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?

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".

In comp.sys.ibm.pc.hardware.misc Doc wrote:
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

On Aug 12, 9:07 pm, Arno Wagner wrote:

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".

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.


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.



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.


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.

"Doc" wrote in message
ups.com...
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.

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.

"James Sweet" wrote in message
news:ehPvi.2400$jy5.785@trnddc07...

"Doc" wrote in message
ups.com...
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.


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

On Aug 12, 8:45 pm, "William Sommerwerck"
wrote:

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.

On Aug 12, 10:24 pm, "James Sweet" wrote:
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.


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?

"Doc" wrote in message
oups.com...
On Aug 12, 10:24 pm, "James Sweet" wrote:
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.


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

In comp.sys.ibm.pc.hardware.misc James Sweet wrote:


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.

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

Arno

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.

In comp.sys.ibm.pc.hardware.misc Doc wrote:
On Aug 12, 8:45 pm, "William Sommerwerck"
wrote:

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.

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

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.

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.

Yes. The glitches are rarely isolated events.

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

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

"David" wrote in message
et...

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


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

Doc wrote:
On Aug 12, 10:24 pm, "James Sweet" wrote:
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.

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

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"Arfa Daily" wrote in message
...

"David" wrote in message
et...

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


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

Arfa Daily wrote:

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


ICs to do the true RMS conversion are dirt cheap these days.


http://www.analog.com/library/analogDialogue/archives/34-01/rmsarticle/index.html

http://www.analog.com/en/subCat/0,2879,773%255F866%255F0%255F%255F0%255F,00.html
--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

"David" wrote in message
et

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.

It is speced to deliver true RMS readings. It will also display power
factor.

I do not know what crest factor it
can handle

Can't find it in the manufacturer's detailed specs.

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.

Agreed.

On Mon, 13 Aug 2007 04:42:02 -0700, "William Sommerwerck"
wrote:

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.



Practically all consumer grade UPS use lead-acid batteries.
Other common items using lead-acid batteries are some of the
handheld halogen spotlight (flashlights), and automotive
portable power station "thing-a-majigs" like those that can
jump a car or have a flashlight/pump/inverter. A few
transportation devices have them also like a kid's motorized
big-wheels or skateboard or motorized bike, etc.

Any decently designed UPS will cut off power before the lead
acide battery is drained to a critical level, although it is
still much harder on the battery to drain to any significant
extent, a large % of total capacity instead of the UPS
turning off as soon as possible.

On 13 Aug 2007 01:07:28 GMT, Arno Wagner
wrote:

In comp.sys.ibm.pc.hardware.misc Doc wrote:
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.


Depending on your definition of "decent", this may be true,
but it's going to be roughly equivalent to what you'd buy
from APC as a 500VA for about $50 so if that's what the
budget allows, it's not an exceptionally low price (also
considering you can sometimes get the APC discounted or with
rebate putting it closer to $20-30 than to $50.


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.

There's no reason to belive the battery is especially cheap,
it's going to be a standard lead-acid which is quite a
mature technology today, a commodity item essentially and
all that's really at question is whether the manufacturer
conservatively rated the unit or if it's unlikely to meet
the specs due to design budget constructions. Either way,
it's probably $70-100 worth of UPS, it will likely do as
well as anything else available for the same price.

If one were to pay = 2X as much, naturally the expectation
would be it's either fancier or higher capacity or an online
type, etc, but there is no expectation the battery is
inherantly any higher quality per se, though probably higher
capacity due to being a larger size or a series of two
batteries.

"James Sweet" wrote ...
"Doc" wrote...
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.

Agree completely. They are great when used with the regular
sine-wave mains power grid. However note that many have
been fried beyond repair when used with any kind of square-
wave source: inverter, UPS, etc. even "stepped sine" waveforms.

The problem appears to be the capacitive voltage divider used
to power the Kill-A-Watt electronics. The high frequency harmonics
deliver way too much power to the shunt regulator through the
capacitor and something fries.

Doc wrote:
"William Sommerwerck" wrote:

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.

About 30 years ago a friend of mine was in a neighborhood where
multiple houses were supplied from one undersized transformer, and
the power company just ignored all requests to replace it. The
residents got together, and all turned on air-conditioners, ovens,
whatever, and then went outside to watch the transformer blow. It
did, and the scheme produced a new proper sized transformer.

--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
http://cbfalconer.home.att.net



--
Posted via a free Usenet account from http://www.teranews.com

"David" wrote in message
. net...

"Arfa Daily" wrote in message
...

"David" wrote in message
et...

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


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


OK. I'm not sure that 'RMS' is the right term to attach to any value derived
from a ragged-arsed waveform, as it is a mathematical function normally
associated with symetrical waveforms, which the draw by a SMPS may very well
not be, but I see what you're saying.

What I am trying to say is that a chip which is designed to produce an RMS
reading from a sine wave, may well produce a meaningful figure from a
non-sinusoidal waveform also, but *only* if it is still symetrical.

