My backup power solution -- critique wanted.

Page 3 of 4  
wrote:

Lying about me again Brock? I suppose that one way to smear an opponent is try to convince others that they are a troll.
erniegalts
"_Magna est veritas et praevalebit"_ (Truth is mighty and will prevail).
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Michael Baugh wrote:

Don't *ever* respond to Ernie. He's like one of those clingy fat girls that craves any sort of attention, including being beaten over the head.
The things we learn to late (sigh).
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On Mon, 18 Aug 2003 19:04:50 -0400, "Stormin Mormon"

One should note..that the charging requirements for larger batteries often exceed the ability of small UPSs. Big batteries often require many amps to recharge, and a small UPS will think its a dead short or work its little ass off, until it burns up.
Gunner
Have you noticed how these enviros have become alarmed by the proliferation of large carnivores in the boonies? I saw one remark to the effect that bears, for example, do not seem to know their place on the "food chain." Why should they? Only man comes up with ideas like a food chain, and with man the idea only makes sense because man is armed. Without his weapons, man is by no means at the top of any food chain. On the contrary, he is down in fourth or fifth spot, depending upon the environment in which he lives. Primitive man was under no illusions about this, nor are the backwoods folk in India today. To a tiger, man is a morsel, as these unarmed joggers seem to be to a cougar, upon occasion. Man is man because he is always armed. That is something they do not teach in kindergarten, nor for that matter in high school. A youth becomes a man when he is first presented with his own personal weapon. That is his right of passage, and those who do not understand that are questionable members of a free society.         - Jeff Cooper's Commentaries, Vol. 9, No. 7, July, 2001
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mormon, you are seriously confused about units of measurement.
i

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Very possible that I'm quite ignorant. Happens now and again.
How do you explain the VA and watts situation?
--

Christopher A. Young
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Ignoring for the moment some subtleties involving phases and power factors, the basics (for direct current) are:
Energy = power x time (force x distance)
Energy can be expressed in many units, including BTUs, calories, kilocalories, ergs, joules, foot-pounds, watt-hours, kilowatt-hours, etc. The exact conversion factors are easily located.
Power is a thus Energy divided by time, or a _rate_ of energy usage.
Power is expressed in various forms, including watts, ergs/second, BTU/hour, etc. Again, exact conversion factors are easily located.
Ohm's Law: Volts = Current x Resistance
E = I R
Power = I^2 x R
(power is "I-squared R")
Volts is volts, current is amperes, resistance is ohms.
By the way, these are really just basic _physics_ notions, such as power being the rate at which work is done. And Newton's famous equation, F = ma, is of course very central to these other equations.
All of these things can be combined in some pretty obvious ways.
Fiddling with these symbols shows that
Power = voltage x current
Power = V A
This is how people make simple computations of the power consumption for something drawing 1 Amp at 12 volts. (The subtle issues of a.c. power and subtle discrepancies between a simple V A calculation and measured wattage are not too important, especially not until the basics are understood intuitively.)
The usual way to understand all of this is in terms of water flow in a hose. The water pressure is the voltage. The resistance is the amount of constriction in the hose. The current is the rate of water flow. It's useful to think about work done (energy) in moving water to high locations, etc. Energy = power x time, as always.
A light bulb of 100 watts, which is power, dissipates a kilowatt-hour in 10 hours, or 2.4 kWH per day of continuous operation. Look on your electric bill to see how much your utility is charging you per kWH. (Probably around 10 or 15 cents, for a cost per day of about 24-36 cents to keep a 100-watt bulb burning.)
The important thing to note is that _rates_ of energy usage and total energy used are NOT the same thing, and the units should never be confused.
This is what a few people were commenting on. For anyone familiar with the units, referring to total energy usage in terms of _watts_ is just plain obviously wrong.
It would be like saying the distance from Buffalo to Albany is 76 miles per hour.
You can worry about the subtle differences between rate power and VA
--Tim May
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Dear Tim, I'm familiar with evrything you wrote. I'm still quite clueless why someone else jumped my case.
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Christopher A. Young
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On Thu, 21 Aug 2003 15:59:25 -0400, "Stormin Mormon"

The question to which you responded was, essentially, "What is the difference between volt-amps and watts?"
You said:

