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Mac mini Sans Wires - Batteries Inside the Case

timothy posted more than 8 years ago | from the why-do-you-ask-why dept.

Hardware Hacking 317

An anonymous reader writes "Running Debian (or Linux generally) on a Mac mini is old news. Silas installed rechargable batteries inside the case, delivering a couple of hours of runtime while retaining the small form factor. Although it runs fine without wires, he had to plug in the monitor to be able to show that it was really up."

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FP? (-1, Offtopic)

Anonymous Coward | more than 8 years ago | (#12565997)

FP bitches!

Re:FP? (-1, Troll)

Anonymous Coward | more than 8 years ago | (#12566086)

Yoda quivered as felt Master Windu's mighty black cock entered his furry left ear. "Fuck me harder, you must!"

sheesh (-1, Troll)

Anonymous Coward | more than 8 years ago | (#12566001)

who cares? batteries are also old news :)

iMac (2, Interesting)

Mensa Babe (675349) | more than 8 years ago | (#12566007)

Using an iMac would be a better idea, for it has a monitor already included.

Yes, but (5, Insightful)

killa62 (828317) | more than 8 years ago | (#12566051)

the monitor would drain the batteries like hell

Re:Yes, but (1)

Eravau (12435) | more than 8 years ago | (#12566389)

I think the point being made is that if you have to have one power cable for the monitor anyway, why not use the iMac with its one power cable and not have to worry about your power running out in only two hours.

Re:iMac (0)

Anonymous Coward | more than 8 years ago | (#12566067)

...but that would require quite some juice.

Re:iMac (1)

Barnoid (263111) | more than 8 years ago | (#12566158)

only on slashdot: don't put the obvious <irony></irony> tags, and you'll get modded "+5 Interesting"

Re:iMac (0)

Anonymous Coward | more than 8 years ago | (#12566210)

How could such a post be modded as interesting?!?

Oh oh oh... Use a mouse to make working with the GUI easier! Yes! Interesting!

Guaranteed Karma Whoring (-1, Troll)

Anonymous Coward | more than 8 years ago | (#12566229)

Buy _____ from Apple. They are teh roxor!

Even better! (1, Funny)

Anonymous Coward | more than 8 years ago | (#12566309)

Even better... try it with a PowerBook. The monitor and the batteries are already included!

Re:iMac (1)

SlinkyDink2004 (812208) | more than 8 years ago | (#12566311)

Why not use an UPS? They are dirt cheap and no modifications are needed.

Re:iMac (1)

brontus3927 (865730) | more than 8 years ago | (#12566429)

My experience with UPS is that they are usually a good deal larger than a MacMini and most are also going to have several unneeded outlets if your using it as a headless server.

Also, if its use includes being moved about every so often, then this way it can stay up during transport. Or maybe its purpose is to act as a server for only short periods of time such as a LAN party or a lecture. Although, for either of those uses, it would be better if the batteries held up a bit better than that, but for a first try, not bad.

And the use would be? (0, Flamebait)

PIPBoy3000 (619296) | more than 8 years ago | (#12566008)

What exactly do you do with a Mac mini that you can't get any visual output from, especially one with a lifespan of two hours? It seems pointless to make it mobile.

Wireless network games? Find the server before the batteries die?

Re:And the use would be? (1) troll (593289) | more than 8 years ago | (#12566036)

I havn't read the fucking article so I don't know if its possible, but the best use would be just using the battery as backup and having a fileserver that can last a few hours even in a power outage.

Re:And the use would be? (1)

justforaday (560408) | more than 8 years ago | (#12566142)

Hmmm, wouldn't a UPS be better for that sort of thing?

Re:And the use would be? (1)

nine-times (778537) | more than 8 years ago | (#12566326)

But an UPS would be big and clunky. If you're using a mini for any kind of a headless server, size is probably an issue.

Re:And the use would be? (-1, Troll)

Anonymous Coward | more than 8 years ago | (#12566049)

The use, my young padawan, is to get more Apple-zealotry on the Slashdot-mainpage.

As you should know by now, the OSTG receives a certain amount of "support" from Apple, and reciproces the favor by posting "interesting news" about Apple.

Re:And the use would be? (5, Insightful)

Skynet (37427) | more than 8 years ago | (#12566053)

Since when did nerds need a reason to do something nerdy?

This is Slashdot!

Re:And the use would be? (0)

Anonymous Coward | more than 8 years ago | (#12566255)

Since when is a computer that runs on batteries new or nerdy?

