[CentOS] Power-outage

[Jason Pyeron]

> -----Original Message-----
> From: centos-bounces at centos.org 
> [mailto:centos-bounces at centos.org] On Behalf Of Marko Vojinovic
> Sent: Saturday, July 02, 2011 13:58
> To: CentOS mailing list
> Subject: Re: [CentOS] Power-outage
> 
> On Saturday 02 July 2011 18:21:27 Jason Pyeron wrote:
> > > > > But surely computers actually use DC, so couldn't my 
> > > > > torch-battery device just supply the PC components directly?
> > > > 
> > > > A PC uses several *different* DC voltages: +12, +5, +3.3, and 
> > > > several others and they need to be *precise*.  Some of 
> these are 
> > > > not an exact multiples of the standard 1.5V Carbon-Zinc cells 
> > > > typicaly used in torch batteries.
> > > 
> > > I wonder, how is this issue solved in laptops? They use 
> only one DC 
> > > battery, typically with a single voltage output, AFAIK.
> > 
> > (sorry ctrl-enter sends...)
> > 
> > Laptops, google mother boards, etc have power supply 
> circuits on board.
> > Remember that a switching powersupply taking AC still has dc to dc 
> > converters in it after the conditioning stage.
> 
> So couldn't the OP then plug a battery "in between" (I'm 
> talking in principle here, not realistically) --- after the 
> AC-to-DC stage but before the "conditioning" stage?
> 
> If a laptop can have several *different* and *precise* 
> voltages from a single DC battery, why the desktop cannot?
> 
> I am not saying that it would be easy or cheap, just that the 

But the OP wanted cheap. Nor would it be easy.

> above "different voltages" argument seems false from my POV. 
> If a laptop can be battery- powered, so can a desktop (given 
> that you have all the hardware to implement it). You don't 

There is lies the rub, it is easier and cheaper to buy one, but it is even
cheaper and easier to buy an UPS. The UPS comes with insurance too.

> need to tweak the motherboard, just the PSU. It's routinely 
> done in laptops, so it doesn't seem to be rocket-science or 
> something too expensive. I wonder why aren't there any 
> desktops on the market with same technology?

Because, it is more expensive in a world where 110 or 220 AC is standard. Our
server room has DC supply for critical infrastructure, but that costs more to
maintain and install. The battery room requires fire and enviromental equipment
and configuration, the personnel who enter the room require certification and
training on how to handle acid, hydrogen, fires, spills, etc. The electrical
infrastructure required extra time and money to install because the local code
did not have rules for high amprage extra low voltace (50V<low voltage<1kV) DC
circuits. There are extra conduits installed, most licensed electrictions are
not prepared to handle DC, so those who do cost more.........

I think you get the point.

> 
> I'm using an UPS for my desktop system, but I don't need it 
> for the laptop. If the AC power drops, even for a moment, the 

They are also low wattage, http://www.indocomp.com/ind-ups200-atx-spec.html,
http://www.eurasiapower.com/power_supply_eu_eUPS-350.asp,
http://www.apollo.com.tw/products_data.html

> laptop battery will kick in and sustain the machine. I just 
> think that the same thing can be implemented for the desktop 
> too. If I understood the OP correctly... ;-)
> 

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