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Old 04-10-2015, 04:59   #181
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Re: Why no Residential Fridges?

Quote:
Originally Posted by sailorchic34 View Post
………...

An ampere hour is simply the number of amperes (amps, A) used or stored in one hour. One could also use Ampere-day ( amp-day or amps per day) to define the number of ampere-hours used in one day. It's simple and quite clear.

But outside a university, amperes as a term is not used that much if at all. It's shortened to amp-hr, which is a contraction of the "proper" Ampere-hour term.

………..
SC, I dunno about the bit about universities, I reckon the term Amperes (or Amps) is pretty wide spread every place where electricity is discussed . However you are incorrect about it being shortened to amp-hr. Rather is has been bastardised and thus causes confusion.

EDIT: Perhaps I have mis-read your intention???? Maybe you are saying that the term Ampere is mainly used in universities while the rest of us use the term Amp????


And for the rest of us, the "proper" or standard unit of the quantity of electricity is not an "Ampere-hour", rather it is a Coulomb which equals one Ampere for one second or more conveniently 1 Ampere second.

Now most of us have by convention, used 1 hour as a more suitable time period rather than 1 second. We call this an Ampere hour and many shorten it to "amp-hour" (but not Ampere). But it is not the "standard", a Coulomb has that honour.

So if someone wants to use a day as the time period, they are free to do that and it should be easily understood by people of average intelligence. Thus that unit is an Ampere day (or amp-day). It is just as correct as using Ampere hour.

Any commonly used time period is valid as long as the units are stated. You might prefer Ampere week

For the mathematically challenged, here are some conversions.

1 Ampere week = 7 Ampere days = 168 Ampere hours = 604,800 Coulombs.
1 Ampere day = 24 Ampere hours = 86,400 Coulombs
1 Ampere hour = 3,600 Coulombs.

If you don't wish to use the standard unit of electrical quantity, feel free to use Ampere minute, or hour or day or whatever.

As a minor point of interest, the normally accepted unit in aviation when determining if there is sufficient battery capacity is an Ampere minute.
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Old 04-10-2015, 05:28   #182
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Re: Why no Residential Fridges?

Quote:
Originally Posted by sailorchic34 View Post
………..
An ampere hour is simply the number of amperes (amps, A) used or stored in one hour. One could also use Ampere-day ( amp-day or amps per day) to define the number of amperes-hours used in one day. It's simple and quite clear…….
There, I fixed it for you You can use Ampere days to define the number of Amperes used in a day but you can't use it to define the number of Ampere hours used in a day.

If you want to define the number of Ampere hours used in a day, you should use Coulombs per day but you can use Ampere hours per day .
Quote:
Originally Posted by StuM View Post
………..

If you have an average 2 Amp current flow for 30 minutes, you use 1 Amp hour of its 130 capacity . If you have the same 2 Amp current flow continuously for 24 hours, you use 48 Amp hours of that 130 capacity. [B]i.e 48 Amp hours per day.
…..
Or 2 Ampere days per day
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Old 04-10-2015, 08:25   #183
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Re: Why no Residential Fridges?

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Originally Posted by Wotname View Post
There, I fixed it for you You can use Ampere days to define the number of Amperes used in a day but you can't use it to define the number of Ampere hours used in a day.

If you want to define the number of Ampere hours used in a day, you should use Coulombs per day but you can use Ampere hours per day .

Or 2 Ampere days per day
Everything you said is quite correct with the exception of the part in red

There is no such thing as "the number of Amperes used in a day". You cannot "use" Amperes. An Ampere is a measure of the rate of current flow. It doesn't matter if it is flowing for a second or a day. It is still the same number of Amperes. Saying "Amperes used in a day" is equivalent to saying "number of gallons per minute moved in a day" by a pump. It is equally meaningless.
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Old 04-10-2015, 11:55   #184
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Re: Why no Residential Fridges?

