another 12v dc pc goes in use.

welp, i finally got my parts in and am running my new full powered (amd athlon 64bit) desktop pc on a 12v power supply!
this is basically the same 12v power supply ive used on my mini-itx webserver with alot of unique hardware, but this demonstrates adapting your standard desktop pc to run off a (200w in this case) 12v FANLESS power supply.

currently dont have any 12v plugs that will handle the startup current (but do have a nice little pile of blowse 2-3a fuses, ahem :wink:
so i grabbed one of my ac to dc adapters and am running it on that, and its still using a LOT less power than the standard pc's ac power supply. at LEAST 20w less. i currently have a cordless phone, router im testing out, and the pc through the killawatt and its idling at 75w, jumping to 80-90w when doing a disk search. the system was idling around 90-100watts! i am anxious to get eveything off it but the pc for later, and also to see what the even LOWER direct 12v draw will be (i pulled some 12v wire to my office a couple wks ago).
i also bought a metal piece to hookup the barrel connector to (normally where your ad-in cards are inserted on the back of the pc) .
clearly the common pc power supply isn't as efficient, as it can't be just the fan accounting for the 20w increase. i will get better numbers later and pics if people are interested. I actually offer this kind of thing (lower powered computing solutions) in my work, but most of you folks here are certainly capable of doing this thing yourselves if interested in saving power. Ill post more data and pics later. who hoo :):mrgreen:
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Comments

  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    Mattl,

    I am certainly interested. I hear you saying you have converted your desktop PC to run off of DC? That would be very neat! This fall I'll be building a offgrid home and would love to run my P4 box off of DC. I will be offgrid and am glad to learn of ways to use electricity more efficiently.

    Tom
  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    yes, well, it will be direct on 12v tomorrow (right now its on an ac/dc power supply that converts it to dc, ill have pics soon) , heres a link to the equipment i use for my solar website and the new stuff i am using on a standard desktop pc to make it run on 12v: http://www.mini-box.com/s.nl/sc.8/category.13/.f
    to run on a standard system thers another $5 part needed and they even solder it its the P4 atx 12v power supply, (pics will show it better)
    my families company is a reseller of anything you see there, but for small amounts youre better off getting direct from them.

    a couple of of the power supplies are rated for cars, one of those is what i use on my webserver as it will deal with the high voltages of the batteries charging.
  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    turns out im having a little issue when i run on 12v :( wondering if anyone has ideas?

    I hooked up today and the screen came up all doubled characters and wouldnt boot. i thought, maybe it cant handle the float voltage (13.4), tried tonight same thing. hard to describe, wierd thrumming sounds when the speakers are on.

    tried it tonight bats at 12.6 same deal.

    now heres the wierd: i run the thing off my modsine 300w inverter (the ac to dc adapter powering the 12v of the pc) and it wont startup, it startes but then kicks off, or does the same wird thing where the screen display goes doubled up strange, and the system makes odd beeps. the ac/dc adapter puts out a good steady 12v so what could be the issue?

    if i run the SAME ac/dc adapter plugged into the grid to power the system (plugged into my new 12v power supply) it works fine! it doesnt make sense, wont run off 12v direct or off the ac/dc inverter plugged into my 12v batts IF its running off the 12v. it seems to star t ok then goes funky.

    i have other 12v power supplies i can test but the other ones dont have the special extra 12v plug needed for the P4 processor power. my older pc does not need the extra 12v plug on the motherboard so i will try it with that. i just wonder if it is pulling to much power?? also, the killawatt when i plug the ac/dc converter it into the grid does not show anything like 300w (unless its too quick), it is showing (with just the pc plugged into it running off the ac/dc, a startup of 80-100w, then idling at 45/50w once booted. possible the killawatt isnt fast for a spike to be represented? when running off the 300w inverter it does beep at the same boot instance right after powerup so it looks like that (a spike).


