Do-it-yourself UPS

Giampiero writes "Over at dansdata.com some guy named Dan creates a UPS out of some spare parts. To sum it up, "if you're looking for an industrial-capacity UPS solution, and don't like the prices of the off-the-peg options, it might be easier than you think to roll your own."" Of course you can mentally substitute U.S. 110 volts for Australian 220 volts wherever necessary...

Comments

Why convert DC to AC to DC?

[cyberformer]

A major part of the description on the site (and the cost of a "real" UPS) is how to convert the DC output of a UPS to the AC power required by most PCs.

Of course, PCs don't actually use AC power: there's a big box in the back that converts all the AC input back to DC. So why not save some money and bypass this, by running the PC straight off the battery (like a laptop)?

Re:Why convert DC to AC to DC?

[steveha]

I have, for years, wished for a DC input on the PC's power supply, and a standard for UPSes that would plug in to that DC input.

Taking DC, converting to AC so the PC power supply is happy, then the power supply converts to DC... it would be nice if it could just be DC all the way.

The problem is that your monitor, modem, etc. all expect AC power. It's easiest just to make a UPS that provides standard AC power, and plug everything in.

Someday, I think we will have "smart" plugs. Wall power outlets will not be live by default; they will only serve power when a proper coded request goes in over a smart plug. The device will be able to tell the wall outlet what kind of power it wants, and the outlet will be able to tell the device what kinds of power it can offer. Then little kids will stick butter knives into wall outlets and not get fried; PCs and monitors will ask for +5 and +12 volts DC and get it; and UPSes will be able to feed +5 and +12 volts DC to those PCs and monitors.

Actually, if you have the complicated smart power system I envision, there will probably be a UPS integral to the system. When your home loses power, the smart power system would broadcast a "power interrupted" signal and devices like your refrigerator and your laser printer will power themselves down; your PC will run for about 5 minutes and then power itself down (unless you are there and override it) and medical devices will run indefinitely. Maybe only the DC devices in your home will be on the UPS by default?

steveha