Is this the holy grail of RV/van Air Conditioners? DC Airco

[tx2sturgis]

Survey SAYS!

Amp hour, amp-hour or Ah is correct.

This is basic electrical theory and taught EVERYWHERE. (Its even in the wiki paragraph on display above)

Saying "amps per hour" is not correct, it makes NO sense electrically. We dont divide amps per unit of time, we multiply them.

It does not matter if it sounds the same, or you think it is saying the same thing, it is not.

 

[IGBT]

Sorry, you're just wrong.

Amps measures electric current, the flow of electric charge. It is already a rate over time, specifically one coulomb per second. 

It makes no sense whatsoever to say "25 amps flowing in a microsecond"

For a capacitor you would normally say discharge, or 25 amps discharged in a microsecond.
This is just standard EE talk.   An amp is one coulomb per second.   A capacitor charged with 25 coulombs could provide 25 amps for one second.   A capacitor charged with 25 micro coulombs could provide 25 amps for one microsecond (assuming negligible internal resistance of the capacitor).
Thus you can totally say 25 amps flowing (discharging) in a microsecond.
I studied electrical engineering at Georgia Tech.  What is your background may I ask?

 

[tx2sturgis]

I studied electrical engineering at Georgia Tech.  What is your background may I ask?

We're all talking about the same thing, and saying the same thing, BUT.

It's the nomenclature that is causing the issue.

Its like arguing about the torque rating of a motor.

"Foot pounds" is how we SAY it, normally, but someone trained in mechanical physics will say "pounds-feet".

Its all the same for purposes in this forum.

 

[IGBT]

Survey SAYS!

Amp hour, amp-hour or Ah is correct.

This is basic electrical theory and taught EVERYWHERE. (Its even in the wiki paragraph on display above)

Saying "amps per hour" is not correct, it makes NO sense electrically. We dont divide amps per unit of time, we multiply them.

It does not matter if it sounds the same, or you think it is saying the same thing, it is not.

per
pər/
preposition
preposition: per

1. 1.
   for each (used with units to express a rate).
   "a gas station that charges $1.29 per gallon"
   
2. 2.
   archaic
   by means of.
   "send it per express"

Per means for.   25 amps FOR EACH hour.   Thus if you say 25 amps per hour you are saying 25 amps for each hour of use, or 600 amps constant current in a 24 hour period.   You can also just say 600AH or 25AH.

Damn, this is like arguing over how to pronounce pecan

This forum really gets ridiculous sometimes.

 

[tx2sturgis]

Per means for.   25 amps FOR EACH hour.  

{snip}

This forum really gets ridiculous sometimes.

Not in electrical theory. It should be stated as 25 amp-hours FOR an hour, or whatever. Amps that are flowing ALREADY have a time quantity of one second figured in. Thats how they are defined. There is NO such thing as an amp that is NOT flowing, like a gallon of gas or water that is sitting in a container.

And yeah, its minutia.

Sorta.

See my post number 52 above.

_________________________

Then lets have a beer and impress the women folk,

with brainy talk of amps and volts!

 

[IGBT]

Here is some lingo from around the web:

"Most batteries' A.H. capacity is stated for the 20-hour rate of discharge. This means that a battery has a 100 A.H. capacity if it is discharged over 20 hours, or at about 5 Amps-per-hour (100 A.H. / 20 hours = 5 Amps DC)."

https://www.batteryweb.com/pdf/inverter_battery_sizing_faq.pdf

" If our 80 amp hour battery is 100% dead (100% depth of discharge) we can assume that it will take the 85 watt solar module 16 hours of full sun to completely restore the depleted 80 amp hours (80 amp hours divided by 5 amps per hour). In reality because of battery inefficiency and other factors such as temperature and battery type it will take slightly longer."

http://www.sunelco.com/class_electricity.html


I can't believe I let you guys troll me like this...

 

[IGBT]

Not in electrical theory. It should be stated as 25 amp-hours FOR an hour, or whatever. Amps that are flowing ALREADY have a time quantity of one second figured in. Thats how they are defined. There is NO such thing as an amp that is NOT flowing, like a gallon of gas or water that is sitting in a container.

