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Old 06-10-2015, 09:05   #286
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Re: Why no Residential Fridges?

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Originally Posted by sailorchic34 View Post
Oddly Dimensionless, means it does not have length, but you can still count them, very much like electrons pass through a wire.

Even though a dimensionless quantity has no physical dimension associated with it, it can still have dimensionless units. To show the quantity being measured (for example mass fraction or mole fraction), it is sometimes helpful to use the same units in both the numerator and denominator (kg/kg or mol/mol).

The quantity may also be given as a ratio of two different units that have the same dimension (for instance, light years over meters). This may be the case when calculating slopes in graphs, or when making unit conversions. Such notation does not indicate the presence of physical dimensions, and is purely a notational convention. Other common dimensionless units are % (= 0.01), (= 0.001), ppm (= 10−6), ppb (= 10−9), ppt (= 10−12), angle units (degrees, radians, grad), dalton and mole. Units of number such as the dozen and the gross are also dimensionless."

So the number of electrons passing through a wire is dimensionless, but they are never the less actual units.
A ratio such as a you example of kg/kg is dimensionless because when you divide something by itself it always equals 1 thus the units cancel out. It's frequently useful to know the source units of the ratio but still it's dimensionless. The same can't be said of amp-hrs as amps times hours does not by definition equal 1 or any other pre-defined number.

Your "light-year" example is just an abreviation of the proper term. This often causes confusion among those who don't understand that it has no time factor even though it has "year" in the name. It is strictly a unit of length. It can take 1 year or a billion years to travel 1 light-year. (admittedly it does get confusing as you near the speed of light and relativity starts factoring in but I haven't come across a sailboat that does anything close to light speed, so we can stick to the simpler newtonian physics for this discussion).

Actually "dimension" isn't strictly limited to length. It can include time, mass electric charge, etc... Thus the number of electrons passing thru a wire has the dimension of electrons and therefore is not dimensionless. Same as if you have a bag of 50 oranges, oranges is the dimension.
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Old 06-10-2015, 10:20   #287
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Re: Why no Residential Fridges?

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The question was how many gph it can hold, not how fast you can fill it.

Sorry, I never flll jerry cans full as I can't lift a full jerry can.
As to 0 GPH, that would be when it's empty.
But GPH is a measure of how fast it fills up not how much it can hold.

How much does a GPH weigh?
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Old 06-10-2015, 10:22   #288
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Re: Why no Residential Fridges?

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I take you do not believe that displacement has anything to do with power produced by a combustion engine. I believe it is very likely that the HP figures you think are bogus can in fact be explained by displacement, compression ratio, rpm, admission pressure and # of strokes.

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Maybe I should rephrase it to continuous HP. Obviously there is relationship between engine output and engine variables. I just don't believe in there being a realistic comparison using bogus HP figures.
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Old 06-10-2015, 10:33   #289
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Re: Why no Residential Fridges?

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Maybe I should rephrase it to continuous HP. Obviously there is relationship between engine output and engine variables. I just don't believe in there being a realistic comparison using bogus HP figures.
Hence the reason they state horsepower at specified rpm. Car dealers state both HP and engine size consumers see a 3.5 Ltr engine that produces 165 HP at 5200 rpm and their mind says economical vehicle whereas 6.5 Ltr and 265 horse at 3500 rpm says pulling power ( numbers for illustration only not actual power or rpm numbers) and yes its called marketing.
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Old 06-10-2015, 10:42   #290
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Re: Why no Residential Fridges?

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Originally Posted by sailorchic34 View Post
The question was how many gph it can hold, not how fast you can fill it.

Sorry, I never flll jerry cans full as I can't lift a full jerry can.
As to 0 GPH, that would be when it's empty.
It can hold as many GPH as it can coulombs.
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Old 06-10-2015, 10:45   #291
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Re: Why no Residential Fridges?

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Hence the reason they state horsepower at specified rpm. Car dealers state both HP and engine size consumers see a 3.5 Ltr engine that produces 165 HP at 5200 rpm and their mind says economical vehicle whereas 6.5 Ltr and 265 horse at 3500 rpm says pulling power ( numbers for illustration only not actual power or rpm numbers) and yes its called marketing.
They list maximum HP. It's always been that way.

What freaks a lot of the old guys out is the old big blocks may have hit that peak HP at around 3500rpm and they redlined at 5000rpm. Some of these new engines may hit their peak at upwards of 5000-6000rpm and so they get nervous and don't take full advantage of the available HP. Then they complain that the new HP isn't the same.
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Old 06-10-2015, 10:47   #292
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Re: Why no Residential Fridges?

Some helluva thread drift. WTF does all this technical electro mumbo jumbo back n forth have to do with why there's no residential fridges in boats? :?:

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Old 06-10-2015, 10:59   #293
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Re: Why no Residential Fridges?

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Some helluva thread drift. WTF does all this technical electro mumbo jumbo back n forth have to do with why there's no residential fridges in boats? :?:

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Not a damn thing. I think it drifted starting with the relative power consumption?
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Old 06-10-2015, 11:07   #294
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Re: Why no Residential Fridges?