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Originally Posted by StuM View Post
Everything you said is quite correct with the exception of the part in red

There is no such thing as "the number of Amperes used in a day". You cannot "use" Amperes. An Ampere is a measure of the rate of current flow. It doesn't matter if it is flowing for a second or a day. It is still the same number of Amperes. Saying "Amperes used in a day" is equivalent to saying "number of gallons per minute moved in a day" by a pump. It is equally meaningless.
Oh dear, There are Gallons per minute (GPM), gallons per hour (GPH) and gallons per day (GPD) All quite common units. Believe it or not, I have actually multiplied GPM by 60*24 to get gallons per day, in that engineering thingy that I do (calculating diesel fuel required in a 2 MW standby prime mover in a generator, actually seven of them in a row, all for one building). So it's not really meaningless at all. Quite handy sometimes....

For Ampere's as Watname so very clearly said, you can have Amperes per day (Ampere-day). Its just as valid as ampere hour or ampere minute. It's a measure of amperes per unit of time.
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Old 04-10-2015, 11:58   #185
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Re: Why no Residential Fridges?

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Originally Posted by Wotname View Post
However you are incorrect about it being shortened to amp-hr. Rather is has been bastardised and thus causes confusion.

And for the rest of us, the "proper" or standard unit of the quantity of electricity is not an "Ampere-hour", rather it is a Coulomb which equals one Ampere for one second or more conveniently 1 Ampere second.
Thank you sir for that lovely clarification on Ampere's and Coulombs. It broght a tear to my eye...
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Old 04-10-2015, 12:21   #186
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Re: Why no Residential Fridges?

Quote:
Originally Posted by Wotname View Post
SC, I dunno about the bit about universities, I reckon the term Amperes (or Amps) is pretty wide spread every place where electricity is discussed . However you are incorrect about it being shortened to amp-hr. Rather is has been bastardised and thus causes confusion.

EDIT: Perhaps I have mis-read your intention???? Maybe you are saying that the term Ampere is mainly used in universities while the rest of us use the term Amp????


And for the rest of us, the "proper" or standard unit of the quantity of electricity is not an "Ampere-hour", rather it is a Coulomb which equals one Ampere for one second or more conveniently 1 Ampere second.

Now most of us have by convention, used 1 hour as a more suitable time period rather than 1 second. We call this an Ampere hour and many shorten it to "amp-hour" (but not Ampere). But it is not the "standard", a Coulomb has that honour.

So if someone wants to use a day as the time period, they are free to do that and it should be easily understood by people of average intelligence. Thus that unit is an Ampere day (or amp-day). It is just as correct as using Ampere hour.

Any commonly used time period is valid as long as the units are stated. You might prefer Ampere week

For the mathematically challenged, here are some conversions.

1 Ampere week = 7 Ampere days = 168 Ampere hours = 604,800 Coulombs.
1 Ampere day = 24 Ampere hours = 86,400 Coulombs
1 Ampere hour = 3,600 Coulombs.

If you don't wish to use the standard unit of electrical quantity, feel free to use Ampere minute, or hour or day or whatever.

As a minor point of interest, the normally accepted unit in aviation when determining if there is sufficient battery capacity is an Ampere minute.
Thanks for also supporting a time period is a time period. If someone chooses Amp (ampere) day there isn't a thing wrong with it
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Old 04-10-2015, 15:05   #187
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Re: Why no Residential Fridges?

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Originally Posted by Cadence View Post
Thanks for also supporting a time period is a time period. If someone chooses Amp (ampere) day there isn't a thing wrong with it
Quite. An Ampere Day is a valid unit to measure the quantity of power used. But Amperes PER day(as SC keeps trying to use) is NOT - that it is not a measure of quantity but a measure of acceleration.

In another attempt to clarify:

Amperes, gallons per minute and feet per second are all one type of unit. They are a measure of "speed" in various forms.

The corresponding unit of "usage" or "consumption" at these speeds are
Amp hours, gallons and feet. You get the consumption or usage by multiplying the speed by the time.

Trying to use Amperes per hour or Amp/Hr is the equivalent of saying "gallons per minute per hour" or "feet per minute per minute". In effect you are trying to divide speed by time instead of multiplying speed by time.

As Jim Cate pointed out, some people need a lesson in dimensional analysis.
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Old 04-10-2015, 15:19   #188
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Re: Why no Residential Fridges?

Quote:
Originally Posted by StuM View Post
Quite. An Ampere Day is a valid unit to measure the quantity of power used. But Amperes PER day(as SC keeps trying to use) is NOT - that it is not a measure of quantity but a measure of acceleration.

