Observations on a UPS - follow up to a previous post

[Doc]

Recently I asked about suggestions regarding a UPS. I ended up
getting an 875 VA 525 Watt "Geek Squad" model from Best Buy - yeah,
yeah, everyone says Geek Squad stuff is overhyped junk, but at $69 on
sale, the price seemed right.

It seems to handle my 2 computers fine - a PIV 2.4 gig and a PIII 933
mhz sharing a monitor. With both machines and the monitor on, the
onboard readout shows them well below the unit's max capacity, drawing
about .250 - .260 kw (which I assume translates to 250 - 260 watts) ,
with an estimated run time of 9 minutes with both computers. More than
enough to get me through short hit outages with both machines running.

Interesting to note how much of a difference the monitor makes.
Without the monitor - a 17" MAG CRT, the draw for both computers
drops under 200 watts and the estimate run time for the 2 computers
goes from 9 mins to 15mins. Over 20 mins with just one computer
running but no monitor.

Since this thing has a built-in watt usage meter, any reason I
couldn't hook it up to say a refrigerator or TV to check how much
wattage they're using?

 

[Soundhaspriority]

Recently I asked about suggestions regarding a UPS. I ended up
getting an 875 VA 525 Watt "Geek Squad" model from Best Buy - yeah,
yeah, everyone says Geek Squad stuff is overhyped junk, but at $69 on
sale, the price seemed right.

It seems to handle my 2 computers fine - a PIV 2.4 gig and a PIII 933
mhz sharing a monitor. With both machines and the monitor on, the
onboard readout shows them well below the unit's max capacity, drawing
about .250 - .260 kw (which I assume translates to 250 - 260 watts) ,
with an estimated run time of 9 minutes with both computers. More than
enough to get me through short hit outages with both machines running.

Interesting to note how much of a difference the monitor makes.
Without the monitor - a 17" MAG CRT, the draw for both computers
drops under 200 watts and the estimate run time for the 2 computers
goes from 9 mins to 15mins. Over 20 mins with just one computer
running but no monitor.

Since this thing has a built-in watt usage meter, any reason I
couldn't hook it up to say a refrigerator or TV to check how much
wattage they're using?

I would avoid hookihg it up to a motor driven appliance, as these generate
powerful surges when turned off that can blow semiconductor components. The
TV is fine.

Bob Morein
Dresher, PA
(215) 646-4894

 

[William Sommerwerck]

Interesting to note how much of a difference the monitor makes.

Without the monitor -- a 17" MAG CRT, the draw for both computers
drops under 200 watts and the estimate run time for the 2 computers
goes from 9 mins to 15mins. Over 20 mins with just one computer
running but no monitor.

My experience -- at least where I live -- is that the power is off for a
fraction of a second, or hours. There's rarely anything in-between.

Than main advantage of an SPS -- again, in my area -- is protection against
the tenth-of-a-second glitches that have little or no effect on anything
else, but cause the computer to drop out. I've had as many as five or six in
a day -- imagine having to restart the computer each time, not knowing if
another might occur and slap you down again!

If you constantly save your work, a hard shutdown won't usually hurt you.
But it's always nice to have enough time -- during an extended power
outage -- to shut down the machine "rationally".

 

[Arno Wagner]

Recently I asked about suggestions regarding a UPS. I ended up
getting an 875 VA 525 Watt "Geek Squad" model from Best Buy - yeah,
yeah, everyone says Geek Squad stuff is overhyped junk, but at $69 on
sale, the price seemed right.

The price is all wrong. Nobody can build a decent product with
these specs for that price. You cannot even buy the components
needed in decent quality for that price.

It seems to handle my 2 computers fine - a PIV 2.4 gig and a PIII 933
mhz sharing a monitor. With both machines and the monitor on, the
onboard readout shows them well below the unit's max capacity, drawing
about .250 - .260 kw (which I assume translates to 250 - 260 watts) ,
with an estimated run time of 9 minutes with both computers. More than
enough to get me through short hit outages with both machines running.

And with the el-cheapo battery in there, that figure will be down to
<1 minute in no time. And you would be well advised to test the
claim. Software can be made to lie to you, you know.

Interesting to note how much of a difference the monitor makes.
Without the monitor - a 17" MAG CRT, the draw for both computers
drops under 200 watts and the estimate run time for the 2 computers
goes from 9 mins to 15mins. Over 20 mins with just one computer
running but no monitor.

Since this thing has a built-in watt usage meter, any reason I
couldn't hook it up to say a refrigerator or TV to check how much
wattage they're using?

