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AirRouter AR (and HP) DC Power options

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k1ky's picture
AirRouter AR (and HP) DC Power options
I have evaluated the AirRouter AR DC power requirements finding that it consumes about .48A at 5 volts.  I haven't yet analyzed what it will do if I lower the power.  I know that changing the power levels on a Linksys WRT54G didn't seem to make much difference.

My question is if anyone has attempted to see if the AirRouter AR can accept power and run from being injected into the USB port?

Same question would go for the AirRouter HP if it works on the AR.  Usually everything internal to these units (and the Nanostations) actually "run" on 3.3 volts internally.

kg9dw's picture
I haven't tried that....but
I haven't tried that....but if you look back through the ubiquiti forums from 5+ years ago you can see some of the thoughts of using the USB port for other things, including powering some air grids. 
k1ky's picture
The results are in....!!!
Well, almost.  I have successfully powered, upgraded to AREDN and have now operated an AirRouter AR with 5 volts supplied through the USB Port for almost 4 hours so far off of a cellphone backup battery pack.  It's hovering around .48 amps at 5.16 volts.  I'll do more analysis after varying power levels (which I doubt will make much difference, but I can only hope).  My experiments with the Linksys WRT series long ago didn't change power usage with output power changes.

It connects and operates normally on my MESH network.  I'll be installing the chat modules and will make some postings there soon.

I did also fire up an already programmed AirRouter HP through the USB port earlier, it lit up, but I wasn't able to successfully connect to the Lan port (tried 1,2 &3). Inconclusive at this point on that model.  I did not check whether it connected to my MESH system.

I haven't tried any external splitters, but they should work as well - and some of them can accept external power to handle the extra load of the devices that are attached to them - just don't know if they will "feed" power back to the host device.  Much more testing to come!

k1ky's picture
AirRouter HP no go on 5 volts through USB connector
The AirRouter HP lights up but the ethernet cable connection (Ports 1-4) won't connect to the browser/computer - thinks it is changing.  Don't think I could see it on the MESH system either.  Lights up, draws .48 amps @ 5.16 volts but nobody is home.  I'll hook it up to my variable power supply through the POE port later today and see how low it will go.

In the end I would never
In the end I would never recommend backfeeding power through the USB port, there are talks on some experimental type devices that handle it and some less then experimental devices (PI's -- but even they don't recommend it) and sometimes some other hobby type gear that does it but in general commercial type gear doesn't come designed to backfeed power. 

It is actually a USB Spec violation to backfeed power as power is suppose to feed from the host device (Airrouter in this case) only.

The fact that nothing world would make sense depending upon circuit layout its very possible the USB input is not connected to all Circuits. I

It looks like in Argentia they ship a 24v POE injector,  I forget what the last ones here in the USA have been.

In any case that could mean that inside the units multiple voltage rails are separated off the central input supply.

Probably best to just feed these devices how the manufacture intended and at the voltage the manufacture intended. For EMCOMM we will want these units to work flawlessly during a disaster, nothing worse than getting into the field and finding a failure.
N8NQH's picture
Info here for the HP model
K6AH's picture
Vdc over a distance
If you are running the power over any distance, you should use both pairs... as follows:
  • Pins 4 & 5 (blu/wht & wht/blu) are the positive power pairs.
  • Pins 7 & 8 (wht/brn & brn/wht) are the negative power pairs

Andre, K6AH
N8NQH's picture
yep; Conrad also pointed that
yep; Conrad also pointed that out.  At the bottom of the web page:

Note: thanks to CL's mentioning... I should have included that the POE actually uses 4 pins for power to the node, both 4 & 5 for the positive, and both 7 & 8 for the negative. The above homemade adapter is only 3 inches long. With this short of length, there's no concern with voltage loss when just using two pins total. If you go much longer, it's better to run all 4 paths.

12v power

If you have a few skills with an iron you can power the air router up by adding power to the unit before the voltage regulator that the POE feeds I run mine off 12v from the car directly with no problem. just don't forget the 1a fuse its not hard to add in and the connectors are not super small. I will Attach Some Photos To Aid In the Mod. I will Also Add A Photo Of How to Add Poe To yor DtD Port Also Just Rember That If You Do this mod that it also adds power to the WAN port also if people have other ideas i am open to the possibilities of inproveing this setup but so far this is the best i have come up with without reinventing the whole thing and to top this off it still fits inside the case just drill a hole whare you want the dc plug to be and you are done. I put my dc plug next to the wan port.

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