And since we're talking about Apple: s/ner/tren/;

Re:And the use would be? (0)

Anonymous Coward | more than 8 years ago | (#12566362)

Reinventing the "portable computer" is not nerdy. Laptop computers are commonplace and I bet we all have seen a ultra small subnotebook before, perhaps even own one.

Even though soldering a battery to a small case computer is nerdier than just plugging it into a factory built battery slot and calling it a notebook, but the total nerd factor is still way below room temperature.

Gumstix have nerd value. Power-over-ethernet powered Gumstix even more. A notebook computer without high battery nor comnputing power has none. It is not very small, not very power efficient, not very fast, requires no impressive tinkering and has no advantages over any existing technology. Tell me where this nerdy then...

Re:And the use would be? (5, Insightful)

hey! (33014) | more than 8 years ago | (#12566077)

And the use would be?

As a random act of senseless beauty.

You see, geeks do have poetry in their souls. It's just in a language they don't teach in the English department.

So -- do what appeals to you. The utility will come later.

Re:And the use would be? (4, Funny)

FunWithHeadlines (644929) | more than 8 years ago | (#12566102)

"What exactly do you do with a Mac mini that you can't get any visual output from"

Bah! Real programmers don't need screens. Why, in my day we didn't even need keyboards to issue our commands. We merely bellowed at the computer and it whimpered off to do what we wanted. Honestly, the kids these days...

Re:And the use would be? (4, Funny)

YomikoReadman (678084) | more than 8 years ago | (#12566310)

When I saw this, it reminded me of a very old joke I saw once.. and compelled me to post it here.

Top 12 Things A Klingon Programmer Would Say

12. Specifications are for the weak and timid!

11. This machine is a piece of GAGH! I need dual processors if I am to do battle with this code!

10. You cannot really appreciate Dilbert unless you've read it in the original Klingon.

9. Indentation?! -- I will show you how to indent when I indent your skull!

8. What is this talk of 'release'? Klingons do not make software 'releases'. Our software 'escapes' leaving a bloody trail of designers and quality assurance people in its wake.

7. Klingon function calls do not have 'parameters' -- they have 'arguments' -- and they ALWAYS WIN THEM.

6. Debugging? Klingons do not debug. Our software does not coddle the weak.

5. I have challenged the entire quality assurance team to a Bat-Leth contest. They will not concern us again.

4. A TRUE Klingon Warrior does not comment his code!

3. By filing this SCR you have challenged the honor of my family. Prepare to die!

2. You question the worthiness of my code? I should kill you where you stand!

1. Our users will know fear and cower before our software. Ship it! Ship it, and let them flee like the dogs they are!

Seeing as how old school programmers think like klingon programmers, I believe that it can be reasonably assumed that all old programmers are klingon.

Re:And the use would be? (1)

archivis (100368) | more than 8 years ago | (#12566437)

*imagines the quality of Klingon code*
So...Microsoft is a Klingon outfit?

That explains sooooooooooo much.

Re:And the use would be? (1, Funny)

Anonymous Coward | more than 8 years ago | (#12566339)

Oh yea? I bet you used a hard drive and an "operating system" too .. pfft.

In *my* day we used to edit inodes by hand on floppy disks with a magnet and a paperclip!

Re:And the use would be? (4, Funny)

Cecil (37810) | more than 8 years ago | (#12566169)

It's a portable wireless hard drive for my laptop. Duh.

Re:And the use would be? (2, Insightful)

jellomizer (103300) | more than 8 years ago | (#12566230)

2 hours isn't to bad. Think of it as an imbedded UPS. for your system.
Preventing data loss on an accedental power outage.

Secondly if this job is done right it could help improve the life of the computer, giving the system a reliable source of power helps keep the equiptment from those little surges and dips.

Portability. 2 Hours should be enough to get you to your location without bringing the system down. So when you get to the office and quitly plug in the system to the projector bingo your keynote presintation is ready on the first page.

Convience. You have to compile your project and finish it at home. While you are driving home the code is compiling. When you get there and put power back on it is ready to test.

The Mac Mini is less of a PC and more like a Portible Laptop Computer without the extras,

Vision analysis for a robot (0)

Anonymous Coward | more than 8 years ago | (#12566244)

I build lego and meccano robots for fun but blind robots are frustrating.

This modded mac-mini looks perfect to allow me attach a webcam to my robots and let them see objects rather than have to rely on touch sensors. It should also allow me to build in a capability of a virtual world, ie:to allow a robot to remember what is no longer in view and recognise if something has been moved or removed when it wasn't looking in that direction.

Quiet Macs (2, Insightful)

FunWithHeadlines (644929) | more than 8 years ago | (#12566010)

"Although it runs fine without wires, he had to plug in the monitor to be able to show that it was really up."

