Battery Powered Desktop

Nov 10, 2004
Has anyone around here tried it? could find ne thing about it on a search, but i was curious if it was possible to battery-power a desktop board with some creative electician work. Im curently in the planning phase of what i hope to be the ultimate portable desktop, with a relativley small overal size and the cabability of accessing any form of wireless that it could get its hands on (maybe even including the Verizon Wireless broadband service). anyway, i know most of the things such as HDDs and CD-Roms run on 12v, and i know my laptop is something like a 14.4v Lithium Ion. Anyway, ideas on why its not possible or how it could be done would be awesome :D thanks!

no...because desktop requires a lot of power....perhaps build a dothan/banias rig? but then again, the amount of power used will drain the battery real fast.

laptops uses like 60-100w~
So is it totaly impossible, hard to do, or just not worth it? you can run a pentium M on a 478 board, someone has already done that so that would lower power needs. could run a PCMCIA HD, all that kind of stuff. and this would be substantially bigger than a laptop, just smaller than a desktop :p so i think i could cram enough batteries in to create enough the 250-300 watt area. i was more curious about wireing a micro ATX mobo and molex connectors to a battery, and also have them connected to a batter in such a way that you could switch them back to a micro psu when you have that option. anyway, if im totaly out of my mind feel free to flame me off the forums ;) thanks again!
The amount of battery power you would need to power a desktop computer(plus monitor, I assume) would make the setup completely not portable. Just think of how big a standard household UPS is and how long it will run a computer. A great deal of the UPS is the battery, and the small ones only last for about 10-20 minutes. 12VDC ATX power supplies do exist, but you are still looking at a pretty considerable current draw. You might be able to get a couple hours off a car battery(not that you would actually want to use a car battery, though). If you are going to buy low power devices, a power supply, and batteries, why not just buy a laptop? I think it would be cheaper, not to mention more portable and nicer looking. There is no way in hell you would be able to get enough batteries packed into a case to be able to run the computer for more than half an hour.
This is [H], it's not about the cost it's about the bragging rights :) I personally haven't even heard of anything like that. and I'm no electrician but I remember hearing something about a motherboard that would run off the standard 4pin molex and used onboard resistors or something to create the 3.3 rail... maybe you could wire up your own resister board or something to take 12v and make it all the other volts it needs to be?
perhaps a good idea to achieve atleast 10 min battery backup incase of power outage, you will have enough time to stop what your doing and shut down properly, but what they have said above, it wont last that long. its worth a try thought, keep ya busy
DarkMonkey said:
This is [H], it's not about the cost it's about the bragging rights :) I personally haven't even heard of anything like that. and I'm no electrician but I remember hearing something about a motherboard that would run off the standard 4pin molex and used onboard resistors or something to create the 3.3 rail... maybe you could wire up your own resister board or something to take 12v and make it all the other volts it needs to be?
Even if the motherboard took 12VDC and nothing else, I would not hook a battery directly to it. The battery would probably start off above 12 volts and it would dip pretty low as it discharges. I would not want that feeding a motherboard. And resistors are absolutely horrible for voltage regulation. For one thing, resisters follow Ohm's law(duh), and so the voltage drop is dependent upon both the resistance and the current. This means the voltage will fluctuate widely as processor usage changes. Secondly, the voltage drop all goes to heat. When dealing with limited power such as in a battery situation, throwing away power to heat is a horrible idea.

This is certainly doable, and I would love to see it, but it is neither practical nor economical.
how can my laptop run on a battery the size of two cd cases put together for 2-4 hours while a desky couldnt run for more then 10 minutes on something 10 times bigger...makes no sense :confused:
When i ran on battery mode, i planning on only running vitals...(IE mobo, procc, ram, grfx, sound, HD) and turn off all unessicary stuff like CD-Rom, wireless cards that im not using, etc. im also planning on putting a p4m chip so i could use a very efficent cooler (such as the swiftech air cooler) and not even run the fan when on batteries. Also, i looking to have a (most likley) toshiba PCMCIA HD that ill run in a PCI slot, ATI 9600, and SB audigy2. doesnt sound like it could use all that much power, but what do i know? explanation as to what eats so much power in a desky as opposed to a laptop would be awesome :) thanks!
Well firstly, most laptops nowadays that get 2-4 hours of battery life use lithium ion batteries, which have very high energy density, and thus can pack a lot of power into a small space, but they are somewhat finicky and are not really available for general purpose use. For a project like you described, you would probably want to use some sort of sealed lead acid battery, which contains lead, which is quite heavy. That explains the battery aspect. Now on to power usage.