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Then they complain that the new HP isn't the same.

Just to ensure this wild thread drift, the "old" HP numbers and the "New" ones are not the same.
Old HP numbers were as installed, with stock exhaust and driving all the accessories, where new numbers are base engine, no accessories etc.
But there are many different "Horsepowers", take your pick

https://en.wikipedia.org/wiki/Horsepower
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Old 06-10-2015, 11:25   #295
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Re: Why no Residential Fridges?

OK here goes an attempt to tie it together somewhat my 12v DC fridge has an approx 1/2 HP electric motor turning at 2885 rpm cooling a 7 cf fridge and 2.5 cf freezer on about 60 watts power usage which figures out to about 4 amps draw for an acumulated 4 to 5 hours per day( 24 hour time frame) in the past week. So the power looks like this 4amp usage for 4 hours = 16 Ah to a high estimate of 4 amp usage for 5 hours =20 Ah that is with an average 70 deg average cabin temperature and a 60 deg average engine room temp ( where remote compressor unit is located )
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Old 06-10-2015, 11:27   #296
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Re: Why no Residential Fridges?

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Originally Posted by a64pilot View Post
Just to ensure this wild thread drift, the "old" HP numbers and the "New" ones are not the same.
Old HP numbers were as installed, with stock exhaust and driving all the accessories, where new numbers are base engine, no accessories etc.
But there are many different "Horsepowers", take your pick

https://en.wikipedia.org/wiki/Horsepower
Let's assume that we are talking bhp. Should unify the drift in that direction
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Old 06-10-2015, 11:40   #297
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Re: Why no Residential Fridges?

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Originally Posted by a64pilot View Post
Just to ensure this wild thread drift, the "old" HP numbers and the "New" ones are not the same.
Old HP numbers were as installed, with stock exhaust and driving all the accessories, where new numbers are base engine, no accessories etc.
But there are many different "Horsepowers", take your pick

https://en.wikipedia.org/wiki/Horsepower
actually the truth is hundred and eighty degrees opposite of what you just said
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Old 06-10-2015, 11:50   #298
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Re: Why no Residential Fridges?

Amp-hours are NOT a "true" measure of anything in particular except as it pertains to a particular battery (?) at a particular temperature (in degrees) at a particular SOC (in volts) at a particular discharge rate (amps) as measured by a particular resistance (in ohms) to a particular (arbitrary) SOC (in volts). Now someone of your dimensionless guys/gals please express this in a dimension.

The "true" capacity has to be something along the lines of capacity to do work. Amp-hours are a shortcut to that end but you. There is a defined standard that creates this shortcut dimension. It is meaningless without that standard. As is CCA or other battery measures. But it allows amateurs, i.e. non-pendantic buyers of batteries, to have some comparison figure to sort batteries and make "informed" choices. It has nothing in particular to do with anything else. Amp-hour "replenishment" or "usage" on a boat is a very complex problem to solve since it must involve temperature readings and discharge rates (never the same 20 ohm resistance in the "standard".

Not all batteries are equal when it comes to how long they can sustain a particular amp rate discharge, say at 100 amp rate vs. a 20 amp rate. You will get different numbers to get to the "standard" "fully dischared" voltage. A deep cycle battery will still have some capacity to do work, and it will recover quickly from a 100 amp rate for "x" to get to that artificial voltage, where it is arbitrarily declared discharged, so in fact it is very dependent on that measure.

Some of you belong on the forum for the "hopelessly correct about dimensions but impractical as to conveying usable information".
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Old 06-10-2015, 12:05   #299
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Re: Why no Residential Fridges?

Not approved for boat use, serious hazard potential.

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Old 06-10-2015, 12:09   #300
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Re: Why no Residential Fridges?

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Originally Posted by exMaggieDrum View Post
Amp-hours are NOT a "true" measure of anything in particular except as it pertains to a particular battery (?) at a particular temperature (in degrees) at a particular SOC (in volts) at a particular discharge rate (amps) as measured by a particular resistance (in ohms) to a particular (arbitrary) SOC (in volts). Now someone of your dimensionless guys/gals please express this in a dimension.

The "true" capacity has to be something along the lines of capacity to do work. Amp-hours are a shortcut to that end but you. There is a defined standard that creates this shortcut dimension. It is meaningless without that standard. As is CCA or other battery measures. But it allows amateurs, i.e. non-pendantic buyers of batteries, to have some comparison figure to sort batteries and make "informed" choices. It has nothing in particular to do with anything else. Amp-hour "replenishment" or "usage" on a boat is a very complex problem to solve since it must involve temperature readings and discharge rates (never the same 20 ohm resistance in the "standard".

Not all batteries are equal when it comes to how long they can sustain a particular amp rate discharge, say at 100 amp rate vs. a 20 amp rate. You will get different numbers to get to the "standard" "fully dischared" voltage. A deep cycle battery will still have some capacity to do work, and it will recover quickly from a 100 amp rate for "x" to get to that artificial voltage, where it is arbitrarily declared discharged, so in fact it is very dependent on that measure.

Some of you belong on the forum for the "hopelessly correct about dimensions but impractical as to conveying usable information".
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