Low power/low voltage computers and network equipment that can be run from 12v batteries

westyd1982
westyd1982 Solar Expert Posts: 85 ✭✭
in Energy Use & Conservation #1
I'm curious if other people have had success running various computers and networking equipment from 12 volt battery systems. I have two small linux boxes and some networking equipment that I run directly from my 12v batteries. The following are what have worked for me so far:

Sheevaplug - 24/7 server to monitor my powersystems and a weather station. Also serves as a web server. I had to replace the AC power supply with a DC power supply that provides 5v to the main board. This is a great linux server and it only draws about 0.25A at 13V.

Seagate Dockstar - 24/7 server with a 1 TB hard drive that provides backup and internal network services (family calendar server). This has a built-in DC power supply and runs directly from our 12v battery bank. Also only draws about 0.25A at 13V.

Linksys 8-port router (BEFSR81)- Used to be the household router, but now just operates as an 8-port switch. This has a built-in DC power supply and runs directly from our 12v battery bank.

Linksys 4-port wireless-N router (WRT-160NL) - Used to be the main household router and main wireless access point, but now just operates as a wireless access point for our downstairs area. This has a built-in DC power supply and runs directly from our 12v battery bank.

For efficience, I prefer powering these devices directly from the 12v batteries instead of DC->inverter AC->DC. It is also very reliable in that I always have DC power.

Has anyone tried wiring a newer Apple Airport directly to a 12v battery? Can it handle input voltages from 11.5-15 volts? I'm currently running mine from inverter AC, but would like to build a cable to run it directly from my 12v battery bank if possible.
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #2
    Re: Low power/low voltage computers and network equipment that can be run from 12v batte
    westyd1982 wrote: »
    ...Seagate Dockstar - 24/7 server with a 1 TB hard drive that provides backup and internal network services (family calendar server). This has a built-in DC power supply and runs directly from our 12v battery bank. Also only draws about 0.25A at 13V....

    That's pretty hard to imagine as the hard drive is likely to require more power to run by it's self, is this a flash drive?

    I have a few small appliance computers (7"x7") that run on 13 volt 5Amp adapters from my house current, they use about 7-10 watts in general according to a Kill-A-Watt meter I've run them on a 2Amp adapter just to see how they do, and I didn't have problems with WD scorpion(?) laptop drives installed, but even going to a laptop drive that draws .75 amp (seagate freeplay 1TB) created problems.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • RandomJoe
    RandomJoe Solar Expert Posts: 472 ✭✭✭
    #3
    Re: Low power/low voltage computers and network equipment that can be run from 12v batte

    I ran my core network directly off 12V back when I was using a 12V main bank. Had two different cablemodems - first was Linksys, second Scientific Atlanta when the cableco obsoleted the Linksys. Both came with 12V wall-warts, and ran fine straight off the batteries. Had a WRT54G for wireless, and - hm, can't remember the switch I used in addition - both again used 12V wall-warts. Firewall machine was a 7W ARM SBC that again used 12V input. Also had an Atom-based "carputer" with a power supply specifically designed for car use (something like 8-20V input) so it was fine.

    Of course all this stuff had been around a long time, and was cheap enough I wasn't too concerned with trying it out directly on battery. I never equalized with this stuff connected either.

    I've since gone 48V battery bank, so just run everything off the AC inverter, but occasionally give thought to what I'd have to do to run off a 12V battery in a pinch. A fair bit of the low-power devices I use are now 5V input, but I now have an easy way around that should I need to. Recently started tinkering a lot with Arduinos and such, and found some Murata dc-dc switching supplies at Mouser that are direct 78XX-series voltage regulator replacements. Dead simple, just DC-in, ground, DC-out. Don't even require any extra external components in most cases. They have 3.3V, 5V and 12V models at 0.5A or 2A capacities, and can handle up to 36V input. So looks like an easy way to go back to direct battery power if I ever want to! (Model numbers are like "Murata 7805SR".) Unfortunately the 12V models do require 15V in so not useful for making "perfect" 12V for things that want it from a 12V battery bank.

    I have an Apple Airport Extreme with external PSU, but the cost on that is high enough I've not wanted to experiment with it. If I ever needed to, guess I'd crack the case first and see what's inside...

    Most of the gear I'm using now has the 120V AC socket directly on the case, so not nearly so easy to switch over. My firewall/server is a FAR more capable box than the ARM, currently has a standard PSU but I've also run it with the "carputer" PSU and it does fine so could be converted easily enough. Most everything else either uses a higher DC voltage input or has the AC socket directly on the device so would require a bit more work...
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