A) the watt-meter is likely very crappy, given that a good AC
watt-meter costs more than this whole thing. They likely do a
current average and then some magic correction. Can be 50% off
or more even when used as intended. B) this device is
not intended to support motors.

Arno

 

[Doc]

The price is all wrong. Nobody can build a decent product with
these specs for that price.

Well, it was a sale price. I'm not sure that anything they sell there
is "top of the line".

And with the el-cheapo battery in there, that figure will be down to
<1 minute in no time. And you would be well advised to test the
claim. Software can be made to lie to you, you know.

I'm going by the readout on the front of the gizmo, though it does
have software that gives many of the same readouts along with some
other tasks.

A test to find out how long it will actually run the computer sounds
like a good idea.

A) the watt-meter is likely very crappy, given that a good AC
watt-meter costs more than this whole thing.

Maybe, but a lot of people seem to swear by the Kill-A-Watt meter,
which can be had all day for around $25 online, eBay etc.

 

[James Sweet]

Recently I asked about suggestions regarding a UPS. I ended up
getting an 875 VA 525 Watt "Geek Squad" model from Best Buy - yeah,
yeah, everyone says Geek Squad stuff is overhyped junk, but at $69 on
sale, the price seemed right.

It seems to handle my 2 computers fine - a PIV 2.4 gig and a PIII 933
mhz sharing a monitor. With both machines and the monitor on, the
onboard readout shows them well below the unit's max capacity, drawing
about .250 - .260 kw (which I assume translates to 250 - 260 watts) ,
with an estimated run time of 9 minutes with both computers. More than
enough to get me through short hit outages with both machines running.

Interesting to note how much of a difference the monitor makes.
Without the monitor - a 17" MAG CRT, the draw for both computers
drops under 200 watts and the estimate run time for the 2 computers
goes from 9 mins to 15mins. Over 20 mins with just one computer
running but no monitor.

Since this thing has a built-in watt usage meter, any reason I
couldn't hook it up to say a refrigerator or TV to check how much
wattage they're using?

Yeah CRT monitors take a lot of juice, it's one of the reasons flat panels
are so popular, though I still prefer a good CRT as it looks slightly better
to my eyes.

Sure you can plug in other items, though motorized appliances will probably
not particularly like the modified sine wave those things put out.

Your best bet for that is to buy a Kill A Watt or similar device, they're
only about 25 bucks and will do so much more. You get accurate measurments
of watts, volts, amps, volt-amps, power factor, and accumulated kwa and you
can plug in anything you want.

 

[James Sweet]

A test to find out how long it will actually run the computer sounds
like a good idea.

That's a good way to kill the battery, these things tend to really punish
batteries, after a few complete cycles they're often pretty well toast. You
should be fine to try it for a bit, say 5 minutes without issues.

Maybe, but a lot of people seem to swear by the Kill-A-Watt meter,
which can be had all day for around $25 online, eBay etc.

EE friend of mine compared one to a $2500 power analyzer at work, found that
the Kill A Watt performance is pretty much inline with the specs printed for
it. It's not as good as the professional equipment, but it's really very
impressive for what it is and certainly adequate for consumer use. The
wonders of modern microelectronics, it's amazing what they can do with one
inexpensive chip and a handfull of passive components. I still remember when
a pocket calculator was $300, then a few years later $50 would buy one just
as effective, and not long after that they were under $20 and those are all
more capable than large machines costing many thousands just a few decades
earlier.

 

[Arfa Daily]

Yeah CRT monitors take a lot of juice, it's one of the reasons flat panels
are so popular, though I still prefer a good CRT as it looks slightly
better to my eyes.

Sure you can plug in other items, though motorized appliances will
probably not particularly like the modified sine wave those things put
out.

Your best bet for that is to buy a Kill A Watt or similar device, they're
only about 25 bucks and will do so much more. You get accurate measurments
of watts, volts, amps, volt-amps, power factor, and accumulated kwa and
you can plug in anything you want.

But be aware that in general, these cheap 'power' meters are expecting
'traditional' sine-draw loads. I have seen wildly inaccurate standby figures
being given for equipment, by eco-campaigners that have been let loose with
one. A lot of modern equipment that makes use of switch mode power supplies,
handles standby mode by brief bursts of full draw operation. This can
confuse a simple power calculating algorithm that's expecting continuous
draw. Also, the draw by many cheapo switchers is very asymmetric and
'dirty', and may also not produce a true reading.