    the 300w inverter does beep so i think its exceeding that on a short powerup burst but i dont get why the 15amp fuse isnt blowing on the direct 12v line. i picked up some 15a fuses at an auto place today for this and they fit fine, but is it possible that a wrong type fuse whould do something like this? maybe the fuse is limiting the current, can they do that?

    thanks!
  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    What is the actual voltage at the "12 volt" input terminals of your power supply when it's under full load? Wondering how long and what guage the 12 volt supply wires from the batteries are, that kind of thing. Perhaps the supply voltage is dropping too low at the input terminals as the full load comes on? That could well cause the "motorboating" sound in your speakers. Typical of supply voltage dropdout under load. Wouldn't be suprised, if you had a scope on the input terminals, that you'd see the supply voltage from the batteries jumping like a jack rabbit, in sync with the thumping from your speakers.
    Load comes on - supply voltage drops - load kicks off - voltage comes back up - load comes on - supply voltage drops - load kicks off, and on and on it goes.
    That's the very first thing I would check.
    If that's not it, sorry, I can't help ya.
    Good luck
    Wayne
  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    Re: another 12v dc pc goes in use.

    Ya I would be willing to bet your voltage is dropping to far on startup. Get a meter right on the input at the PC and what the voltage as you turn it on. Then do this again connected to the AC/DC power supply. I would be willing to bet when your using the AC/DC adapter it stays pretty stable around 12.5 or so and when you are running from your batteries it drops to 11 ish and the computer doesn't like it.

    If that is the case you could add a small SLA batter right behind the computer; sort of a buffer between the main battery bank and the computer. Then the smaller line won't be as much of an issue since the battery right at the computer would pick up an instantaneous load. Just make sure once it is up and running the voltage sag is still not too bad to completely deplete the small battery.

    Try running Niels wire calc for your distance.
    http://www.uwgb.edu/nevermab/voltage_drop_calculator_.xls
    if for instance you have #12 running 25 feet (50 feet round trip) and your startup is 120w or 10 amps that would be a voltage drop of almost 1 volt, and on startup it might be 15 to 20 amp surge trying to start up making the voltage drop even more.
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    thanks guys,

    i was thinking along the same line but:

    a) wouldnt the fuse blow?
    b) wouldn't the killawatt show a larger jump?


    i suppose if it is only 100/120 watts on startup and THAT is causing enough to voltage drop, I suppose it could be the distance, it is a rather long run and probably not large enough wire (a good 50', romex I think it is only 10Guage)

    i might return this 12v power supply for one of the automotive style ones, i do have a small 11AH battery foir nightlights i could move over as a test too.

    i will move this into the room where my pentametric is and watch trhe voltage and amps later tonight, but shouldnt the killawatt give mne a general idea or is it possible it is NOT quick enough? its shopwing 100 or so watts on starup running the ac/dc adapter and i know from experience its even less wattage running it straight dc , seems small to cause a voltage drop.

    also, if i was trying it at 13.4 even with a full voltagre drop i would have been in range. (specs:)

    Specifications, PW-200-M, PW-200-V
    Power Ratings (Max Power = 205 Watts, peak 250watts)
    12V 12A 13.5A Switched input
    12V input tolerance = 11V – 14V, 11-16V can be achieved with a simple trace cut. Consult the
    website for more information. Warranty is void after this alteration.

    still, maybe i am in range of the powersupply but its output isnt in range of the motherboard. hmm, bummer, ok i will try some of these suggestions and report, thanks!!
  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    I don't know for a fact but I think the Killawatt meter samples once per second.  When I turn on my window A/C with the meter set on watts it will read (for example) 248 watts and hold steady for ~ one second, then will read 621 watts for ~ one second, then 733 for ~ one second, then drop down to ~ 500 watts after startup surge has subsided and motor has stabilized.  Depending on where the clock cycle of the Killawatt is when I power on the A/C determines the wattage readings I get during the initial surge.  I get the same type of results from my refrigerator or any other motor that takes a few seconds to come to full speed.  Sounds like an interesting project though, good luck with it.