Helps that Macs generally (yes, there are exceptions) run whisper quiet. Is the computer on? With a PC, just listen for the fan noise. With a Mac, hmm..can't tell, better look at the screen.

Re:Quiet Macs (2, Interesting)

freeplatypus (846535) | more than 8 years ago | (#12566094)

Wake up Neo. This is a dream. This is a big lie!

If You think that 20dB from the PC case is a lot then maybe You should think it over.

Re:Quiet Macs (2, Interesting)

clontzman (325677) | more than 8 years ago | (#12566095)

Er... yeah, tell that to the wind tunnels I've had under my desk for the past couple years -- first an MDD, now a G5. Nice, yes, but quiet they ain't.

PC's engineered to be quiet are quiet. My Dell is nearly silent. Macs engineered to be quiet are also quiet. It has nothing to do with the platform.

Re:Quiet Macs (2, Interesting)

jrockway (229604) | more than 8 years ago | (#12566183)

We have "silent" MPC computers in one of our computer labs. The silence is a copmromise between noise and melting the processor. Once in a while, we install a gaming image onto these machines... but it's pretty much useless because every single machine crashes solid after about ten minutes of gaming.

Silent != good.

Re:Quiet Macs (1)

FunWithHeadlines (644929) | more than 8 years ago | (#12566290)


I specifically wrote " generally (yes, there are exceptions)" to avoid this sort of response, by pre-acknowledging what you later wrote. I'm well aware of the wind tunnel Macs, but they are the exceptions. The iMac -- very quiet. Powerbooks -- silent. iBooks -- silent. Mac mini? I've heard silent too, and in fact that was the whole point of this thread. I was responding to an aspect of the mini in question from the article.

Re:Quiet Macs (1)

geoffspear (692508) | more than 8 years ago | (#12566349)

My Powerbook sounds like a jet engine is starting up on my lap when it gets too warm. Granted it's an older titanium model and I haven't used any of the new ones, but it's definitely not silent.

Re:Quiet Macs (0)

Anonymous Coward | more than 8 years ago | (#12566444)

> The iMac -- very quiet. Powerbooks -- silent. iBooks -- silent.

You should look around on forums for "iMac G5" or "Powerbook" and "fan noise" sometimes. There have been numerous complaints about the G5s and especially the 12" PB noise.

Re:Quiet Macs (1)

endx7 (706884) | more than 8 years ago | (#12566327)

My Dell is nearly silent.

I had to use a dell for a while, and it was unnerving. The lack of fan noise I mean.

I felt a lot better once I got back to a computer I could hear.

Re:Quiet Macs (1, Funny)

Anonymous Coward | more than 8 years ago | (#12566335)

With a PC, just listen for the fan noise

That would only tell you that you've got enough power to run the fans.

Re:Quiet Macs (2, Interesting)

adam1101 (805240) | more than 8 years ago | (#12566390)

> With a PC, just listen for the fan noise.

One of the biggest reasons that Mac-PC hardware comparisons are doomed to fail is that there is no such thing as "a PC". Most PCs are loud. But there are many PCs that are quieter than desktop Macs. Many PC laptops are heavy, loud, hot and have short battery lives. But there are PC laptops that are lighter, cooler, quieter (fanless 1.1ghz Pentium-M) and have longer battery lives than any Mac 'Book. Mac fans invariably pick the worst PCs to compare with while PC fans pick the best (which are usually more expensive as well). More on topic: I've been running a fanless 1.4ghz Athlon XP-M on my desktop for over a year. I doubt any Mac is more quiet.

Umm... Whats the monitor for? (1)

bodfa (656636) | more than 8 years ago | (#12566024)

Looks like a black screen on the monitor... Maybe he uses a blank screensaver :)

Re:Umm... Whats the monitor for? (1)

Loco3KGT (141999) | more than 8 years ago | (#12566248)

You mean you haven't seen the new version of Aqua?

You're sooo 1Q 2005.

and then... (0, Offtopic)

PooR_IndiaN (876413) | more than 8 years ago | (#12566025)

and then...

and thus (0)

Anonymous Coward | more than 8 years ago | (#12566071)

spake Zarathustra

Re:and then... (1)

Phu5ion (838043) | more than 8 years ago | (#12566129)

No "and then"!

Mini Mac (0, Redundant)

bitswapper (805265) | more than 8 years ago | (#12566031)

Hang on, MiniMac! If you were to go down, I don't know what I'd do.
I'd be inconsolable for ... a few minutes .. I don't know ... whatever.

sniff sniff (1)

BobVila (592015) | more than 8 years ago | (#12566037)

It sounds perfect for hiding in the ceiling tiles.

