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Battery Power options

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Battery Power options

I am new to this and currently just have my stuff plugged into AC in my house. My setup in my home will be 2 x Ubiquity NSM2 , 1 ip phone POE, and a 5 port POE switch that everything will be plugged into.  I need to keep all this small and light for various reasons and I only want a couple of hours of run time right now.  I am considering just buying a computer UPS. 

K5DLQ's picture
I use:

I use:
12VDC sealed battery (7Ah)
passive 12VDC power injector to the node
12V to a network switch
my VOIP phone is a grandstream GXP2000 which requires 5V, so I wired a cheap USB car charger to the 12V battery and plug the VOIP phone into it.


thx for the quick reply ,

thx for the quick reply ,  does the POE injector run on 12 V ?  How do you hack the POE injector to use the battery ?

K5DLQ's picture
POE Injector is passive.  It
POE Injector is passive.  It will pass whatever you feed it.
I created a cable that is PowerPoles on one end and DC coaxial power plug on the other.
ok my POE injectors are the

ok my POE injectors are the ones that came with the nanostations. They are just one piece , an AC plug goes in one end and POE go out the other so there is no round DC power plug. 

k0tan's picture
12v Injector
That's a great looking inexpensive injector.  The GXP-2000 do PoE, but I read they want 48vdc. Do you think this injector would do the trick for them?
k1ky's picture
Battery Power options
A UPS with an external  (big) battery is a good option as you can run additional equipment, like a laptop or something.  The Nanostations need I believe a minimum of 10.5 Volts AT THE NODE to operate. This doesn't leave much room for voltage drop in cable runs if you use 12 volts.   Standard UBNT POE Injectors supply 24 volts DC..  There is a screw under the Ubiquiti label that holds the clamshell together.

Don't forget to fuse your DC line if you elect to provide external power.
Not all Ubiquiti supplies are
Not all Ubiquiti supplies are 24v.  16v is a very common model and is actually preferred for short runs as the 24v model is VERY close to the zener voltage and really is only intended for long runs.

A SD-15A-24  DC to DC supply paired with the passive injector solves the issue of long run injection from a 12vdc source. I recommend to dial it down to 22vdc.

It also adds some isolation to the circuit which isn't a big deal on a portable setup but for those you mounting at a tower site it can reduce ground loops. (The shield of these radios are tied to DC ground)

I recommend  against a  UPS's.  Some refuse to start when no AC power is present, they generally have inneficent inverters, and are not generally intended to be used frequently.
M1BKF's picture
POE cable

I made a cable with a RJ45 on one end and a car lighter plug on the other for running a PicoStation portable. Works ok; about 20ft flexible network cable. 

that's cool , do you happen

that's cool , do you happen to know which wires in the ethernet cable are supposed to go with + or -  dc connector ?

M1BKF's picture
POE cable pins

The ground, -ve, socket sides, goes to RJ45 pins 7 and 8, +12V, socket tip, goes to RJ45 pins 4 and 5.

K5DLQ's picture
take a look at the photo from
ok I thought that was what

ok I thought that was what you were talking about but I do not have that.  I don't know if I got something weird or not but I ordered my Nanostations off Amazon and they came with a POE brick that is not like the one in the picture. The ones I have do not have the round dc plug, there is no separate  wall wart, its an all in one thing.  AC cord goes in one side and that's the only power inlet. 

this is not the exact thing but its the same type

K5DLQ's picture
Correct.  If you want to use
Correct.  If you want to use AC power, use the supplied 120VAC -> 24VDC Ubiquiti PoE adapter.
If you want to use 12VDC (or 24VDC if you have it) power, use something like the passive injector that I previously posted.
cool I will just get one of

cool I will just get one of those.  Is there any advantage to 24V over 12V or does it all work ok ?  These are Nanostation M2's.  

K5DLQ's picture
12VDC works fine for short
12VDC works fine for short cable runs.
The min voltage is around 10.5VDC for a device.  You can calculate the voltage drop based on length of cable.
WU2S's picture
PoE power calculators
You can get some assistance for this from POE-Texas or Active Vision with their online PoE calculators.
W6RUF's picture
Reality Check
I've been following this thread closely because we are deploying mobile mesh nodes.  Power conversion from 12VDC to the 18 or 24V using a boost power supply introduces conversion inefficiencies so going to straight 12VDC is very attractive.  
Assuming we use Outdoor Carrier Class Shielded Ethernet Cable with a typical M2 or M5 Nanobridge, here is what Ive calculated.  Sounds like a typical mobile node deployment with 35 feet of POE cable is no problem.  What do you think?
Image Attachments: 
WU2S's picture
Re: Reality Check
You will want to make sure that the Ubiquiti product gets at least 10.8 volts at its Ethernet connector. The datasheets for the Nanostations (M2, M3, M5) say that the maximum power consumption is 8 watts. The Rocket (M2,M3, M900) is 6.5 watts and the Rocket (M5) is 8 watts. So you might want to increase the supply voltage to 15 volts with suitable current to power your devices on a long cable run.
WL7COO's picture
Hello Emmanuel; I've been running one, two or three Ubiquities