Arfa

Doc wrote:
On Aug 12, 8:45 pm, "William Sommerwerck"
wrote:

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.

TRMOAS (that reminds me of a story)...

Years ago, when Atari ST computers were common, friends of mine lived in
and old house with just such a transformer on the adjacent pole.
Buddy had been trying for ages to get his girlfriend to start learning
to use the computer, but she was always afraid she'd "break something".

Finally one day, he convinced her to sit down and give it a try. She
took a deep breath, put her hands on the keyboard... as the room was lit
up by a brilliant flash through the window, shaken by a magnificent
**BOOM!**, and the computer screen went black.

Poor girl was in a complete panic, she was SURE it was her fault...

As it turned out, a drunk speeding down the road outside in his van had
gone THROUGH two nearby power poles and finally stopped just shy of
hitting a third; the first impact brought the lines down and was
sufficient to explode the transformer just outside their window.

....took her years to ever touch a computer again

Arfa Daily wrote:

.... snip ...

OK. I'm not sure that 'RMS' is the right term to attach to any
value derived from a ragged-arsed waveform, as it is a mathematical
function normally associated with symetrical waveforms, which the
draw by a SMPS may very well not be, but I see what you're saying.

What I am trying to say is that a chip which is designed to produce
an RMS reading from a sine wave, may well produce a meaningful
figure from a non-sinusoidal waveform also, but *only* if it is
still symetrical.

Oh? Try a square wave, for example. Nice and symetrical. You are
over-simplifying.

--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
http://cbfalconer.home.att.net



--
Posted via a free Usenet account from http://www.teranews.com

"Richard Crowley" wrote in message

"James Sweet" wrote ...
"Doc" wrote...
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.

Yup. I logged lots of hours on mechanical calculators, Wang shared-logic
desk calculators, and the HP35.

Agree completely. They are great when used with the
regular sine-wave mains power grid. However note that
many have been fried beyond repair when used with any kind of
square- wave source: inverter, UPS, etc. even "stepped sine"
waveforms.

News to me. I've used mine with UPSs, but the application was not long-term
use.

The problem appears to be the capacitive voltage divider
used to power the Kill-A-Watt electronics. The high frequency
harmonics deliver way too much power to the shunt
regulator through the capacitor and something fries.

You're aware that capacitive voltage dividers have flat frequency response,
right?

"Arny Krueger" wrote ...
You're aware that capacitive voltage dividers have flat frequency
response, right?

Perhaps you are not aware that many inexpensive consumer
mains power supplies use a capacitor rather than a resistor
as the series element of a shunt-regulated power supply.

The circuit is essentially a high-pass circuit and very much has
a rising response.

"Richard Crowley" wrote in message
...
"Arny Krueger" wrote ...
You're aware that capacitive voltage dividers have flat
frequency response, right?

Perhaps you are not aware that many inexpensive consumer
mains power supplies use a capacitor rather than a
resistor
as the series element of a shunt-regulated power supply.

The circuit is essentially a high-pass circuit and very
much has
a rising response.
Then it is not a capacitive voltage divider. The better
designs have a series and shunt capacitor and a small
resistor before the rectifier. This arrangement does have a
flat(er) frequency response. I may take my Kill-A-Watt apart
to see what they used in the design.

David

You're aware that capacitive voltage dividers have flat
frequency response, right?

Perhaps you are not aware that many inexpensive consumer
mains power supplies use a capacitor rather than a resistor
as the series element of a shunt-regulated power supply.

The circuit is essentially a high-pass circuit and very much
has a rising response.

I feel obliged to side with Arny. In the context of the original
description, it appeared as if the capacitive voltage divider was used to
drop the line voltage (as opposed to using a transformer). Putting a
capacitor in a shunt regulator is hardly the same thing.

Doc wrote:
On Aug 12, 8:45 pm, "William Sommerwerck"
wrote:

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.


Yes that transformer on top of the pole is what blew. The fuel was the
oil that acted as a dielectric insulator and heat dissipator. Older
versions have the liquid filled with PCBs (polybrominated biphenyls).
That stuff is quite hazardous.
FK

Doc wrote:
On Aug 12, 10:24 pm, "James Sweet" wrote:
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.


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?


The ones with big "memory" problems were the generally no longer used
NiCad cells. They tended to lose capacity if not fully discharged now
and then.
FK

On 8/13/2007, Arfa Daily posted this:
"David" wrote in message
. net...

"Arfa Daily" wrote in message
...

"David" wrote in message
et...

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


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


OK. I'm not sure that 'RMS' is the right term to attach to any value derived
from a ragged-arsed waveform, as it is a mathematical function normally
associated with symetrical waveforms, which the draw by a SMPS may very well
not be, but I see what you're saying.

What I am trying to say is that a chip which is designed to produce an RMS
reading from a sine wave, may well produce a meaningful figure from a
non-sinusoidal waveform also, but *only* if it is still symetrical.