Re:sniff sniff (2, Interesting)

hey! (33014) | more than 8 years ago | (#12566118)

Not quite, cause you'd have to get it up there right before the packets you were interested in hit the network.

However -- figure out some way to parasitically power it off the wiring going to the flourescent lights, in a way that can be installed in one or two minutes, then you'd really have something.

Sans? (-1, Offtopic)

Anonymous Coward | more than 8 years ago | (#12566052)

Use real words instead if you can. Thank you.

Re:Sans? (2, Funny)

chiark (36404) | more than 8 years ago | (#12566177)

I (am || can speak) French, you inconsiderate clod!

Re:Sans? (2, Funny)

Anonymous Coward | more than 8 years ago | (#12566305)

Illiterate clod.

Awesome... (0)

Anonymous Coward | more than 8 years ago | (#12566055)

Now do it with solar power! //MMN-o

External Batty pack + VCN (3, Informative)

JawzX (3756) | more than 8 years ago | (#12566062)

VNC is the obvious way to talk to the machine without a monitor connected...

If an external battery could be housed in a mac mini form factor external case (stacked under/ontop of the mini) I bet battery life could be equivelent or longer than a power-book (no LCD to run). Could provide some interesting low-cost remote monitoring solutions...

Re:External Batty pack + VNC (0)

Anonymous Coward | more than 8 years ago | (#12566135)

Macs are sometimes a little too smart for VNC -- if they do not detect a monitor connected, they do not create a console display and the VNC server will fail because it does not have a display to serve. You need a dummy adapter on the monitor connection to fake the computer into creating a display.

Re:External Batty pack + VNC (3, Interesting)

jamie (78724) | more than 8 years ago | (#12566246)

Macs are sometimes a little too smart for VNC -- if they do not detect a monitor connected, they do not create a console display and the VNC server will fail because it does not have a display

Old Macs, maybe. I had to plug in a display dongle to a Mac IIci server back around 1995. But the Mac mini doesn't need one. I have a mini in my basement, and it works fine over VNC with nothing plugged into its video port.

Re:External Batty pack + VNC (0)

Anonymous Coward | more than 8 years ago | (#12566403)

Do you have a keyboard or mouse hooked up to it? I'm just curious because I'm having much the same problem as the parent said. It seems like VNC will not come up unless there is a screen attached first so the mac can figure out the resolution. I've only had a few days to take a crack at it however so I could have something set up wrong.

Re:External Batty pack + VNC (1)

stratjakt (596332) | more than 8 years ago | (#12566256)

Only an Apple zealot would call that a "smart feature".

The XBox does the same thing. Turn it on without anything plugged into the A/V ports, it flashes red/green as if the unit was faulty. Plenty of people have taken perfectly good units back to Best Buy (or wherever) claiming they were broken out of the box, which of course fueled a whole bunch of "Ms is teh gay xboxes are broked" dipshittery right here on slashdot.

Anyhow, you can run VNC on a virtual framebuffer under linux or BSD, don't see why you couldn't do it on a miniMac.

Big deal (-1, Troll)

Anonymous Coward | more than 8 years ago | (#12566069)

I find it interesting that the mac heads out there have to constantly be defending their computers. I guess it is because they spent too much on too little of a machine. Truth hurts.

Re:Big deal (0)

Anonymous Coward | more than 8 years ago | (#12566147)

I find it funny that Windows users don't mind rebooting 5 times a day, Don't change when the machine loses their data. Truth hurts.

Re:Big deal (1)

WhatAmIDoingHere (742870) | more than 8 years ago | (#12566259)

My XP Pro machine has been up for 36 hours. Before that it was up for a week. And before that, 4 weeks.

Think before you speak, boy.


shird (566377) | more than 8 years ago | (#12566088)

heh, just kidding.

old news? (0, Offtopic)

justforaday (560408) | more than 8 years ago | (#12566097)

Old news? That must be why slashdot posted that story only a week ago...

Great, or not really? (1, Insightful)

Niekie (884742) | more than 8 years ago | (#12566109)

Hmmm.. a system powered by batteries, but not the monitor? So what's the use then? Taking it with you to places without power? No. No power for the monitor.. Using it at home? No. You could just plug the thing in and not waste the poor batteries. The only thing they have to come up with next, is either a monitor that runs off batteries, or just lower the prices of laptops. (Which would probably be a better deal then this anyway, since this new system will ofcourse cost lots of money.)