from the AUX Power system in the MESHMobile van through a 400 watt inverter.     As inefficient as this is,  just from the normal system charging when the engine is on, the isolated 95 AH Auxiliary battery has supplied adequate voltage to run a pair of Rockets through a 400 watt inverter with the standard Ubiquity POE injectors  for 7 hours plus before dropping the system voltage from approx 14.3 v to  between 12.4 & 12.3 v.   At that time I start the van and set the high idle control so the 250 Amp Alternator is outputting 14.4 volts or more - usually between 1300 and 1400 rpm.  This recharges the Aux battery to almost 14 V in maybe 20 minutes burning about .3 to .4 of a gallon of diesel.   Subsequent run periods are a little less but stlll  more than 7 hours.   For RF Sniffing purposes I just plug  a 75 watt or the 400 watt inverter into one of the Aux system power points and never see the voltage of the Aux battery get below 13 volts.  I usually use a 60' Ubiquiti Carrier Grade Cable to permit maximum flexibility in placing the radio on  up to 40' a mast near the  van or 8' or 12' above the top of the van.  Mobile 'sniffing' can be done with an NSM mounted inside one of the windows in one of the window/wall mounts. This requires a second person to monitor laptop. 

On both the drawing board and in my parts piles are sufficient small scale solar  systems ( 100 watt, 30 watt and a pair of 10 watt "solar Wings") to run several radios indefinitely either off of the Van's Aux battery, a 24 to 36 lead acid equivalent Deltran LifePo4 battery or one or two of the 9 AH SLAs.  

Be conscious of the fact that LifePo4 charging protocols work safely with non LifePo4 batteries but not vice versa.

The minimum of 10.4 V  *at the radio*  seems to be gospel.  I haven't run any batteries down that much yet but it is repeated by Ubiquiti and everyone with more real world experience and engineering chops than I'll ever have often enough that  I feel safe using 10.4 v as a planning minimum and much more comfortable using Randy's suggested 10.8v minimum.  I just have to wean myself down from my 12 v comfort level <g>.

You are on the right track, keep trying different things and share what works well for you.

BTW Kudos for the robust connectivity you recently installed at your QTH.  The more routes that are established between the Sierra foothills and Mt. Oso in Central CA,  the better.

My best performing AREDN radio is one I set up as weekend test deployment of a Mobile Portable concept May 14, 2016.   It worked so well the test is still ongoing almost a year later<g>.

73, ...dan wl7coo   

wa2ise's picture
Something like this http:/
Something like this may work for you.  I've been using a similar 12Vin/out UPS device to keep a small OpenWRT router I'm using as a web page server in its RAM. 
KD2BKD's picture
7800mah mini dc power bank
Here is a 7800mah uninterrupted power bank with several different voltage outputs including 15v/24v at 1A.  Also has 5v/9v/12v at 2A including USB power.

Comes with a wall wart and may be a good inexpensive solution for smaller setups.
Speaking of lithium...
Speaking of lithium...
During field day I ran my nodes off of 3S3P Li-ion battery packs, made with 2200mAh 18650 cells salvaged from old laptop battery packs. Compact, light weight, excellent run time, and very easy to attach to a pole with just a couple zipties. 

A while back I did some quick current measurements at different voltages on a Nanostation M2:
Voltage Av. Current (A) Av. Power (W)
12 0.21 2.52
11 0.23 2.53
10 0.25 2.5
9 0.27 2.43
8 0.3 2.4
7 0.33 2.31
6 0.38 2.28
5 0.45 2.25
Cutoff 4.3V    
So if looking for a turn-key
So if looking for a turn-key battery solution, I recommend a 4S protected Li-po or Li-ion, with proper charger of course. This will provide a max voltage of 16.8V when fully charged, and minimum cutoff voltage around 12V. Using the table above, ~200mA current at 12V...... a 5000 mAh 4S battery should be good for about 25hrs of runtime.
Hobby lithium batteries are very affordable, just need to build an adapter into RJ-45 

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