    Happy Easter

    Bad Apple
  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    Re: another 12v dc pc goes in use.

    Matt the other thing to try is connecting the AC supply in parallel to the 12v line from the batteries running to the PC. Then turn on the PC and once it is running pull the plug from the wall.

    I doubt the really quick spikes would show up that quick. And as the voltage does drop on the DC side I would be willing to bet it tries to pull even more power to compensate for the voltage sag. So a 120w load might pull 8.88 amps if the voltage did sag to 11.5 that would be 10.5 pulling the overall voltage down even more.

    I wouldn't think it would blow a fuse that fast. You can pull 20 amps on a typical 10 fuse for 20 seconds or so before blowing. It is all about heat build up and for short times they can pass quite a bit.
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    No, the fuse would not blow, because there isn't enough current getting through from the battery to run the computer, so there's no way there would be enough to blow the fuse if it's properly rated.
    Higher resistance (in the leads from the battery) = less current in amps (so no blown fuse) and not enough voltage to start computer. Some power supplies are designed to try and pull more current to make up for less voltage, but if there is already too much resistance in the lead wires, it won't have much success.
    That's what I expect you will find.
    Wayne
  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    cool, i still mean to try it in the other room: less wirelength and the pentametric is right there to see. it must be quick large spikes as the 350w inverter is crapping out which is shocking.

    paralleling the ac/dc would be too much work for something i wouldnt want to leave. i still have all of your suggestions to try but i started woirking ona song this weekend and there goes all the spare time and then some of my sleep ;)
    but definitely looking forward to resolving this one way or another. i wonder if i should have bought this:
    http://www.mini-box.com/s.nl/sc.8/category.13/it.A/id.424/.f

    the M2 has talk of surviving engine cranks etc. that probably would do the trick. I am using the pw80 for for website server and thats running great during all kinds of voltage situations (even did an eq with it running today) but that doesnt pull anything like the same power as this thing.
    i will see if i can determine the issue before sending back, theyre pretty good about returns. what i wish i could do is lower the power use of the machine but i suspect the main culprit is the fast cpu. this actually HAS lowered the power draw oif the machine as i was saying but strill i want it running direct on 12v. will report back when i can test some stuff thanks!
  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    Re: another 12v dc pc goes in use.

    I have to ask how hard it is to swap this all out. I would like to swap out my home PC (dell 2 gig) for 12v use and it is about 15 feet from the battery bank. Do these supplies work with a regular PC? Is it as simple as just swapping leads from my existing power supply? I had to get a new supply last year, my original one died and it was a pretty straight swap except for not fitting in the case like the original, but works fine.
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    oh yeah its easy. if you changed the pc power supply its that easy, except a big boix its a little circuit board.
    you may need a couple extras like the p4 power supply plig (4pin) ($4) , and atx extension cable ($8), and a way to mount your pc's new barel size power plug connector ($2). ONCE IM fixed ILL TAKE PIX AND POST i am sorry this turned into a request for help as i owuld have moved it to another forum.

    i have tried the system at the other shorter run and the pentametric doesnt show any huge spike either.
    i hooked up the power supply to another system that is a P4 (and i dont know how it compares powerwise) but it did almost the samew thing: spun the cpuy fan too slow and didnt even start up. this one would probably work great on a lower wattage (slower) pc.

    i have another 80w one if you have a system that doesnt exceed 80w and doesnt need the extra P 4 power connector like this: http://www.mini-box.com/s.nl/sc.8/category.20/it.A/id.303/.f

    heres some direct links to stuff im talking about:
    probably need this:
    http://www.mini-box.com/s.nl/sc.8/category.20/it.A/id.163/.f
    http://www.mini-box.com/s.nl/sc.8/category.20/it.A/id.208/.f
    the power supplies sare all rated diffferently for wattage, inopu voltages etc.
    I use the pw80 on my mini-itx (great low power platform do a goodle or look at same site) as it deals very well with voltage fluctuations and keeps my server running.

    i just emailed them to see what they say about the M2 power suplpy solving my problem.