I wouldn't connect a UPS to a fridge. These things are notorious for pulling
a short-term startup current of tens of amps, as they get the compressor
turning over. The UPS would probably fall over before being able to supply
this, and might, as someone else suggested, even sustain damage.

Arfa

 

[Doc]

My experience -- at least where I live -- is that the power is off for a
fraction of a second, or hours. There's rarely anything in-between.

In general, I'd say that's my seat of the pants impression too, though
not always. I also notice they'll often come in clusters.

The transformer - if that's the correct term for it - big gray
basically cylindrical unit on top of a power pole - near my house blew
once. Powerful **BOOM** and a huge column of flame. Not sure what the
fuel for the flame was, do they have oil in them? Also a bit
disconcerting since anyone nearby surely would have been in jeopardy
from flaming debris.

Needless to say, power was out for a while on that one.

 

[Doc]

That's a good way to kill the battery, these things tend to really punish
batteries, after a few complete cycles they're often pretty well toast. You
should be fine to try it for a bit, say 5 minutes without issues.

Seems I've heard an occasional complete drain-down and recharge will
extend the life of a rechargeable battery, that being constantly
partially discharged and recharged is what shortens their life. Not
so? Does it depend what kind of rechargeable it is?

 

[Joseph Ashwood]

Seems I've heard an occasional complete drain-down and recharge will
extend the life of a rechargeable battery, that being constantly
partially discharged and recharged is what shortens their life. Not
so? Does it depend what kind of rechargeable it is?

It does depend on the battery. Early Lithium-Ion batteries benefitted from
the occassional full discharge, and Nickel-Metal Hydride batteries may
benefit from it. Lead-Acid batteries (like is in your car) have major issues
if they are completely drained, these are also the common battery in cheap,
well, just about everything. Newer Lithium-Ion batteries and Nickel-Metal
Hydride batteries have the controls in place so they don't benefit from a
complete drain. The Lithium-Polymer batteries that are beginning to appear
in some places do not benefit from complete drains, nor do they have
problems with overcharging, and now that they've gotten the self-ignition
problems eliminated look to replace just about everything but lead-acid.

So know your batteries, and you know the necessary behaviors, but really the
only problem ones are Lithium (non-rechargable) and Lead-Acid (damaged by
full drain).
Joe

 

[Arno Wagner]

That's a good way to kill the battery, these things tend to really punish
batteries, after a few complete cycles they're often pretty well toast. You
should be fine to try it for a bit, say 5 minutes without issues.

EE friend of mine compared one to a $2500 power analyzer at work, found that
the Kill A Watt performance is pretty much inline with the specs printed for
it. It's not as good as the professional equipment, but it's really very
impressive for what it is and certainly adequate for consumer use. The
wonders of modern microelectronics, it's amazing what they can do with one
inexpensive chip and a handfull of passive components. I still remember when
a pocket calculator was $300, then a few years later $50 would buy one just
as effective, and not long after that they were under $20 and those are all
more capable than large machines costing many thousands just a few decades
earlier.

Hmm. Interesting. I trust he did this right and tested non-ohmic
loads such as a PC PSU as well?

Arno

 

[William Sommerwerck]

Seems I've heard an occasional complete drain-down and recharge

will extend the life of a rechargeable battery, that being constantly
partially discharged and recharged is what shortens their life. Not
so? Does it depend what kind of rechargeable it is?

You're thinking of nickel-cadmium batteries. The lead-acid batteries used in
these power supplies can be crippled or destroyed by a "full" discharge. Try
to avoid it.

 

[Arno Wagner]

On Aug 12, 8:45 pm, "William Sommerwerck" <[email protected]>
wrote:

In general, I'd say that's my seat of the pants impression too, though
not always. I also notice they'll often come in clusters.

The transformer - if that's the correct term for it - big gray
basically cylindrical unit on top of a power pole - near my house blew
once.

Ugh. Putting them up for each individual hous is a very, very
historic way to do it.

Powerful **BOOM** and a huge column of flame. Not sure what the
fuel for the flame was, do they have oil in them?

Yes, for cooling. If it was an old transformer, you might have
giotten a nice load of Dioxins for free there...

Also a bit
disconcerting since anyone nearby surely would have been in jeopardy
from flaming debris.

The right way to do this is to use bigger transformesr for 10-100 houese
and to bury 3-phase AC lines. A lot more expensive, but pays off
in the long run, since you have less problems. And all these ugly
poles and transformers will vanish.

Needless to say, power was out for a while on that one.

I can believe that.