Watts per hour? Presumably you meant watt-hour. There's a big difference.
1,000 VA battery? Assuming you were referring to battery capacity, the correct unit of measure would be amp-hours. It was especially confusing that you used VA, as that was one of the units in question. Volt-amps is the unit of measure of apparent power. See Ian's (or my) previous post for info on volt-amps.
BTW, the number on a light bulb is 95 watts, no unit of time needed (or wanted). If you run the light for an hour, you've expended 95 watt-hours of energy. If you run it for 30 minutes, you've expended 47.5 watt-hours of energy.
R, Tom Q.
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Hmm. Using RU for Rate of usage, and AP for ammount of power, lets see if I'm doing any better.
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Christopher A. Young
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For starters, please change your posting software to something more standard. You have apparently placed your comments in the .sig section of the post, causing my very standard posting software (which handles 99.99% of all Usenet replies just fine) to not be able to quote your comments.
I noticed you repeated your "95 watts per hour" mistake. No, it is NOT 95 watts per hour. Watts is a measure of instantaneous power. I explained this is detail, you said somewhere that you understood this, but quite clearly you did not.
You need to brush up on basic physics. Learn the difference between energy and power, between work and rate of work being done.
And get some better posting software, somehting that quotes articles properly.
--Tim May
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I apologize in advance for the terrible formatting of this post. Given Christopher's top-posting and unmarked editing of my previous post, I have no idea how to straighten it out.
Feel free not to page through this mess (that's probably wise), but please note that what Christopher quoted me as saying in his post, I DID NOT SAY.
My remarks will follow this unedited copy of his post: __________________________________________________________
On Fri, 22 Aug 2003 10:53:22 -0400, "Stormin Mormon"

The question to which you responded was, essentially, "What is the difference between volt-amps and watts?"
You said:

Watts per hour? Presumably you meant watt-hour. There's a big difference.
1,000 VA battery? Assuming you were referring to battery capacity, the correct unit of measure would be amp-hours. It was especially confusing that you used VA, as that was one of the units in question. Volt-amps is the unit of measure of apparent power. See Ian's (or my) previous post for info on volt-amps.
BTW, the number on a light bulb is 95 watts, no unit of time needed (or wanted). If you run the light for an hour, you've expended 95 watt-hours of energy. If you run it for 30 minutes, you've expended 47.5 watt-hours of energy.
R, Tom Q.
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Yes, I have the same problem with his posts. He adds comments at the top, usually includes the entire text of articles he is replying to, but then sometimes adds "CY:..." extra comments in the included text.
There are three cardinal sins many posters to Usenet are making these days:
1. Top-posting and including the entire previous article.
2. Bottom-posting, with the same full article inclusion. (Especially bad are the "Me, too!" and "I agree!" bottom posts.)
3. Doing a line-by-line rebuttal of very long articles with lots of included text from multiple authors. Those who engage with "Erniegalts" often do this, as he routinely copies an entire article and then adds comments. Life is too short to spend time trying to figure out who's saying what in these "novels."
I learned when I started posting, back around 1988, to try to get to orginal comments on the FIRST screenful of text. That is, only quote enough of an article to establish context. This is not always possible, but it's a good goal.
--Tim May
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It's obvious that I don't "get it", so I'll quit while I'm behind. I apologize also if anyone thought you looked inaccurate -- that sure wasn't my intent.
--

Christopher A. Young
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On Wed, 20 Aug 2003 20:35:18 -0700, Tim May

You really think that most people on this group are able to handle AC theory on power factors?
Hell, Tim, most have enough trouble with Ohms law, discrimination between electrochemical cells and "batteries", output of different types, why the "watt hour" measurement has been quietly abandoned, and so on. :-)
However, since the military and ex-military types seem determined to drive me off this group, perhaps doesn't matter.
erniegalts

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I had a look through that webpage. Seems to say that the power consumption of a motor is larger than the power output of a motor. That's interesting.
It didn't say much about the difference between VA and watt - hours, or maybe I wasn't paying attention. I've done that!
--

Christopher A. Young
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stormin, consumption is watts consumed output is rated in horsepower, and sure there is loss, in friction , heat and conversion of that electricity to mechanical energy. Your converter doesnt convert 100%, maybe 90 to 96% the loss is in heat
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On Fri, 29 Aug 2003 23:05:57 -0400, "Stormin Mormon"

Of course it is. There is no such thing in motors as 100%+ efficency.
Gunner

"The people who believe that, as a result of industrial development, life is about to become a hell, or may be one already, are guilty, at least, of sloppy pronouncements. On page 8 of Earth in the Balance, Al Gore claims that his study of the arms race gave him "a deeper appreciation for the most horrifying fact in all our lives: civilization is now capable of destroying itself."
In the first place, the most horrifying fact in many of our lives is that our ex-spouse has gotten ahold of our ATM card. And civilization has always been able to destroy itself. The Greeks of ancient Athens, who had a civilization remarkable for lack of technological progress during its period of greatest knowledge and power, managed to destroy themselves just fine." -- P.J. O'Rourke, All the trouble in the world. The lighter side of famine, pestilence, destruction and death.
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of course power consumption of a motor is higher than it's output. by 10% or thereabouts.
--
Steve Spence
www.green-trust.org
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On Sat, 30 Aug 2003 08:28:03 -0400, "Steve Spence"

At the least, and usually more.
Gunner
"You cannot invade the mainland United States. There would be a rifle behind each blade of grass." --Japanese Admiral Isoroku Yamamoto
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It's not at all unusual to find motors with efficiencies over 90%. Compared to other machines (reciprocating engines, pumps, boilers), motors are pretty efficient.
E.g. sites http://www.all-star-usa.com/motorefficiency03.htm and http://www.bge.com/cmp/CDA/discussion/0,1666,571,00.html show efficiencies for different motors varying from 0.68 to 0.94.
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