Re:Great, or not really? (1)

mrch0mp3rs (864814) | more than 8 years ago | (#12566146)

Two Words: Wireless Server

Re:Great, or not really? (1)

Niekie (884742) | more than 8 years ago | (#12566216)

Use it as a Wireless server? How would you want to pull that one off? I don't think the uptime would be very long, considering it's battery powered.. catch my drift?

Re:Great, or not really? (1)

mrch0mp3rs (864814) | more than 8 years ago | (#12566392)

Well, I think a lot depends on the battery, doesn't it?

Since the Mac Mini uses mostly iBook parts, I tend to think that the Airport Extreme (802.11g) and Bluetooth functionality is already somewhat energy conscious.

I would apply this solution for a host of demonstration and training purposes -- anywhere where I need to demonstrate any kind of client-server network interaction and I need to control all the enviromental variables. If I can't rely on Internet connectivity (and trust me -- I've been screwed on this a couple of times in the last few weeks), I could just bring a couple of laptops that work with the mac mini as my application/db server for demo purposes.

Would the battery life last 8 hours? Certainly not. But it might last 4 depending on the battery, and for $500 + change, that's a heck of a nice little server to take on the road with you.

Thats nothing (4, Funny)

Timesprout (579035) | more than 8 years ago | (#12566134)

wait till you see my gerbil powered mini. I'm having a small problem with it though, it runs just fine in my test harness but the power seems to tail off and then die shortly after I hermetically seal the case.

4Ah 20V battery and 1:50 runtime = 40W draw? (4, Interesting)

Anonymous Coward | more than 8 years ago | (#12566140)

The author says he measured 14-20W for the mac mini under load, but his 80W-Hr battery only lasted 1H:50M, implying a 40W+ power draw.

Am I missing something?

Re:4Ah 20V battery and 1:50 runtime = 40W draw? (0)

Anonymous Coward | more than 8 years ago | (#12566406)

>>Am I missing something?
I remember reading a toms hardware review, they mentioned it consumed 28 watts while playing dvds

Re:4Ah 20V battery and 1:50 runtime = 40W draw? (1)

v1 (525388) | more than 8 years ago | (#12566458)

Macs do draw that low of power. My powerbook g4 draws at most 28 watts when charging the battery and playing UT 2004 at the same time. (graphics and CPU maxed out) It draws 18 watts under normal use, and 2 watts asleep OR off when not charging batteries.

Not sure why his unit only lasted 2 hrs though. The author mentioned the computer will run off from 12-20v, and it seems like he had enough cells to keep the voltage up until they wound down all the way. G4 processors are good at conserving energy, and run cool and lean when they're not busy doing things. (I never understood why do PCs run full tilt all the time?) It's possible he made his measurements with the machine idle, and then in the actual test was actively using the machine, increasing its power consumption. I can't fault your math, but 40w seems excessive for a mini. The mini's pack is rated 85w, but that's to power USB and firewire too.

Mac Mini was already basically a notebook computer (0)

Anonymous Coward | more than 8 years ago | (#12566145)

without the screen. The hardware used was notebook rated hardware. The cost of making the machine itself moble is more then buying a notebook all together.

I'd just have bought a UPS, because that is all this will be useful for.

Hmmm (0)

Anonymous Coward | more than 8 years ago | (#12566149)

If you modded a mac mini sans mac mini now that would be impressive. Although you would need to add a mac mini so you could connect a monitor to prove it was there, although then that would ruin your mod...

Kind of like a 21st century "tree falls in the forest" .

Huge new product line! (5, Funny)

dave_mcmillen (250780) | more than 8 years ago | (#12566152)

Hey, this could be the start of something big! What if he were to also install a portable screen? Maybe it could, I dunno, fold down into the top of the machine, or something. Then you could carry the computer around and do stuff with it, wherever you went, while resting it on your knee. A sort of "knee-top" compiter, though maybe there's a better name someone can think of . . .

Re:Huge new product line! (0)

Anonymous Coward | more than 8 years ago | (#12566214)

I think it would be awkward to have it resting on your knees, your thighs would probably be better. I think "thigh top" sounds good.

Re:Huge new product line! (-1, Flamebait)

stratjakt (596332) | more than 8 years ago | (#12566284)

Why don't you just shove it straight up your ass so it can dock with your iPod!

Call it a prostate-top!

Re:Huge new product line! (5, Funny)

nine-times (778537) | more than 8 years ago | (#12566402)

Bah... and what are you going to do for input? You can install a screen, but then you'd still have to carry around a keyboard and mouse. What, you're going to attach a keyboard and mouse to this whole setup? It's patently absurd.

