Raspberry Pi 4 + POE+ Hat keeps rebooting

Just setting up my Raspberry Pi 4 w/ POE+ Hat with a USW-Flex powered by 60W POE Unifi injector.
Boots fine, but as soon as I plug in the USB dongle for the ADS-B Receiver it reboots, and keeps rebooting. Seems like a power issue. If I have a POE+ Switch, a POE+ HAT should that not be sufficient to run a RP4 w/ ADS-B Receiver?

What is the power usage in the UniFi gui? Before and after you plugin the USB dongle?

What are the specs of the POE hat? The original powersupply for a Pi4 is 3amps.

So with the dongle it is about 7.79W. Looks like I overlooked setting the POE injector as the power source… Which is a bit bonkers because it was working sans-usb… Looks like it is working now… Thx…

Looks like while it is working, the range is much smaller. Going to try using a POE → USB-C adapter to see if that works any better…

In case a reference helps. I use a Pi 4 w/ POE+ Hat: Airspy R2 with bias tee enabled + RTL-SDR LNA + USB bias tee + Active Diapason Antenna and Orange FA pro stick + Uputronics 978 LNA via USB. This powered by Ethernet/POE from a Unifi POE switch. (USW-Flex switch used at the moment).

The above works fine. Wattage usually around 11 watts but fluctuates up to around 13 watts. The only difference with POE+ Hat vs the old POE hat is slightly higher watts used by the POE+ device. And Pi 4 reported voltage, with all the listed devices connected, always stays at 0.8500V with the POE+ Hat compared to always around 0.8700V with the old POE hat.


I have another Pi 4 with POE+ hat with an Airspy R2 bias tee enabled powering an amazing LNAU-0122-648, VHF Aviation Band Preamplifier (LNA) and Filter at the antenna. The Pi 4 is overclocked to 1750 for optimal rtl_airband peformance. This setup pulls 9 - 10 watts from a switch. Only powering the Airspy+bias. Voltage would be lower than the Pi referenced above if it wasn’t overclocked with over_voltage=2.


Dang, that is helpful. I am hoping I can get this dialed in soon…

I can add the only difference is my USW-Flex is powered by Switch Enterprise 8 PoE instead of an injector. I’ve powered the POE+ Hat directly from the Switch Enterprise as well, but it makes no difference since the total power consumption is under 15 watts. So POE vs POE+ source don’t matter unless you approach 15 watts!

Nice Pi stats, which tool you are using?

RPIMonitor, see this thread. It’s a bit slow and manual to setup at first but works well for all Pi projects. There are a few helpful preconfigured settings in that thread.

1 Like

This topic was automatically closed 365 days after the last reply. New replies are no longer allowed.