Arno

 

[William Sommerwerck]

Lead-acid batteries (like is [sic!] in your car) have major issues

if they are completely drained, these are also the common battery
in cheap, well, just about everything.

The _only_ consumer products I've owned that used lead-acid batteries were
an early Sony Discman, and two APC SPSs. They are not common in consumer
products. They provide relatively high capacity at a low cost (which is why
they're used in SPSs and UPSs), but they are too-easily damaged by a full
discarge. I accidentally ruined a $45 batter for the Sony D-T10.

 

[William Sommerwerck]

My experience -- at least where I live -- is that the power is off for a

In general, I'd say that's my seat of the pants impression too,
though not always. I also notice they'll often come in clusters.

Yes. The glitches are rarely isolated events.

Around my area, wind storms often cause sustained outages in areas where the
lines are above ground.

 

[David]

But be aware that in general, these cheap 'power' meters
are expecting
'traditional' sine-draw loads. I have seen wildly
inaccurate standby figures being given for equipment, by
eco-campaigners that have been let loose with one. A lot
of modern equipment that makes use of switch mode power
supplies, handles standby mode by brief bursts of full
draw operation. This can confuse a simple power
calculating algorithm that's expecting continuous draw.
Also, the draw by many cheapo switchers is very asymmetric
and 'dirty', and may also not produce a true reading.

I wouldn't connect a UPS to a fridge. These things are
notorious for pulling a short-term startup current of tens
of amps, as they get the compressor turning over. The UPS
would probably fall over before being able to supply this,
and might, as someone else suggested, even sustain damage.

Arfa

I have a "Kill-A-Watt" and it appears to display true RMS
for voltage and current readings. The voltage reading for a
modified sine wave from a standard UPS displays the actual
RMS voltage. I do not know what crest factor it can handle
but displays power factors of considerably less than unity
for most consumer electronics with DC rectifiers off of the
line voltage. It is a very nice unit for the price.

David

 

[Arfa Daily]

I have a "Kill-A-Watt" and it appears to display true RMS for voltage and
current readings. The voltage reading for a modified sine wave from a
standard UPS displays the actual RMS voltage. I do not know what crest
factor it can handle but displays power factors of considerably less than
unity for most consumer electronics with DC rectifiers off of the line
voltage. It is a very nice unit for the price.

David

But that's my point. You can't have a 'true' sine-based RMS figure for power
consumers that draw a pulsed current. Just because it is a sine wave that's
*available*, it doesn't mean that the load will draw anything like a
sinusoidal current, from it. The only items that will are those that are
totally 'passive' in nature, such as light bulbs. Even power supplies that
are transformer based, are likely to draw current in pulses from the
available sinusoidal supply, and switch mode power supplies, on which most
modern consumer electronics are based, most certainly won't draw a
sinusoidal current from the supply.

Arfa

 

[Scott Dorsey]

Seems I've heard an occasional complete drain-down and recharge will
extend the life of a rechargeable battery, that being constantly
partially discharged and recharged is what shortens their life. Not
so? Does it depend what kind of rechargeable it is?

It does not extend the life. Back in the seventies when NiCd packs had
memory effect, folks were recommending deep discharge. But today, you
are more likely to wreck a NiCd pack by reverse-charging a cell that way.

The cheap UPSes use gel-cells, which are gelled-electrolyte lead-acid
batteries. They are better at surviving deep discharge than NiCd packs,
but they still don't like it. Consequently, most equipment that uses
them will shut off when the battery voltage drops too low, to prevent
damage. Electronics are cheaper than batteries. Bigger UPS units use
liquid-electrolyte cells so you can check the battery condition with a
hydrometer periodically, and they also have a pulsed charging system that
prevents sulfates from building up on the plates. The Wal-Mart cheapies
probably do not.
--scott

 

[David]

But that's my point. You can't have a 'true' sine-based
RMS figure for power consumers that draw a pulsed current.
Just because it is a sine wave that's *available*, it
doesn't mean that the load will draw anything like a
sinusoidal current, from it. The only items that will are
those that are totally 'passive' in nature, such as light
bulbs. Even power supplies that are transformer based, are
likely to draw current in pulses from the available
sinusoidal supply, and switch mode power supplies, on
which most modern consumer electronics are based, most
certainly won't draw a sinusoidal current from the supply.

Arfa

Arfa,
I know that the current draw on these things is anything but
sinusoidal. My point was that the "Kill-A-Watt" seems to
actually compute the RMS value for that complex current
waveform as well as non-sinusoidal voltage waveforms.

David