How would you power PoE devices on a 24v DC system?

General Discussions
1

I’m looking for some advice or alternatives if my thinking is flawed.

We have a motorised gate serving 25 properties, powered by a 2.5 kWh 24v LFP battery, connected to a MPPT and 600W PV which is the only charging source, no AC, the site is off-rid.

We want to install a LPR camera at the gate, plus a Ubiquity Litebeam dish to connect it to the network, both these devices can be powered by PoE.

Here’s where it gets interesting, the LPR camera requires 48v PoE and the Ubiquity Litebeam requires 24v PoE.

So my thinking is, I need a PoE switch which can power both 24v and 48v devices and it must be powered by 12 or 24v DC, then I can chuck its AC power brick and connect it directly to the battery?

Will this work, any alternative, more efficient ideas?

2

Yes you can if it has a DC plug (and isn’t remote and powered by PoE)
The cameras will need a DC-DC converter. How many cameras are there??

3

I bought this TP-Link switch recently. It has a DC barrel jack on the back, can take up to 53V, and of course it ships with a PSU that you plug into AC.

The tricky bit will be to make 48V from your 24V. Of course the easy way is to use a Victron 24/48 DC/DC converter. But there might be other similar boost converter solutions.

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4

The correct POE switch will do the voltage switching for you. Its a backwards compatible technology with active POE. Buy a decent Mikrotik.

5

or use a 48v to 24v poe converter. I use these for my older ubiquity wifi access points: 48V to 24V POE Converter 24V 24W POE Splitter for 24V Passive POE MikroTik Accessories Gigabit 802.3af POE to 24V Passive ModeB - AliExpress 30

For 12v, you get the same. You also get PoE splitters, which splits out the power from the network cable to a barrel plug for cameras that doesn’t support PoE. These can do 12v or 5v and you even get ones that split it out as usb-a/b/c to power items that doesn’t support poe. Great to have lots of things running off the PoE switch.

And yes, I do have a mikrotik, but I wanted to be safe that I only get the power out I need.

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6

I have this converter: https://www.meanwell-web.com/en-gb/dc-dc-enclosed-converter-input-19-36vdc-output-sd--200b--48
At a very reasonable price

7

Yes, I forgot to mention that part, as part of the original plan, I want to use a Orion 24/48

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8

Something like this should work.

9

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If you have the power supply and only a few cameras this is all you need.