Pico 12V power supplies

[Red Squirrel]

I just ran across these:

http://www.ncix.com/products/index.php?minorcatid=1066&subminorcatid=369

They look rather interesting. The attractive point is that they take a 12V DC input. That's one conversion less to do. Could I run these straight off a 12V battery bank that is hooked up to a rectifier? I think it would be neat to convert all my server equipment to use these PSUs and just run straight off batteries. Would give better uptime during power outages, for cheaper, and it's more efficient.

Only thing is 200W seems to be the highest they go. Enough for a lot of machines though, but not all.

 

[Magic Carpet]

If you have a battery bank, then I see why not. Have you worked out the costs?

 

[Red Squirrel]

Quickly worked them out. Basically a decent sized UPS is in the thousands, while I could buy a couple high quality batteries for half that, then just need to find a rectifier that can handle the load. The rectifier is the tricky part, I have not found any sites that actually sell them, so no idea how much money I'm looking at.

This is just some fun thoughts, I don't have any money now to do any of this.

 

[natto fire]

These would have come in handy at the last place I lived with their array of solar panels. Why not simply get an off the shelf battery charger for rectifying AC? I would be more worried about the fact that the PSU says it only accepts 12v and perfectly healthy battery will output 12.6, and you will be charging at between 13 and 14 volts.

So much for saving conversion losses if you are rectifying your AC to charge DC batteries that then need their output filtered to 12v nominal. Cool design on the PSUs, though.

 

[fffblackmage]

^I was taking a quick look at some of the Pico PSUs and there are "wide input" models. Basically, they can take a wider range of DC voltage input (like 12-25Vdc). That sounds pretty good if you have to deal with battery voltage and the charging voltage... etc.

http://www.logicsupply.com/products/pico120wi_25

 

[aigomorla]

they are used in cars too.. for the carPC.

I played with one, and it works OK on a low power system.
Basically a i3 with a itx board in short with no dedicated GPU, or something which draws less.

Not recommended if ur going to add a dedicated gpu.

 

[mindless1]

It is not necessarily true that just because they do 12V DC input, that any old ~ 12V source means one less conversion. Take a 12V SLA battery for example, it is not 12.0V. During charging it's at 13.n V, above the 10% spec. During discharge it depends on the rate, 12.6V nominal and dropping as battery discharges or at higher discharge rates.

If on the other hand you have a switching PSU suppling 12.0V (or very close), THEN there is one less conversion to do. As someone already pointed out, some do have wide input range and regulate the 12V output so that's not a problem or anything, I just wanted to be clear.

I don't understand what is meant by hooking a 12V battery up to a rectifier? You mean the classic electronics definition which tends to mean a diode to prevent reverse current? Why would you need this since battery would always be higher than what is downstream, or the power supply itself should not be feeding back into it.

Do you mean a rectifier, or do you mean a 12VDC to 110VAC inverter?

If you really mean a rectifier, describe the kind of circuit you want and the current it needs to handle and I can figure something out. In its most basic form all you need is a single schottky diode. Throwing around random numbers since the largest Pico has 200W peak output, 200W/12V = 17A. Suppose it's only 70% efficient though probably higher but margin is good, that's 17A/.7= 24A

There are some rated for 25A, but just to give a bit more margin I ignored everything at Digikey that's 25A or lower and not through-hold type so this came up:

http://search.digikey.com/us/en/products/65PQ015PBF/65PQ015PBF-ND/812759

or there are some surplus options,
http://www.allelectronics.com/make-a-store/item/STPS30L40CW/SCHOTTKY-DIODE-40V-30A/1.html
http://www.bgmicro.com/DIOMBR3035PT.aspx

Keep in mind these are rated for the current they are when mounted on an appropriate heatsink.

You can usually salvage one (or more) yourself out of an old failed ATX12V power supply, on the heatsink nearer the output wiring harness.

 

[Metaluna]

I just ran across these:

http://www.ncix.com/products/index.php?minorcatid=1066&subminorcatid=369

They look rather interesting. The attractive point is that they take a 12V DC input. That's one conversion less to do.

And the downside is...there's one conversion less to do. The problem is that a lot of the 12V power bricks that these things need to run off of have lousy regulation and efficiency compared to a decent ATX PSU, and that gets passed through directly to the load with no filtering. The Wide Input models are forced to regulate all the rails, so the 12V output is much cleaner. Unfortunately the wide-input models only go up to 80W or so.

I do like the PicoPSUs (I'm using a WI 80W on my homebrew miniITX router box), but do be aware that you need to take full responsibility for providing a clean 12V rail if you use one of the 12V models.

By the way, if you check mini-box.com, which I think is the OEM of the PicoPSU, they also have various types of UPS battery controller boards that might help with your application.