Re:Huge new product line! (1)

Uruk (4907) | more than 8 years ago | (#12566446)

..Or maybe someone could make the Mac Mini even smaller, something that could sit on the "top" of your "palm". What kind of computer would they call that?

Here's the basic idea. You have several product lines: desktops, laptops, palm tops. Each line has a top of the market, and a bottom that provide the most and least features within that line, respectively. I think what we're seeing here is an instance of a phenomenon where the bottom of one product line can come into the neighborhood of the top of another product line.

Darwin award soon (5, Informative)

ballpoint (192660) | more than 8 years ago | (#12566162)

Exactly how is the LiPo battery charged ?

Without a proper charger, combining the energy density of a 80Wh battery with highly reactive Lithium is a recipe for disaster. 9187 []

wow, a revelation! (0, Troll)

Se7enLC (714730) | more than 8 years ago | (#12566164)

wow, we've reinvented the laptop, except we gave it a shorter battery life.

What exactly is the revelation of this project, again?

12W (4, Informative)

IceFox (18179) | more than 8 years ago | (#12566168)

Wow, at only 12W for the entire system? It is pretty hard to get a x86 box that low for that

-Benjamin Meyer

Re:12W (0)

Anonymous Coward | more than 8 years ago | (#12566206)

It seems to be more like 40W if he only got 1 hour and 50 minutes off an 80W-hr battery pack. A 12W system would have lasted several hours from an 80W-hr battery pack.

Re:12W (1)

the_2nd_coming (444906) | more than 8 years ago | (#12566387)

WiFi networking is a fixed wattage, so if that was turned off I am sure it would be close to 12 Watts.

UPS (1)

tezbobobo (879983) | more than 8 years ago | (#12566181)

Well, I for one see a use for this. If you could get it to cut in when power fails this could be very useful... even commercially so. I wouldn't think it would need to be to complex - such as sending messages to the interface - as I can usually tell when the power cuts out because of the lights going out.

Except on second thoughts you'd also have to insert batteries into the monitor to be able to shut down the machine properly.

Re:UPS (1)

child_of_mercy (168861) | more than 8 years ago | (#12566462)

I've had more late night call outs caused by Borked UPS's than I have by screwy power.

I'll grant you I live in a city with very, very regular power (Canberra).

I still hate UPS makers.

And as a side note... (0)

Anonymous Coward | more than 8 years ago | (#12566187) 5 years, they say that they may actually be able to produce a portable, battery-powered Mac with a 17" flat screen monitor, a powerful 1.67GHz PowerPC G4 processor, a standard 5400-rpm 100GB hard drive, an 8x SuperDrive, 2GB of DDR RAM and AirPort Extreme and Bluetooth 2.0+EDR built right in.

Wait a minute... []

Re:And as a side note... (1)

ari_j (90255) | more than 8 years ago | (#12566241)

...and better than two hours of battery life.

Article Text (5, Informative)

riffzifnab (449869) | more than 8 years ago | (#12566236)

Mac Mini Surgery

I had an itch to scratch so here it is...

Earlier this week I read an article on the Debian Weekly News, about a Debian box running on 3 Watts, and it reminded me of a project that I was asked to put on the shelf some time ago. The gist of the article linked to by the DWN was that Alex Perry got to wondering how much power his Linksys switch was sucking down whilst running 24/7, and found that his Manga, an ARM based router box, not only consumed less power but was able to run full blown Debian to boot. His point was "If I am going to pay to have a switch run 24/7, I might as well have the switch be a useful server as well." Following his article the PepLink community promptly got X11 working on the Manga and Alex's website was updated with the screen shots, which I might add are quite amusing.

While I do sympathize with the original thrust of the article, I must say that the Manga's ARM is a rather diminutive processor for a desktop machine these days. So my question is why would you run a Manga as a desktop to get down to the 3 Watt mark when for just a few more Watts you can run a box with a G4 processor? Yes, I am talking about that little machine that all of my geek friends (me included) seem to be drooling over as of late. The Mac Mini!

Several months ago I was in need of finding a small but powerful computer that could be run for a long period of time on batteries and not be a burden to carry. I was looking at several embedded options from places like kontron and mini-box, when I saw an article on the Mac Mini. Looking at the limited specs for the Mac Mini on Apple's website I began to suspect that if I removed the cdrom drive I would be able to fit a "lithium-ion polymer" battery pack inside the vacated space. I say that I suspected this because Apple is lousy about posting specs about internals and stuff that your Grandparents wouldn't normally ask about. So I ran down to the local Apple store with my trusty calipers and had one of their technicians go into the back and measure the dimensions of the cdrom drive for me. The numbers that he gave me made my day, the batteries would fit! Now about power specs. Apple of course did not have the DC power specs online, and nobody I talked to at the Apple store or on the support line could get them for me. In an act of desperation I resorted to sending email to combinations of addresses like,, etc asking for the specs. Funny enough I got a reply (No, not from Steve Jobs) from an Engineer who was quite helpful. It looked like the Mac could do it, so I decided to get one and hack on it. The Mac was dirt cheap compared to the embedded systems so it was a very limited risk approach to proceeding on the project.

