UPS Batteries (again)

Mon Dec 22 15:19:36 PST 2003

Quoting Wolfgang S. Rupprecht (wolfgang+gnus-baylisa at dailyplanet.dontspam.wsrcc.com):
> 
> jyetter at bluedogs.org (Joseph E. Yetter, Jr.) writes:
> > BTW: I've put together my house's 24v solar system, with both
> > lead-acid and gel-cells. 
> 
> Have you found a good high-efficiency 24vdc-input ATX power supply yet
> or ar you going to run your computers from 120vac?  
> 
> I've been hoping to find a good power supply that would allow me to
> run an ATX computer directly from a pile of lead acid cells kept in
> the crawl space.  The only one's I've been able to find are no-name
> brands that when they bother to tell you the efficiency at all, it is
> something downright awful like 60%-80%.

Not sure what the power supply would be doing then...

ATX outputs, AFAIR, +/- 12VDC and 5VDC.
With DC input it's just a step up/step down conversion.

My laptop takes 20V (I believe it's DC).

There are many ways to step down 24VDC and 48VDC, improved lots
even in the last couple years.

The big part of switching power supplies it dealing with the 240/120VAC
input and getting the voltages needed.

While graphics (esp) tend to need bursts of power which may not be
available from modest batteries, capacitors can provide that.  More
an issue with a car and/or car battery than a solar setup.

That said, best value for energy usage is laptops (and LCD screens).

Putting up solar to save money and using a 21" CRT and old 500MB
drives (and then perhaps paying to keep the room cool) is sort of
at odds with itself.  That said, I do have computers from the dark
ages (just not generally on).

60-80% sounds like typical inverter efficiencies, and your not inverting.