I am new at working with Power over Ethernet.  Is there an easy way to provide PoE to a Ubiquiti router from a standard 12VDC power source?  I know I could use a 12VDC to 120VAC inverter but these are typically in short supply and a bit expensive.  Ideally I'd like to somehow be able to power a Ubiquiti router from PowerPoles.

Thanks to those who ported the BBHN firmware to the Ubiquiti hardware.  I now have a Bullet and AirGrid both running BBHN and I really like the devices.

73,

Harry Bloomberg W3YJ

hbloomb@gmail.com

So I have not seen an official spec, but Mirocom sales site and some other reports I have seen seem to suggest 10vdc is OK to run these on so that means a 12v battery charge/discharge range is in the avaliable power range.

What you want is a PASSIVE POE INJECTOR with pins 4/5 as Positive and 7/8 as NEGATIVE  pins.

If this is a field setup you can probably get away with the really simple one such as follows: (I found it more expensive to try and make one so I didn't bother and went straight to buying though i haven't used any of these below yet) (Hint: just cut the ends and put Anderson on them)

http://www.amazon.com/HCP05-Passive-Injector-Splitter-Connector/dp/B00DZLSRJC/ref=sr_1_1?s=electronics&ie=UTF8&qid=1393814600&sr=1-1&keywords=passive+poe+injector

http://www.amazon.com/Passive-injector-Power-over-Ethernet/dp/B00EBCGJVW/ref=sr_1_4?s=electronics&ie=UTF8&qid=1393814600&sr=1-4&keywords=passive+poe+injector

(NOTE: always verify the pins before connecting an unknown POE injector to your device to avoid destroying it)

If you need to power several (such as I need to for the programming lab)  I have actually used:

http://www.amazon.com/WS-POE-8-ENC-Multi-Passive-Injector-devices/dp/B0075F7F2O/ref=sr_1_3?s=electronics&ie=UTF8&qid=1393814600&sr=1-3&keywords=passive+poe+injector

(at any given time 4+ have been plugged in and active in my lab off my central 13.8 supply)

If these will be outdoor permanent installs, especially if you get lighting,  I recommend something a bit more protective however with built in lighting protection such as:

http://www.l-com.com/power-over-ethernet-single-port-cat5-passive-poe-midspan-injector-w-integral-lightning-protection

If you will be trying to run these in a car with a motor, I don't know how well the on board SMPS handles up and downs. A capacitor on the power lines may not be a bad thing in a car deployment. I have  planned to be preemptive and instead install as 12v to 16v dc-dc switcher to bring the voltage up and clean it up for car usage but I have been known to over engineer.

I also plan on using the dc switcher to allow me to dump a battery at the bottom of a hill and run up to 300ft of CAT5 up to the top of a hill (Higher voltage, less current less system losses.) This also applies if you have a long run from your power source to your Ubiquiti device.

Useful calculator for POE voltage drop: http://blog.fosketts.net/toolbox/power-ethernet-calculator/

This device looks like it ought to help me make sure the right voltages are getting to the right pins:

http://www.amazon.com/dp/B00B9GFJAU/ref=pe_385040_30332200_pe_309540_26725410_item

73,

Harry Bloomberg W3YJ