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Power requirements for DPQ3925-x cable modem wireless router

Unanswered Question
Feb 8th, 2014
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Dumb question... is it ok & safe to run a DPQ3925-x on 12V?


Background...


We get a lot of power outages. For various reasons, my network is configured as:


Cable -->

  • DPQ3925-x
    • Netgear router
      • network 1
    • D-Link router
      • network 2
    • Optus HomeZone pico cell



Power outages are usually at night, and power can come on at any time. Everything starts at once. The DPQ is a bit slow to boot, so almost everything else beats it up (except for the HomeZone which takes nearly 20 minutes to restart). Numerous devices on the network don't get a proper network connection, and need to be rebooted later before they work. This may be a DHCP issue, or something to do with DNS, I don't really care what why. It's very tedious!


I've installed a 12V DC power supply with battery backup. It powers the DPQ, the Netgear router and the HomeZone. Together they pull a hair over 2 amps, So, in theory with a 7.4Ah battery I should be able to ride through a 3 hour outage without losing wireless network or 3G (through the HomeZone). I won't have to wait the 20 minutes after power on to use the phone. I want a DC UPS, rather than AC, because I can't see the point in wasting energy bouncing the power up and down 240V -> 12V -> 240V -> 12V with all the inevitable losses and heat production.


It was only when installing the power supply that I realised the DPQ says it wants 15V, not 12V. I tried powering it up on 12V, and it appears to work normally. I notice that some models of DPQ3925 have their own battery backup. Perhaps the 15V supply is necessary to be able to recharge internal 12V batteries, and the -x model (with no provision for battery) just uses the same PSU?


If necessary I can add a 12V -> 15V step up regulator into the UPS, but that's extra expense, heat and complexity, which I'd rather avoid.


So, can anyone tell me if there are any disaster scenarios which may result from continuing to power the DPQ on 12V? 


Thanks!

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