UPS for Computers

I just have a couple of questions about the UPS devices you can get
for your computer.

How do you know how much power your computer and it's peripherals use?
And how do you know what it uses on average? How do you go about
calculating or measuring the typical power consumption of your system
so you have a better idea of what capacity UPS device you need?

I also wondered if it is possible to connect an external battery to a
UPS device in some way to boost the amount of back up time you have?
Do any of the devices on the market today allow external batteries to
be added? I think it would be quite useful if you could add a small
additional battery if your current UPS isn't giving you enough back up
time.

My system I would definitely want the computer and monitor as well as
the ADSL/Router to be permanently connected to the UPS. I would also
like the other device to be connected to like the printer and scanner
even though these are not as critical. Do most UPS device today give
you lots of different connection options e.g. computer power lead, 3
pin plug (uk) etc? As far as my ADSL/router is concerned I would never
want the power to go out on that, I would always want it to be
powered.

Cheers for your advice.

John

 

Get a portable watt-meter - like the Kill-A Watz or whatever.

The old Powerware Prestige EXT allows for external battery. They are
"obsolete" now, but available on the surplus market. The EXT runs60
volts while the standard unit ran 48.

I run my router and cable modem on a small UPS (350 va) and my main
system on a 600va Prestige. This is a dual conversion system so I get
100% clean power all the time.

 

The best way to is to measure. As the other fellow said, a kill-a-watt
meter isn't terribly expensive. Other people have measured typical
computers, monitors, printers, etc. and posted their results on this
and other newsgroups as well as websites. A little web searching
should yield some results.

Yes, it's possible but it works best if the UPS is designed to have
external batteries. Many of them do, though not many of the small
consumer versions.

Most of these units have a number of AC outlets and you can add
power strips if you need more. It's typical for people to power
their entire system off their UPS, laser printers excluded.

I haven't heard of any that have anything but ordinary AC outlets
but I imagine that with a little tinkering you could add DC from
the battery terminals inside. The style of outlet is usually the
same as those used in your country. A French UPS will not have the
same outlets as an American version. This is not usually a problem
because few people buy these internationally.

Anthony

 

UPS are basically to give time to cover minor power burps and time for
orderly shutdown, not extended operations.

small consumer units will overheat on external batteries, buy only a
unit with built in external battery capacity to avoid the overheat
issues.

UPS are generally too small to run printers, and printing may induce
transients that cause computer problems, your better off to at minimum
have them on seperate UPS.

If operations are that critical consider a auto backup generator
running on natural gas or propane for essentially indefinite operation
of most of your homes systems

 

You can measure it or estimate it. Some products especially monitors tell you
how much power they consume.

What you need to be aware of is that PCs use more power on start-up, although a
good UPS may have an allowance for this.

It's wise to be slightly generous in your UPS sizing btw. You never know what
you might want to add later.

Graham

 

Not sure

But how do you estimate the MPG of an auto or truck??

USE YOU FREEKIN HEAD

SAUL

 

Inkjets are OK on a UPS if necessary, but NEVER a laser. Any dual
conversion UPS will work almost infinitely if enough DC power is
available. They are DESIGNED to run full time. Only caveat is you will
likely require an external charger to handle the extended run
batteries if the unit was not built as extended run.
I like the idea of a small IC engine powered generator for extended
run, like the old BEST UBS system.

 

They tell you the MAXIMUM they will draw, not necessarily the real
running power. Many good UPS units will actually TELL you how much
load they are running (as a percentage of full load)
20% on a 600va unit is 120 va.

They use only a moderately greater amount on startup - they use more
when accessing hard drives or cds and more yet when writing to them.

NEVER try to scrimp and use a marginal device. Slightly oversized buys
you a lot of reliability.

 

Lower end UPS TODAY are built on the cheap.