Arfa

RMS is defined & well-behaved for *any* wave form.

It is, as its name implies, just the square root of the integral over a
time interval of V-squared, divided by the integration time.

In an attempt at ASCII math notation: sqrt [(1/T)*{integral from t0 to
t0 + T} V^2 dt]

It works best (esthetically) if T is very long, or at least a whole
number of cycles of the waveform.

What is *not* well-behaved for unusual waveforms is the shortcut
formula giving RMS as a factor times the magnitude of the peak voltage.
I forget: is it Vmax*[sqrt(2)]/2 ? Whatever the correct shortcut is, it
is only correct for a sine wave (or a rectified sinewave, as is
mathematically obvious) :-) )

--
Gene E. Bloch (Gino)
letters617blochg3251
(replace the numbers by "at" and "dotcom")

"Gene E. Bloch" wrote in message
...
On 8/13/2007, Arfa Daily posted this:
"David" wrote in message
. net...

"Arfa Daily" wrote in message
...

"David" wrote in message
et...

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


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


OK. I'm not sure that 'RMS' is the right term to attach to any value
derived from a ragged-arsed waveform, as it is a mathematical function
normally associated with symetrical waveforms, which the draw by a SMPS
may very well not be, but I see what you're saying.

What I am trying to say is that a chip which is designed to produce an
RMS reading from a sine wave, may well produce a meaningful figure from a
non-sinusoidal waveform also, but *only* if it is still symetrical.

Arfa

RMS is defined & well-behaved for *any* wave form.

It is, as its name implies, just the square root of the integral over a
time interval of V-squared, divided by the integration time.

In an attempt at ASCII math notation: sqrt [(1/T)*{integral from t0 to t0
+ T} V^2 dt]

It works best (esthetically) if T is very long, or at least a whole number
of cycles of the waveform.

What is *not* well-behaved for unusual waveforms is the shortcut formula
giving RMS as a factor times the magnitude of the peak voltage. I forget:
is it Vmax*[sqrt(2)]/2 ? Whatever the correct shortcut is, it is only
correct for a sine wave (or a rectified sinewave, as is mathematically
obvious) :-) )


I bow to your knowledge on this one, as you clearly have a better grasp of
the math involved than I. So are you saying that a meter that measures
*true* RMS anything - power, current, volts - will do so correctly even if
the waveform is asymmetric about the zero point ? I always believed ( was
taught ? - college seems so long ago now ... ) that even distribution about
the zero point, was a requirement for an accurate representation of an RMS
value ??

Arfa
--
Gene E. Bloch (Gino)
letters617blochg3251
(replace the numbers by "at" and "dotcom")

So are you saying that a meter that measures *true* RMS
anything -- power, current, volts -- will do so correctly even
if the waveform is asymmetric about the zero point? I always
believed that an even distribution about the zero point was a
requirement for an accurate representation of an RMS value.

The RMS value of a waveform has nothing to do with the shape or symmetry of
the waveform.

Assuming the meter is correctly designed, yes. RMS has a clear, specific
definition, and if the measurement is correctly implemented, the reading
will be correct.

Two qualifications... If the waveform is non-periodic, the measured RMS
value will vary according to the sample period. Also, if the waveform
includes a DC component, and the meter blocks it with a capacitor, then the
RMS reading will not include the DC component.

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.



I read recently that the memory effect "myth" was created due to cheap
chargers overcharging the batteries unless they were first fully discharged.
A decent intelligent charger should prevent this, and batteries have in
theory improved as well.

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?



Yes, of course, pure resistive loads can be measured just fine with a
multimeter. We were interested primarily in using it to measure discharge
lamp systems in which the power factor and current waveforms can be all over
the place and vary greatly with the state and condition of the lamp. If the
meter wasn't able to handle odd waveforms, the power factor measurement
function would be useless, but it works pretty well, accuracy is within
about 2% on the sample tested.

"Richard Crowley" wrote in message
...
"James Sweet" wrote ...
"Doc" wrote...
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.

Agree completely. They are great when used with the regular
sine-wave mains power grid. However note that many have
been fried beyond repair when used with any kind of square-
wave source: inverter, UPS, etc. even "stepped sine" waveforms.

The problem appears to be the capacitive voltage divider used
to power the Kill-A-Watt electronics. The high frequency harmonics
deliver way too much power to the shunt regulator through the
capacitor and something fries.


Interesting, well mine is the 240V UK version which I got back before I
found them offered here but from looking at the buttons and display it's
obviously the same unit as the Kill A Watt. At any rate I've tested it and
it works well all the way down to 60VAC, and frequencies from 30 Hz all the
way up to nearly 400Hz where the readings start to get screwy. I've run it
off inverters, used an adapter to hook it up to my 240V central heat pump to
measure that, it's taken everything I've tossed at it and so far keeps
working.