  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    hey, interestingly in all of this i found some settings in the computer's bios to slow it down a bit (and lower its idle to about 50w, 40w w/out the dvd burnder plugged in). its a little slower but i can live w/it certainly.
    well, i just tried the pc on the 350w inverter->wallwart ac to dc -> pw200 12v power supply and it worked! pentametric showed me pulling about 6-7 amps on startup, about 5.3a idle (about 64w, compared to about 40w idling on ac, the 350 modsine inverter causing the extra. im really excited to see how little it uses on 12v direct (one of these days ;)
    i recall the difference running my webserver was pretty notable going on straight dc w/out the inverter anymore.

    but it still wont boot on the 12v direct over the cable i have, probably the cable is too long/small.
  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    wow, im running my pc on my "extra" power now that the batts are charged. so cool. mx60 pulls about 70w running it (90w startup) and keepin my batts floating. nice to make use of this little cheap modsine inverter i have. still i ordered my M2 power supply just now i want to go straight DC. right now is going dc to ac to dc, ugh!

    support told me the pw200 i have isnt meant for battery use (DUH me). while i have no doubt it'll deal with voltage fluctuations i'm still not sure if it'll havdle the startup current, though the docs (which ive read this time, ahem ;) say its disgned for newer P4 computers. it'll take a week till i get it so ill post back w/news.



  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.


    There are much wiser heads than mine here, but wouldn't one of those startup
    capacitors work for getting your computer humming?

    brad
  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    Hi Brad,

    Don't know, i recall going through this issue before with my solar powered server, as it didnt like the high voltage when the batts absorbed I decided then it was best to get something to regulate the voltage as i am not an electronics person. so i found powersupplies (pw80 has wide input voltage and powers a pc up to 80 watts) that are made for this. an alternative is something like these
    http://newenglandsolar.com/catalog_pages/catalog56.htm
    (for those of ous not comfortable or willing to do electronics products).

    in fact i was going to use that on my pc but wanted something self containined in the pc.
    i am going to get stuck with a 15% restocking fee on the pw200 i have (powers pc's up to 200w but doesnt handle wide input voltages) so if anyone wants to buy it for the new price with free shipping and no tax ($60) let me know. it definitely works fine (typing this on it) if the power is kept steady as that device would do. personally i like being able to plug in the computer anywhere and not having a special regulated outlet in a certain location, so if no ones interested i'll be sending that back once i get the new one (those M2's are about $100 btw). oh, i also have a little 70w dc atx power supply if anyone wants that cheap too ($25) but it also will not like high voltages of batteries absorbing/eqing unless externally regulated.
  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    Re: another 12v dc pc goes in use.

    So what voltage does it want? What is the input range?
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    Specifications, PW-200-M, PW-200-V
    Power Ratings (Max Power = 205 Watts, peak 250watts)
    12V 12A 13.5A Switched input
    12V input tolerance = 11V – 14V, 11-16V can be achieved with a simple trace cut. Consult the
    website for more information. Warranty is void after this alteration.


    it also has the 12v P4 plug soldered on it too which was an extra $5.00 item. if you look in your system youd see if you need it or not, if not just dont plug that part in. and if you look at the shape of them, you might need to get a atx extention cable (posted a link in one of my previous posts, about $5.00) as it likely wont fit. it might work with your batts as they dont absorb that high do they?

    if you are interested i dont want to send it out till i get my replacement though , but that will be w/in a week.
  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    Re: another 12v dc pc goes in use.

    I am confused, you said it wasn't suppose to be used with batteries? But if it takes 11-14 that should be fine (except for absorb)? I do absorb up to 14.4.
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    i know, thats what they told me. the ones that are designed for batts will do 6-36v or something ridiculous like that.
  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    Re: another 12v dc pc goes in use.