If you KNOW in advance like the manufacturer does the battery run time
at full load is 15 minutes why build the hardware to run continiously
for hours? by that time the battery will be long dead and besides you
sell the super duper 5 hour model for such applications for 5 grand.

so the design the 15 minute full load to overheat at ull load after 30
minutes knowing it will never happen.

Incidently I found this out by the school of hard knocks

Few UPSs today are designed for multi hour operation at full load,
like printers etc. If you need that buy a generator remembering
batteries ALL go bad over time. within 3 years realize run time will
be about half, because of battery aging...

 

Thanks for all the advice.

I actually already had a current meter that you plug in so I have
pulled it out the back of the wardrobe and tested it on my system and
was quite surprised by the results.

My system appears to only be using around 100 watts of power when
switched on, give or take a fluctuation of 5 watts.

I'm pretty sure that the power supply in my system was something like
380 or 420 watts. I know it was higher than the power supply I have
had in the past for previous systems. My system does have quite a few
devices and drives in it so it was a surprised it is only drawing
100w.

I have yet to test the power draw of the ADSL/router on it's own.

As far as a ups device overheating is concerned, when these devices
are connected to your computers it is constantly powered from the
mains power supply to keep the battery topped up right?

I am just trying to understand how it would overheat if it was still
constantly connected to the mains power but with a 12v deep cycle
battery in between?

So you would have the mains keeping the 12v deep cycle battery topped
up, and that would then be going via a 12/240v inverter providing say
around 150w of power (which would be more than enough to cover my
system) which would keep the UPS topped up and the computer in
business.

The only time the battery from the UPS would start to drain would be
after the deep cycle battery had run out during a power cut. If I had
a deep cycle battery with a capacity of about 100 amp hours, that
would provide quite a few hours of use at 100 watts consumption before
it would exhausts wouldn't it? And by that time the electric may be
back on anyway.

Can anyone see any flaws to this type of setup?

John

 

Which does NOT change the FACT that a dual conversion UPS of ANY
stripe is built to work 24/7, 365 days a year if enough DC power is
available.

 

If it is not a dual conversion UPS, the computer runs off mains power
untill the mains power fails. The inverter then takes over. A dual
conversion UPS is essentially a large battery charger, a battery, and
an inverter.
There are dual conversion, line interactive, and standby UPS systems.

 

Most small consumer UPS units are strictly standby. The inverter
doesn't activate until you lose power and, as has been stated
elsewhere, they often skimp on cooling.

Anthony

 

That *might* be the original intention of the engineers, but, by the
time the accountants and marketing people have had their say, then
what the customer *actually* ends up with isn't capable by any stretch
of the imagination of 24/7 365 operation.

Heck some of them, and I'm talking about big names here, even after
many years experience in the field don't even know how to properly
float charge the batteries they fit in multi thousand dollar UPS's.



--

 

You do not understand. A DUAL CONVERSION UPS DOES run 24/7, 365 days
in NORMAL USE. The inverter runs ALL THE TIME, supplying the FULL
LOAD.

 

Yes I do COMPLETELY understand the concept of a dual conversion UPS
and I stand by my statement.

The lack of fault tolerant design such as redundant cooling fans and
restrictive particle filtration is a continuing design error in a
significant number of dual conversion UPS's Site the equipment in an
air conditioned environment and you might get away with it for a
couple of years, fit it in the real dusty grimy world especially with
temperatures approaching the upper end of its declared operating
regime and you are extremely lucky to get much more than 365 days use.




--

 

The same goes for ANY equipment. Abuse it and it WILL FAIL.

 

I have one of those - a low-end APS brand. If the mains power
goes off, there is an audible "click," which I guess is a relay
switching between the mains feed-though, and the inverter.

There doesn't seem to be any provision for cooling at all.

It's really just to get through very brief (say, two second)
dips, and to give time to shut down, if the mains stays off
longer than that.

 

I'm assuming you mean APC, not APS, and you are right, their low end
stuff SUCKS. Their midline stuff isn't much better from my 20+ years
experience.