I ordered the Mac, a 4GB Hitachi Microdrive, and a laptop-IDE to CF adapter. I also talked to Mike (Dr. Zhang) at SKC PowerTech, Inc, and he was kind enough to send me some batteries for evaluation. The batteries were a new design and were not yet in production, so there was a bit of a lead time on those, but at the end of two days I had the rest of the necessities at hand. First things first, I measured the out of the box power draw of the Mac Mini, which turned out to be only 12 Watts! This was better than the specs I was given. I then proceeded to remove the hard disk and replace it with the Microdrive-CF adapter setup. Then I got me a Debian (Sarge) disk *GRIN*. This was the first time I had touched a Mac, and I was pleased to find that the Debian install on the Mac was smooth and painless. After getting the system up and running, I did some stress testing on it. The testing involved running simultaneous FFT routines (like 30 of them) on 80MB data files. The system was so heavily loaded that it took about 15 minutes to log into the machine from another terminal, and another 15 minutes to get to the bash prompt. During this utter thrashing of the system the highest the power usage spiked to was 20 Watts, but it stayed around 14 Watts most of the time. This was impressive...

This is where the bad news came... The batteries came in, and not 30 minutes later I was informed that effective immediately my time had been re-prioritized. Which is why the project had been put on the shelf. After reading Alex's article I just had to make some time to hack on it, so a couple of nights ago I did, and I am pleased to report that the trial was a successs. Read on for the Tech details and pretty pictures...

Materials Source
1 Mac Mini Apple Computers
1 4GB Microdrive Hitachi
1 IDE to CF adapter
5 Li-ion polymer cells SKC PowerTech, Inc

Tools Needed
Putty Knife to open Mac
Small Phillips Screwdriver
Soldering Iron
An ESD workstation is recommended
Kapton Tape
Insulated Wire
Connectors are nice
Couldn't have done this with out my Fluke(TM) Multimeter

Getting Started

Disclaimer: I am not responsible for anything you do with the information you find on this site. If you are hacking hardware to make it do stuff it was not intended to do you are most likely voiding your warranty. This hack worked for me, but your mileage may vary.

Now that we have the formalities out of the way, the first thing that needed to be done was to open up the Mac, and disassemble it so that the battery power leads could be soldered onto the motherboard.
Mac Mini Motherboard
I placed the bare board on an ESD mat and plugged in the power cable. Then with my multimeter I probed the voltages on each pin on the power connector where it was soldered to the board. The Power cable has 10 conductors in it, 6 of which are neutral conductors, and 4 of which carry 18.66V DC. The neutral conductors are shorted electrically to the conductor's shield and the chassis ground. The connector has 5 pins soldered to the motherboard, and 3 spots where the shield is soldered to the motherboard. 2 of the pins (which have red wires soldered to them in the pictures below) are 18.66V, two of the pins are neutral, and the other pin is regulated inside the connector to 1.33V (which is used presumably to power the on/off switch). According to the Engineer at Apple, the Mac Mini should be able to operate anywhere between 20VDC and 10VDC. Caveat: If you plan on using the firewire port to power any external devices you cannot drop below 18.5VDC before those devices start to suffer power loss.

Live Conductor Wiring

You will notice that I used 2 strands of wire for both the 0V and 18V rails. I did this because I was using 24 Gauge wire to solder to the board, and wanted to make sure that I had a fat enough current path to the battery. I had to solder the 18V rails to the bottom of the motherboard because there was no other place that was accessible. Of the 0V rails I soldered one wire to the shield pin and the other to the shield itself (See the pictures below).

Notice the twisted quad coming off the board in the picture to the right. It probably isn't necessary since the system is going to be operating inside an RF shield (The Chassis), but it is neat and tidy, and it is better to be safe than sorry.

The Battery
To get the 18V nominal voltage that the system needs I used 5 of the SKC PowerTech cells wired in series which gave me a 4Ah 20V battery.

Caveat: There is not much room to stuff these in the Mac Mini. So make sure you use Kapton tape or similar because electrical tape will make the battery pack too thick!

