Review on 🔌 UCTRONICS PoE HAT for Raspberry Pi 4: Power Over Ethernet Expansion Board with Cooling Fan by Matt Dyen

The specifications for this device allow 3 amps at 5 volts or 2 amps at 12 volts and some combinations up to 25 watts. So I charged it at 22 watts: 2 amps at 5 volts and 1 amp at 12 volts. The device then drew 29W from the 802.3at switch. That is more than the permitted 25.5 watts. The device used 29 watts to produce 22. I also tested it with a 5 volt, 3 amp load - it took 21 watts to get 15 watts. The ripple at 1 amp and 12 volts was over 1 volt ripple. Those 6 and 7 watts are warm. The device gets very hot. The attached photo shows a Schottky diode operating at 100 degrees C - the boiling point of water - with a 5V 3A test. The device is a two stage converter, it converts 802.3at to 12 volts and then from 12 volts to 5 volts. Volt. This means that the conversion loss is twice as high compared to two independent converters. The ripple is also very high. Each converter saturates about 4 watts, so use less than 8 watts total and you'll be fine. More than 4W at the 5V output will cause rapid heating. The device is isolated and the fan is a bit noisy - it works even when the Pi has no real work to do.