No, no no!   Amps are not charge.  Coulombs are charge.  The time quantity factored into amps is how much charge flows in one second.
If you want to relate it to gasoline you would say coulombs are sitting in a container (which actually is what they are doing inside a charged capacitor with unconnected leads).

It is very confusing to try to use amps and assume a built in time quantity, especially for a device like a refrigerator which has a variable draw depending on if the compressor is on.   

"The refrigerator draws 25 amps"

"The refrigerator uses 25 amps for each hour of operation"

Not really the same thing.   They might be the same thing but in the first sentence perhaps the refrigerator draws 25 amps at startup of the compressor and then 10 amps when it is running, or perhaps the refrigerator is set for a temperature in which case it only runs for 30 minutes each hour and thus draws an average of 12.5 amps for each hour of operation"

"The refrigerator consumes 25AH at 12V"

"The refrigerator uses 25 amps for each hour of operation at 12V"

"The refrigerator uses 300 watts for each hour of operation"

"The refrigerator consumes 300WH"

Much clearer.  All four statements should be interpreted the same by sane, non-CRV users in the world.

 

[tx2sturgis]

Here is some lingo from around the web:


I can't believe I let you guys troll me like this...

'Lingo'?

Oh well hell, if its 'lingo from around the web', pardon me, it MUST be correct.



IGBT, you sound just a tiny bit like the OP...no matter what is presented, you cant be bothered with facts.

I'm pretty sure you and I would have a blast sitting around a campfire figuring this stuff out...

 

[RVTravel]

Going out to buy more popcorn for this show.

 

[tx2sturgis]

No, no no!   Amps are not charge. 

{snip}

{1}"The refrigerator draws 25 amps"

{2}"The refrigerator uses 25 amps for each hour of operation"

Not really the same thing.  

I did not say amps were level of charge. They are not and I did not say they were. Please don't misquote me. I said they can NOT be a static quantity. (Coulombs CAN be a static quantity).

Correct. Sentence {1} is valid. Sentence {2} is NOT valid, in electrical theory.

It CAN consume 25 Ah (or amp-hours) in say, a 24 hour day, or whatever.
Meaning, it pulled 25 amps for an hour, then rested for 23 hours, or it pulled about 0.99 amps, more or less, for the 24 hours.

 

[IGBT]

Lingo just meaning that using the term per instead of "for each" has been accepted on the internet.

Maybe it is not strictly accepted in PHD documents.  I am not doing that much research to find out.


Ok, one last shot here.

I happen to have a laser that is rated at 20 kilowatt pulses.   Watt also includes time since it is volts times amps and amps includes time.

So what can I do with this laser?   The military uses a 20 kilowatt laser to shoot down missiles.

My 20 kilowatt laser can barely punch a hole in a razor blade.

So what are we missing here?   Why is my 20 kilowatt laser not the same as the military 20 kilowatt laser?

 

[tx2sturgis]

Going out to buy more popcorn for this show.

Buttered?

 

[tx2sturgis]

My 20 kilowatt laser can barely punch a hole in a razor blade.

So what are we missing here?   Why is my 20 kilowatt laser not the same as the military 20 kilowatt laser?

I suppose you are refering to the duty cycle, in other words, the TIME the laser is on vs the time the laser is off.

Dude, put that thing in a sturdy and well padded shipping carton, mail it to me, and I will spend the next 2 months 'testing' my theory!

I LOVE lasers!

Tell me more!

 

[Gideon33w]

This is mostly a colloquial wording issue. Not really relevant to explaining usage to 99.99% of people. I'd say that Tx2sturgis is the most right since he isn't running into the problem of goofy wording. IGBT is giving the most technical answers but still running into the technical vs colloquial issue at times.

Either way, we should be teaching new members (and old) to convert everything to WH for the sake of our sanity. This would also make explaining the sizing of a solar array far simpler.