Now that the battery is built and the Mac is ready to accept the battery, it was time to put the system back together. Here are all of the parts: Parts

Notice the piece of foam under the Microdrive. The adapter card does not have horizontal mounting holes so the foam was necessary to stabilize the card. I am planning on replacing it with a 6GB Microdrive which has a direct 40pin IDE connector when they become available.

The Moment of Truth
Caveat: There are a couple things I should note here, fortunately they can be easily dealt with. I will update this page when I have the fix. First, remember back in the wiring section when I said that there was a 1.33V pin power connector soldered to the motherboard? When I first plugged the battery in I was assuming that that pin would be regulated off of the 18V line on the battery, but apparently it is isolated and there seems to be a regulator inside the connector itself. So when I plugged in the battery and pushed the power button, to my disappointment nothing happened. I got out my voltmeter and measured the voltage off the battery and the voltage going to the board and everything seemed to be correct, so I plugged in the power cable and hit the power button... ...The Mac started right up, so I pulled out the power cable... ...And it kept right on going.

The second thing I wanted to mention, and this is IMPORTANT, these cells don't have a current regulator on them. So when you recharge them, do not use the Mac's power cord. Instead use a power supply which has a current limiting knob on it so that you can keep the current low whilst charging the batteries. Don't blame me if you plug in your Mac's power cable and it fries your power supply.

Debian in All it's Glory! Here is the Mac Mini...
running Debian...
On Batteries...

I have got better things to do with my time than sit around and watch a computer screen!!! Don't you wish you had 3-D glasses?

The Mac Mini ran for just over One Hour and 50 Minutes (1:50) on the Li-ion Polymer batteries!

Include a 1.33V voltage regulator to run the power switch.
Include a current regulator so that the battery can be charged from the power cable.
Needs a battery monitor for power management.
Configure suspend/sleep states.
Configure Wake On LAN.

Copyright © May 2005 Silas Bennett

Wireless network not available...? (1)

mrdogi (82975) | more than 8 years ago | (#12566249)

So, could they not just connect to the thing over a WLAN? I suppose, they couldn't verify that it was that specific mini...

Nuclear Battery (1)

COMON$ (806135) | more than 8 years ago | (#12566261)

Fit that nuclear battery as discussed on slashdot earlier that is supposed to be available into it and then I will be impressed, That would have some great possibilities.

Double power wires (1)

RainbowSix (105550) | more than 8 years ago | (#12566275)

He says that he used two wires for each power connection to ensure that it could carry enough current. Does this actually work? Doesn't electricity take the shortest path thus overloading the wire with the least resistance?

Re:Double power wires (1)

gadgetbox (872707) | more than 8 years ago | (#12566415)

No, using two wires is similar to using a larger gauge wire. It decreases the resistance, thereby allowing the path to carry more current safely with less heat dissipation.

Re:Double power wires (1)

hairykrishna (740240) | more than 8 years ago | (#12566464)

No, it's like a circuit with two resistors in parallel ('cos that's essentially what it is).

Old news (-1, Troll)

/ASCII (86998) | more than 8 years ago | (#12566279)

Meh. Dell started offering computers with builtin batteries this months ago [] . And they even include a monitor.

a nice hack (1)

Rumagent (86695) | more than 8 years ago | (#12566302)

It looks like a nice hack... But what would be really cool, was if you somehow could get the power from the monitor.

would it be better to.. (1)

martin (1336) | more than 8 years ago | (#12566312)

buy a laptop....iBook....


I'm holding out (3, Funny)

WormholeFiend (674934) | more than 8 years ago | (#12566332)

for an Apple computer that runs on human blood [] !

Oh wait...

It's also (2, Insightful)

chadseld (761331) | more than 8 years ago | (#12566354)

sans optical drive.

i could find use for it (0)

Anonymous Coward | more than 8 years ago | (#12566359)

if someone would like to download pictures from digital camera to his/her computer, then why not take that enhanced mini mac with him/her, and then power it up when there is a need for computer, and use some clever keyboard shortcut that moves pictures off of camera and voila...

there you go, at least one use for it... so no need to complain about no uses.

This is what we are doing nowadays? (0, Flamebait)

WiFireWire (772717) | more than 8 years ago | (#12566360)

C'mon, who really gives a crap that some geek put batteries in his mac mini. This article is hardly worth the kilobytes it occupies.

this would be akin to (0)

Anonymous Coward | more than 8 years ago | (#12566413)

a crack addict with a refillable bag of dope in their chest cavity... wtf?


Great, just needs a real HD now :P (1)

core (3330) | more than 8 years ago | (#12566465)

It just needs a decent internal HD now and it'll be a nice box.

Cartoon miniature golf for MacOS X: []
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