Passive 24v PoE-5.5x2.5mm Barrel Adapter to Power PBA; Will it work?

My PBA is installed in a weatherproof comm enclosure below the Tempest. It is currently powered with only AA batteries. Inside the enclosure is a Ubiquiti ToughSwitch 5 that powers other stuff out there. There is also a TrippLite 2-port AC outlet inside providing power to the switch and a RPi PoE going to an adjacent enclosure.

The ToughSwitch can provide 24v@2A per port. I think it would work, but would there be any problems with using a COTS 24v Passive PoE adapter with a 5.5x2.5mm barrel connector on the other end to feed the PBA? The spec sheet for the PBA says “Any other 1A+, 6-24V power adapter”.

Due to limited space in the power enclosure, I cannot install a larger TrippLite, or even a multi-outlet adapter. I cannot run the RPi from the switch as it’s current draw exceeds the ports if I want it to run stable, due to the peripherals connected to and powered by the RPi.

This Splitter
This to convert the 5x5.21 on splitter to the PBA 5x5.25

The PASSIVE injector will not negotiate PoE with a switch port.

Although I am slightly hesitant to run a PBA on 24V, you may be able to get away with a barrel splitter on the Ubiquiti 24V/2.5A power supply to feed both switch and PBA if you are not pushing the PoE limits on the switch itself…

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OK, I will look into getting a barrel splitter. It will be trial and error to see if the combined load of the switch and PBA don’t drop the voltage enough to brown out the switch. Any reason why you don’t trust 24v directly to the PBA, even though it is listed in the specs? The passive 24 function of the switch doesn’t require or even support negotiation. It is a software switch that has to be manually enabled/disabled in the GUI. As for the load currently on the switch, one radio is using a max of 8/11.5W, and the other 7/11.5W.

Do you know the actual max draw in amps at 12 or 24v, or the watts of the PBA. Power budget per port is 11.5W or .5A@24V.

I manually charged one of the very early field test units. I thought I had a message somewhere documenting the current but I can’t find it. IIRC, it was less than 0.5A at ~3V so only 1.5W max. I doubt the losses in the PBA to step down the voltage are very high, so that might be a good estimate of max power draw.


I’ve heard reports over the years of some regulators in various electronic devices (not from WF) having poor voltage control with higher input voltages combined with amperage loads well below their maximum rating.

I don’t know what the over-voltage margin of error is for whatever power regulator or buck converter is being used in the PBA’s charge controller, so I personally would err on the side of caution and confirm that any external power source not greatly exceed the published 24V AC/DC spec when unloaded just to be safe…


Ok, that makes perfect sense, since it is at the edge of the max per spec sheet. Marking this response as the resolution, but will report back if I implement something that works before the post closes. Thanks for the response and insight.

Good to know, that means ~0.063A @ 24v. Should’nt be an issue at all.

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It would be nice if there was a POE TEMPEST that would link to the network directly!
The HUB could just communicate via wifi and reach the TEMPEST unit over UDP. This way no longer have to worry about lack of insolation, battery levels or signals whatsoever!

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There are several feature requests for an ethernet port on the hub. Just search for PoE in the Feature Request category to find them.

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Yes but what about the TEMPEST outdoor unit itself?
We already have 48V POE++ at the top of the tower for cameras. :wink:

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A PBA and an active PoE like this one should do the trick:


Yes it will work for power but I was referring to data as well so there would be a hardwired link from Tempest to hub.

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Hi @cpufrost ,
I am not sure if it helps but just in case it helps you. What I have done with one of my hubs that requires a better reception to my Sky (Early model Tempest) is to move my hub to up the pole. My hub is powered using a 5V buck converter powered via a 12v supply through an ethernet cable.
I understand that probably is not what you want because then the hub still requires its wifi to get down from the tower. And the 2.4Ghz wifi will likely be more difficult to get down to your router than the 915Mhz between the Tempest and hub. Unless perhaps you also place a wifi extender connected to your ethernet up the tower to then bring the signal down using the ethernet? Just offering options.
cheers Ian :slight_smile: