Can I run a computer using DC power?

Question

I always thought that using a conventional UPS with a PC is highly inefficient. Power goes from AC -> DC -> AC in UPS and then AC -> DC in PC SMPS. Since PC works only with DC (12, 5 and 3 volts) It should be possible to convert AC -> DC once and use that to charge SLA battery and drive a PC.

Sure enough there are solutions for this. For example PicoUPS-100. These are designed for embedded PC, but I see no reason why such a device cannot be used for home PC also. Place where I live has frequent power outage and if I can hookup couple of battery with such a system it would give me long battery backup time with minimal cost if I use a power efficient PC.

Does any one have any experience with such systems for a mainstream (home) PC.

Solution 1

Google does exactly that! They do not have the UPS in the datacenter, they have the UPS on the machine itself, and feed DC to the mainboard. And they are only feeding 12V, as it is more energy efficient than lower voltages.

Solution 2

Make sure you take a look at Mini-box.com's selection of DC-DC ATX PSUs.

EDIT: I see that your original link is from there! :-) I will actually be buying one of these this summer, as I notice that their selection has increased to include some ranged input voltage PSUs. Look at the M4 enclosure for mounting in a more traditional style. Then, you can run wires direct to your box. Visit your local hardware store for some good insulated options. Or, hack a cable to a power supply that you don't use any more, etc.

Solution 3

I've thought about this for some time, you should look into Zener Diodes, 12V car batteries (SLA) and home made battery chargers. Cheap and interesting.

I've seen mission critical data centers running off 24 12V in parallel and serial (several Amper-Hours at 24V) transformed to 220V.

Comments

[Rajkumar S]

Yes! I am aware of it. Google server actually convinced me that this is viable, but here I am looking for some info about the same technology for home users.

[voyager]

Talk about indirection!

[Peter Mortensen]

The Zener diode in those battery chargers is used as a voltage reference. The constant voltage is then used with a potentiometer for manual adjustment of the set value for the battery voltage.

[Ken Sharp]

Link is dead 404