Tuesday, 24 May 2011

Home Server UPS

Recently I’ve been wanting to have some kind of power back system for my home server setup. Just a little project of mine. Though it would be cool to have in-case of an unexpected power failure while doing data critical stuff. Also I use the server to record CCTV images from a camera mounted at the back of the house, so having a power back-up system is a good idea. Rather than going the usual route of using a standard mains voltage UPS converting AC-DC-AC then back to DC from the server PSU. I thought I'd get and try out the picoUPS and a picoPSU from minibox.com. Since my server uses a low power Intel Atom mini ITX board i thought it would maybe save some power, because no power conversion would be needed.

Here's the picoUPS-100 from LinITX.com and a picoPSU-80-WI off ebay. From an Mini-Box authorized reseller!  (I colour coded the spade connectors with red and black maker pens)

The picoUPS-100 is a miniature UPS with an on-board lead acid battery charger. And will automatically switch to battery when power from the input is lost. But in order to charge the battery properly the picoUPS needs 15-18v. So I used a 16V 4A laptop power brick from an old Sony viao laptop. While in normal operation the Pico UPS will output the same voltage as supplied, In my case 16V. Then when the power fails on the input the pico UPS switches to the battery dropping the voltage to 12V. Because of this a picoPSU with a wide input voltage must be used. As the standard picoPSU (80w and 120w) runs on 12v DC only so can not be used. So I used a picoPSU-80-WI that will run on anything from 12v to 32v. I also added some PCB feet to the UPS board so it can be mounted on something in future. For my backup battery I’m using a new Yuasa 12v 12Ah SLA off ebay.

Here's my mini itx home server setup:

(In case you're wondering its a Intel Atom D410PT, 512Mb RAM and 250GB HDD)


I removed the standard ATX PSU from the case. (It was located at the front of the case, I forgot to take pictures of it!.)

Then installed the PicoPSU-80-WI.


The cables that come with the picoUPS had to be modified to suit my needs. I added a 2.5mm DC power connector and swapped the spade connectors for some wider ones as the ones supplied would not fit the battery terminals. 


Now here’s the complete setup running, with the picoUPS, battery, 16v 4A PSU and the home server. (Note all the old stickers on the shelf! It used to be part of a wardrobe, from when I was 10 years old. LOL)

I tested how long the battery would last during a loss of power. It kept the system up and running for nearly 4 hours! Quite amazing! I kept an eye on the battery voltage to make sure that it doesn't go below 12v. While running on battery the voltage drops slowly from around 12.60v to 11.80v. Over the 4 hours that I tested, my battery voltage got to 12.32v before I restored power to the system. So it has the potential to run for longer. The picoPSU does not have under voltage shut down so the lowest voltage i would let it run to would be 11.90v. In a real power cut, I should be able to shut down the server before the battery voltage gets too low. So there you have it my UPS project.

More information about the picoUPS:

Other poeple using the picoUPS:

1 comment:

  1. Interesting. I happening to be building something similar (albeit a lot larger, with four NP12-12S's).

    I would put an ATO inline fuse *right* next to the positive terminal of the battery if I were you. If something metal were to fall on your UPS PCB, or it were to develop a fault, you have an instant fire.