One of the main power draws is the processor. Laptops compensate by using mobile versions of processors(like you mentioned) and by throttling the processor speed down when on battery power. A laptop also probably uses only one fan, which might not even be on constantly. Next big power draw is the video card. Forget using batteries if you have a modern high-end video card, as they suck a lot of power. That 9600 will kill you. Get an older card and you will be better off. Drives are another major thing. Laptop drives use less power than desktop drives simply because they are smaller and they spin slower. I wouldn't necessarily bother with a pcmcia hard drive, though, since you would need a pcmcia adapter, which will use electricity. You can get a laptop drive and hook it up to a standard motherboard, though. Limit yourself to one hard drive. Optical drives use power, even when you don't have a cd in, so limit yourself to one of those, too. Cards use electricity, so I would try to get as much on the motherboard as possible(sound, etc.). One thing I don't think you have mentioned so far is a monitor. I assume you will be using an lcd monitor, right? I would try to stay fairly small on the monitor. There is a power usage estimator(you can probably find it over in the power supply forum) that will give you estimates for what each component draws. That might be beneficial in determining the best parts to use.

If you want a rough estimate of how long your computer will run on battery power, you can measure the current draw of your computer. Just get an ammeter and measure the current draw at the wall. Power supply efficiency will be a factor, but any 12V power supply will probably be similarly efficient. A high efficiency power supply would certainly be beneficial. After you have determined your current draw, multiply that by 10(120VAC at 1 amp is roughly equilalent to 12VDC at 10 amps). Next, determine the amphour rating of the battery you plan to use, and divide it by the DC current draw you just figured. For example, suppose your computer draws 1 amp at 120VAC and you want to use a 20 amphour battery. The computer will draw about 10 amps at 12VDC, and therefore will last about 2 hours on the battery. A 20 amphour leadacid battery is pretty substantial. I have a 55 amphour deep cycle battery downstairs that is the size of a car battery(and every bit as heavy).
You can do it with a DC to DC PSU and just wire it off a 12V Battery...however before you can get any portability your battery would be too small to run the computer for very long. It'd be better to just get a Laptop.
i think ive seen a battery that would run a desktop it said it was server graid and it costed liek 700 bux and had liek 3 battery pax's but that was a long ass time ago
Thanks for being thorough jpmkm, always appreciated :D
As for litium Ion, why not? has to be some way to get those kinda batteries in the specs im talking, and they are easy to recharge in addition :cool:

In terms of power usage, i saw an adapter that just nestles nicley into a PCI slot that will hold any type of PCMCIA card, including HDs. wouldnt that be the most efficent use of power? and like i said id not even power the CDROM when on batt. the mobo ive been looking at thus far (here ) does have both onboard video and audio, but id still like this thing to be able to play games...9600 is really out of the question? thatd be a major step down from my desky's x800...

In summary....I will NOT run:
Unessicary wireless adapters

want to run:
A MicroATX mobo
A Pentium 4M procc
An AGP Grfx card
A Monitor (14" LCD perhaps?)
USB Keyboard and Mouse
USB Internet adapter of some kind (probably just a cable to connect to a cell phone for wireless anywhere :D )

Off (if i can find it) a litium ion battery

Now were clear :) im going to try to find a battery that fits these specs, any input would be awesome still!
And just for the record, i already have a centrino 1.8ghz dothan Tablet, this is suposed to not be a laptop :D
Gaming is really going to kill battery life, as that will pretty much peg your processor and video card(two biggest power draws) at max usage for the duration that you are playing your game. Regarding the hard drive, a pci -> pcmcia convetor will use electricity in addition to powering the hard drive since it has to convert signals. Hooking a standard laptop hard drive to a motherboard will not use any additional power beyond what the hard drive uses since there is no signal conversion necessary. You would have to determine the current draws of the pcmcia hard drive and the standard hard drive and decide which is better. The difference will probably be quite insignificant, though.

The problem with lithium ion batteries is, like I said, they are finnicky. There are pretty strict limits on charge current, temperature, duration, etc. As such, they require fairly complicated charging circuitry. Laptops have the required circuitry to safely charge lithium ion batteries, but the general public does not. As such, general purpose lithium ion battiers are generally not available to the public, making it somewhat difficult for you to get ahold of them. I suppose you could hack up some laptop batteries or something, but you had better be damn careful or it could be dangerous. I think the best you could do is a sealed lead acid battery or a massive NiMH pack or something like that.

You say this is not supposed to be a laptop, but why? What are the advantages of this system over a laptop? It seems you would have to cripple it significantly to get any sort of battery life.
ATM this is all acedemic, hence talking to all of you instead of just setting in and building it.
Laptops are portable systems trying to be desktops, i want this to be a desktop that tries to be a portable.