    Ahhhhhh
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    well the cool thing is that the cheapo 350w 12v inverter im running off now works just fine across absorb voltages so its not an issue really (except that i want to get it as low as she goes, so that maybe i can do this in winter sometimes too).

    its great to have 12v in my office/home studio now: i recorded some of the gtr on my latest song running the amp off 12v :) ( a cool little roland 2 watt amp that has good sounds for recording). hope to record the entire next song of solar, pc, amps, mics everything. :mrgreen:
  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    ok guys: i got my new 12v power supply which regulates output and its the same deal as the last, starts up ok but then craps out (when the drive spins up theres a larger draw of power and thats when it happens. i i just measured the 12v rail _after the powersupply in the pc but before the hard drive (easiest way i could tap with the meter). on startuop i saw the 12v drop to 11.6, this particular power supply is rated 11-14v. i had to unplug the dvd burner as that appears to be pulling another 10 watts if you can believe that nonsense. (other dvd drive on the web server doesnt pull as much). so i suppose its possible that its dropping below 11 on the input. the 12v input leads are easier to get to on the input side of the car power supply which is supposed to regulate the output. i will install that and test. but heres the wierd thing: the car one is supposed to deal with drops as severe as 6v and as high as 28v. . i doubt im dropping that low. well, ill report back with the better rated one plugged in.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: another 12v dc pc goes in use.

    matt,
    without me picking pieces of this throughout the posting areas i gather you are trying to run a 12vdc battery through this power supply for the laptop and are seeing a large voltage drop. this could be a number of things from the supply being overly rated for the job(meaning not good enough) to a battery being too small and/or wires too long and too small and even the combination of all the above too. if you think it's the wires use the voltage drop calculator. you already know the current it's supposed to draw by your measuring before from the wal wort and that's the current you'll use in the program instead of using the current of a pv. add to that your total wire lengths and the gage of it and it'll tell you a great deal about that part of the project and how much that contributes to the voltages being dropped.
  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    cool thanks, i did not know wire guage and length could affect how much the voltage drops. it must be that. i just measured off the 12v directly and it did in fact drop to 8v which surprised me. it is still within spec but im betting it is a quick drop to 6 or so. bummer, ill checkout your loss calculator.
  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    I hit that nail on the head 11 days ago. LOL
    Wayne
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: another 12v dc pc goes in use.

    ouch, i bet that hurt. no i'm not going to ask the next question as i'm not so sure i want to know. :-o :roll: :-D :-D :-D
  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    Not to worry Niel, it's just me giving myself a pat on the back. :evil:
    But it's OK, I'm sure I'll soon be eating humble pie - - again! :oops:
    You know, "Pride goeth before a fall". :-D
    Wayne
  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    youre right wayne, when i got the new power supply in and had the same lack of results i came back to this forum and started from the top, seeing your suggestion to measure at the input.

    going straight off batts was 13.1 (end of float just about ), turned it on drop to 8v, i was shocked. i took a quick look at the calculator looks greek, ill study/try it out later for sure.

    could unhealthy batts also account for large voltage drops too? mine were damaged first year i think , the symptom being they always are a tenth of a volt lower than normal, ie: they drop to 12.6 too easily at evenings. so i seem to have less csapacity they do ok as i normally just have the webserver (1-2amps), charge my notebook (3-4amps temporarily) some small battery charging uses,. and lights . i am quite sure the last leg of the 12v run to the pc is too small of a wire its just something i had. ok next step is the excel spreadsheet, thanks everybody
  • System2
    System2 Posts: 6,290 admin
    Re: another 12v dc pc goes in use.

    Where were you measuring the 8 volts? Was it right at the batteries, or at the end of the long 12 volt wires, that feed your computer?
    Since everything else seems to be operating OK, I'm sure it was at the end of the long feed wires, but just want to make sure.
    If it was at the batteries, then they are history.
    If at the computer, then it's higher than acceptable resistance in your feed wires from the batteries.
    Take care and good luck.
    Wayne