Oh, and I was a Military Intel and Electronic Warfare Systems Maintainer/Integrator and my degree is in Electronic Technologies ... And I've been avoiding chiming in just to watch the show ...

 

[tx2sturgis]

And I've been avoiding chiming in just to watch the show ...

Chikin!

 

[Gideon33w]

Chikin!

An amp is a fixed amount of force. A coulomb is the net flow of 1 amp over 1 second. Or, you can look at it as 1 amp being 1 coulomb moving over a given point per second. Amps are for fixed (or average) force and coulombs are for that force over periods of time. Could you use amp hours in place of coulombs? Obviously, and that's what most of us do. 

Amps to Coulombs is like Watts to Joules. - If that is helpful for anyone.

Anyways ... Who cares? We are getting into details far beyond what is needed to explain the point. But, I guess that minutia is the foundation of all good internet arguments ... lol

 

[Gideon33w]

Boy ... You know, it has been so long I'm actually questioning my own wording choices there and I'm tempted to go grab one of my books and just quote it instead, lol. - But, I guess that helps prove how little this actually matters, hahahahaha --- And I taught this stuff ...

 

[tx2sturgis]

Either way, we should be teaching new members (and old) to convert everything to WH for the sake of our sanity. This would also make explaining the sizing of a solar array far simpler.

I agree, but batteries are not normally rated at watt-hours, and solar panels are only rated in watts or amps, (voltage of course also) so incoming folks get confused in a hurry doing the calculations if they have not had some background in this stuff.

So, WH is often the result we seek, usually, but we have to trip over amps and volts getting there.

BTW, my early years were spent in electronics, as if you could not tell.

Three years in high school vocational electronics, then one year in college level electronics, followed by four years on the job electronics repairs, component level, practical experience.

And 2 years in there working in electronics retail sales and marketing. And I painted houses part time for extra money too!

Plus 30 years working with electronics in the ham radio hobby, building and servicing repeaters, radios, power supplies, duplexers, antennas, mobile electronics, installing emergency comm centers, building computers, installing digital, voice, and internet communications systems, etc etc etc...

Its who I am...the truck driving thing was just to put beans on the table and a roof over my head.

Many years ago I discovered that for me, electronics was a really fun hobby, but made for a lousy career, in my part of the world anyway. I suppose if I had moved to silicon valley, and went to work for Apple or Motorola, we would be having a very different conversation.

Anyway, thanks for the vote of confidence!

 

[John61CT]

Here is some lingo from around the web

Yes these terms are very commonly misused, and that causes a lot of confusion.

I studied electrical engineering at Georgia Tech.

Obviously understanding basic concepts and terminology does not require lengthy education.

"The refrigerator uses 25 amps for each hour of operation"

Has no meaning. Perhaps 25 AH per hour is what is meant? but unclear. Same with

"30 minutes each hour and thus draws an average of 12.5 amps for each hour of operation"

"The refrigerator uses 300 watts for each hour of operation"

Running at (perhaps an average of) X watts **over** Y hours is, meaningful. Used up Z watt- hours during that time. . .

"The refrigerator consumes 25AH at 12V"

"The refrigerator consumes 300WH"

Also nonsensical, both missing how long it takes for it to consume that amount of power.

"The refrigerator draws 25 amps"

This is 100% clear, and the only example that is.

Perhaps better if clarified with "average when compressor running X% of the time", as opposed to "while the compressor is operating"

 

[Gideon33w]

That's why I said to CONVERT everything to WH, haha. I know it's a pain but so is explaining this all to most people.

I spent 5 years as a 33W (now 35T) in the Army with that fun MOS job description I wrote earlier. The next 5 years were spent working for the DoD as a civilian with similar fun titles like "Senior Computer Network Technologist II". First job after getting out was teaching soldiers how to do what I did and last DoD job was that last title which had nothing to do with the actual job of building video game based training tools for the Army. At the end of my active duty stint I worked the last Army electronics shop to do in-house component level maintenance. A pretty boring job but at that point I was so broken I couldn't do the fun things anymore and was now non-deployable.

It was fun times. I like problem solving.