Elk M1 Power Question - modem/router/xep

jon102034050

Active Member
Hey all, I've got a pretty standard Elk M1 Gold setup, nothing too fancy with 4 motions, 6 doors, 4 speakers, and 2 keypads all wired.  I'm using AlarmRelay for internet monitoring, and all is going well so far, but I need to address the issue of battery backup on my network components (router, modem, m1xep).
 
I found the following thread after searching:
 
http://cocoontech.com/forums/topic/22538-elk-m1-motion-sensor-low-voltage/
 
But it doesn't quite fit my situation.  The router, modem, and m1xep are all 12v, and use 600mA, 750mA, 300mA respectively.  But I've also got a Commscope amplifier that is amplifying the cable feed that is plugged into the wall and is 15v using 500mA.  As I understand it, I'm unable to use the p212s now because that doesn't run at 12v  (also it consumes more than 2 amps...)
 
How are others addressing this?  I'm still pretty new to this stuff, so any and all advice is welcome!  Thanks!
 
Also, I did some testing both with and without the amplifier on my cable feed, and I consistently got 8-12mbps faster with my wired internet connection (using the amplifier), so I think the powered amplifier is a necessity.
 

RAL

Senior Member
I think some folks would solve this by plugging the wall warts for the various components into an off the shelf 120VAC UPS.  The pros here would probably frown on that appoach.  It's also not the best way to solve the problem in terms of efficiency, since it will be taking 12VDC from the battery, converting it to 120VAC, and then the wall warts will be converting it back to 12VDC.
 
A better solution would be to get an auxiliary 12VDC power supply from Altronix.  That will be able to provide the power directly that you need for the router, modem and XEP.  For the amplifier, you could use a step-up DC-DC voltage converter to boost the 12VDC to 15VDC.
 
I haven't used this particular step-up converter before, but it is designed around some pretty standard parts and should do the job nicely.
 
http://www.ebay.com/itm/DC-DC-Converter-Regulator-Step-up-Step-down-2-in-1-/370538642812
 
For the 12VDC power supply, something like an Altronix AL400ULPD4 or PD8 should be adequate.  If you are patient, you can often find one on eBay for $50 or so.  A couple of 9aH batteries should be able to run things for about 8 hours, possibly more if actual loads are lower than the numbers you quoted.
 

jon102034050

Active Member
RAL said:
I think some folks would solve this by plugging the wall warts for the various components into an off the shelf 120VAC UPS.  The pros here would probably frown on that appoach.  It's also not the best way to solve the problem in terms of efficiency, since it will be taking 12VDC from the battery, converting it to 120VAC, and then the wall warts will be converting it back to 12VDC.
 
A better solution would be to get an auxiliary 12VDC power supply from Altronix.  That will be able to provide the power directly that you need for the router, modem and XEP.  For the amplifier, you could use a step-up DC-DC voltage converter to boost the 12VDC to 15VDC.
 
I haven't used this particular step-up converter before, but it is designed around some pretty standard parts and should do the job nicely.
 
http://www.ebay.com/itm/DC-DC-Converter-Regulator-Step-up-Step-down-2-in-1-/370538642812
 
For the 12VDC power supply, something like an Altronix AL400ULPD4 or PD8 should be adequate.  If you are patient, you can often find one on eBay for $50 or so.  A couple of 9aH batteries should be able to run things for about 8 hours, possibly more if actual loads are lower than the numbers you quoted.
 
Sweet, this helps, thanks!  I like the idea of getting rid of the wall warts, which is why I was kind of wanting to avoid the off-the-shelf ups route.  I just got off chat with comcast, and they said that they'd replace my 15v amplifier with a 12v one for no cost if I just dropped by their store.  Seems like this would be a little cleaner than having to deal with a step-up converter.  In the meantime, I'll checkout that Altronix unit you mentioned.  It's too bad Elk doesn't have a 4amp monitored power supply...
 

RAL

Senior Member
If you can trade the amplifier for a unit that runs on 12VDC, that's definitely the way to go.  Eliminating the step-up converter leaves you with one less thing to go wrong.
 
The Altronix power supply has contact outputs that indicate AC power loss and low battery conditions, so you can wire those up to zone inputs on the M1 to provide supervision. 
 
You might also want to add an Altronix LPD low battery cutoff that will disconnect the batteries if they discharge to a voltage below 10.5V.
 

jon102034050

Active Member
Well, to make things even simpler, Comcast came out, tested the lines, and said I don't even need the amplifier!  Thanks for the help RAL!
 
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