 5V is 3W).

Despite the PoE HAT’s ability to supply up to 2.5A, the experiments we ran in response to the reports suggested that, when it was used to supply some boards, the USB supply would trip out at a much lower current. Mice and keyboards worked fine, but higher-current devices such as wireless dongles and hard disks would fail. The cooling fan is temperature-controlled, which starts to spin (at a slow speed initially) at 40 degrees. The fan then speeds up as the temperature increases (around every additional 5 degrees) ensuring cool and quiet operation. So, might not be a new issue, just a reoccurence of an old one. It may not be related to the PoE HAT, just that adding one is making the issue appear in these two cases.

Features

You can use it to power your Raspberry Pi via Ethernet cable if you have a PoE capable switch or router (or a PoE injector) installed on your network. The PoE+ HAT also has a built in fan to keep your Pi's processor super cool and running efficiently. There are definitely similar teething problems with this next-gen PoE+ HAT, and hopefully QA for the next board's launch is better. Unlike other RPI, on a RPI4 the power LED is fully under the control of a GPIO expander, and when booting Raspbian resets this IO expander so causing the PWR LED to blink off on reboot. On booting the bootloader enables it again. But if the PWR LED goes off (blinks) at any other time it means have an unfit power supply/power cable. in short, the PWR LED should be always on except for a very short time just before a reboot happens. The USB ports on the Pis only supply 1.2 amps. This is annoying, but isn’t a weakness of the PoE HAT at all. We can hope for a future Pi revision that raises that limit. Until then, the workaround of tapping power directly from the 5v rail works nicely.

In 2018, the Pi Foundation introduced the PoE HAT for the Pi 3 B+. That initial version had a fatal flaw: on many Pi boards, it could only supply about 200 milliwatts of power to USB before the current limiter reset. Martin Rowan first documented how plugging in almost anything besides a keyboard and mouse would trigger the Pi's overcurrent protection. Dominic 9:34: Yes, but we needed the area. If you have a look at it, it is quite a dense board. But because we’ve been able to simplify some of the electronics now and integrate things more, especially around the area of the transformer, we’ve got this L-shaped board. And that then allows us to put it in the new Pi 5 case as well. When getting PoE devices, be sure to take note of their PoE type as their power budget per device are different. PoE devices supply power according to the device IEEE 802.3 generation where the life-cycle generation is indicated by the extension: “af,” “at” or PoE+, and “bt” or “UPoE”. Here is the following power budget per device for each PoE type:

Dominic 1:39: Aha! That takes the volts from the PoE — from your Ethernet cable, so it’s around 48V, and brings it out to those pins there then for the PoE HAT to take that, and convert it to the 5V, right?

Furthermore, PoE can be easily moved around and reconnected. It is like plug and play where an entire network doesn’t have to be dismantled if you wish to move it around. Devices like SSDs consume around 3W, and two of them together would be 6W. According to the Pi documentation the Pi 4 itself, minus the USB usage, should have 9W available to it for stable operation.

New PoE++ HAT Differences

Take care when separating the HAT from the Pi.Pull evenly so that it detaches from all the pins at the same rate; do not pull one end of the connector off before the other!