Anyway, in terms of power needs, ive calculated that with something simular to what i said earlier that it would draw 220w.
70 of that estimate is to a P4 2.2ghz. Im planning to use the mobile version of that chip or one simular to it, so it should draw somewhat less.
another 70w is to the 9600. I have a PCI Voodoo4 laying around, and the max watage that pci grfx cards use according to the site is 37, which is a minimum of 33w savings.
in total, id expect it to run at around 185w conservatively.

Also, since my last post I emailed a company that packages Panasonic Litium Ions. They should be getting back to me with a price estimate relativley soon.

Lastly, I'd like to thank everyone who has put in their $.02, especialy jpmkm. Its people like you who make the [H]ardforum rock :D
Perhaps buy a UPS - uninteruptable power supply and strip what you need from that.
Not a good idea - what's the use / cool factor of a PC that is so heavy with batteries that it ISN'T mobile. And if it isn't mobile, why isn't it plugged in?

Sorry, can't see what is 'cool' & 'different' by not making any sense at all.
Lucidguy_3000 said:
Yea, but i want an hour at least...not just 10-15 minutes :( very good idea though :)

Like everybody has said, if you want a desktop...with a desktop processor, the thing that you are worrying about isn't voltage. It's mAH. To get a battery powerful enough to run your desktop for an hour...the system just wouldn't be portable anymore. The battery would just be too heavy.

Unless of course, you go for a Dothan/Banias desktop. You can buy Dothans/Banias's cheap on ebay and there's a DFI desktop board that runs them. Very powerful in gaming, very economical in power.

Just for fun, you can calculate the wattage of your system here:
Alright, after all that i think i could get about...45 minutes out of a 20amphour batt. If i can find a reasonable lithium ion battery that would do that, id be satisified. if not, then i scratch the project :D thanks for the help everyone, still have no idea how id wire it if i were to do it but hey, ill worry about that later if it comes up :) aloha

in laptops 3.6Ah battery is the size of a jewel still optimistic i can do this, but w/e, maybe ill be proven wrong :)
20 amphours is massive for a lithium ion battery. I assume you will have to use many lithium ion cells to get your 20 amphours. Supposing you got all your batteries together, how are you planning on charging them? Like I said earlier, lithium ion batteries and chargers are pretty difficult for the general public to purchase.
Lmao, nice.....
id be so stylin with that belt :p
Interms of getting the batteries, i emailed a company that makes custom litium ion packs from panasonic cells. im sure they'd have some kind of charging solution for it as well. I dont know how much it would cost, weight, or how bi git would be either. at this point im just waiting for a reply, ill check back with you guys 2morrow. Untill then, sleep well! :cool:
Just email them and say that you are some big american capitalistic pig with lots of money to spend.Say you are looking for a battery pack for some new product your company is building, and that you need a couple of their biggest packs for testing. Id bet it would work. :)
Corrugated said:
For the record, the drive is battery powered, not the computer.
really, i fallowed it way back when you were doing a worklog for pheaton... i must have misread it then, didnt really read the website that i linked to.
This idea is not really feasible with current technology. Especially if you actually want to do some gaming AND be mobile. It is possible to do what you say, but the size would be very big and bulky. Laptop manufacturers spend thousands of man hours and millions and millions of dollars to make the speed in the smallest package. I think if there were a reasonable solution, we would have already seen a computer of this type made by now.

I mean think of what you are asking for:
A computer that is powerfull enough to play games
Runs for at least an hour unwired to power source
Virtually mobile

If this was easily accomplished we would already have such products. Not trying to contradict, just being realistic by today's standards. If you do find a way, I would suggest not telling any of us though, patent that thing and make some big bucks... :)
KoZLop said:
A gas powered Generator. ;)

now THAT would be an idea!! since i'm not an electrical engineer, i wouldnt know the tech specs on it...but what about taking 2 nitro/gasoline engines 1.2 size+ and hooking that up to a small generator.

btw, what everyone is saying is family has 4 UPSs, each can power a monitor and a computer for 30 mins...but those bitches are sooo heavy...just bringing them into the room can take 2 people easily. 1 person if he is willing to break his back trying (me!!)
I would also hardly consider a gas powered generator mobile... :) Anyways, it seems easier to buy a laptop... Gaming laptops are quite powerfull now...
True that a laptop would be a easier solution, but i already have one of those :p
If i can do this and its under the size of a current mid tower or so, and weighs less than 40 lbs id b content. no word as of yet from the Lithium Ion company, lil slow in their responses. And yea, if i can do it im contemplating telling all you its impossible...then selling them to you! :D Thanks for all the input everyone.

BTW, id rather not be getting high off gas fumes while playing games. But thats just me :cool:
No offense, but I don't think any of us would buy one of these devices.
Yeah, I wouldn't buy one, it's rather pointless IMO given the current crop of laptops we have now.
what about a car BAT with some kind of alterating belt small to recharge it???????????