In another attempt to clarify:

Amperes, gallons per minute and feet per second are all one type of unit. They are a measure of "speed" in various forms.

The corresponding unit of "usage" or "consumption" at these speeds are
Amp hours, gallons and feet. You get the consumption or usage by multiplying the speed by the time.

Trying to use Amperes per hour or Amp/Hr is the equivalent of saying "gallons per minute per hour" or "feet per minute per minute". In effect you are trying to divide speed by time instead of multiplying speed by time.

As Jim Cate pointed out, some people need a lesson in dimensional analysis.
I understood what she said and you should be able to decipher it as well all in all the technical of this argueing has nothing to do with using residential fridges on boats.
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Old 04-10-2015, 15:23   #189
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Re: Why no Residential Fridges?

Now I have a question for you stu will a G1 CME with a c3 pulse have any affect on my pwm solar controller
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Old 04-10-2015, 17:00   #190
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Re: Why no Residential Fridges?

Quote:
Originally Posted by StuM View Post
Quite. An Ampere Day is a valid unit to measure the quantity of power used. But Amperes PER day(as SC keeps trying to use) is NOT - that it is not a measure of quantity but a measure of acceleration.

In another attempt to clarify:

Amperes, gallons per minute and feet per second are all one type of unit. They are a measure of "speed" in various forms.

The corresponding unit of "usage" or "consumption" at these speeds are
Amp hours, gallons and feet. You get the consumption or usage by multiplying the speed by the time.

Trying to use Amperes per hour or Amp/Hr is the equivalent of saying "gallons per minute per hour" or "feet per minute per minute". In effect you are trying to divide speed by time instead of multiplying speed by time.

As Jim Cate pointed out, some people need a lesson in dimensional analysis.
I think anyone following understands the simple analogy or ampere being the amount of water coming through a hose at a given head of pressure, lets call that 12 volts. Now you can have a 48 gal drum (for simplicity) fill up in a day or have 48/24 and measure the amount in an hr.. Or 48gal/day or 2gal/hr.. Now if you have a pin hole in the bottom of the drum, or bucket, you might want to subtract that amount from the supplied amount for the same duration if you want to know what is in your drum or 2gal. bucket I haven't got the slightest idea what this has to do with the original post?
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Old 04-10-2015, 17:18   #191
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Re: Why no Residential Fridges?

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Amperes, gallons per minute and feet per second are all one type of unit. They are a measure of "speed" in various forms.
I'm so sorry, that is incorrect. Amperes and gallons are more closely related to volume and not speed at all. Gallons per minute have zero to do with speed. Speed would be a function of the velocity of the water or current density, rather then current. That would be related to pipe size with water or conductor size with current.
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Old 04-10-2015, 17:33   #192
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Re: Why no Residential Fridges?

One safety concern that hasn't been talked about is how home appliances are usually wired in a way that is considered dangerous for boats. As I understand it, the negative and green ground wires are usually connected in home appliances. On boats, they are supposed to be kept separate. Numerous wiring manuals I've read say that combining them presents a shock hazard to people on board. I won't try for an explanation why because I would probably mangle it. Maybe there is someone on the list who is better schooled in the reasoning behind this
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Old 04-10-2015, 17:40   #193
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Re: Why no Residential Fridges?

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One safety concern that hasn't been talked about is how home appliances are usually wired in a way that is considered dangerous for boats. As I understand it, the negative and green ground wires are usually connected in home appliances. On boats, they are supposed to be kept separate. Numerous wiring manuals I've read say that combining them presents a shock hazard to people on board. I won't try for an explanation why because I would probably mangle it. Maybe there is someone on the list who is better schooled in the reasoning behind this
On my fridge the ground is connected to the steel frame of the fridge. When at anchor my little inverter actually works as an isolated power supply as there isn't a ground reference. At the dock it would depend on how the boat was wired and how the dock boxes are wired. Always iffy.
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Old 04-10-2015, 18:23   #194
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Re: Why no Residential Fridges?

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I'm so sorry, that is incorrect. Amperes and gallons are more closely related to volume and not speed at all. Gallons per minute have zero to do with speed. Speed would be a function of the velocity of the water or current density, rather then current. That would be related to pipe size with water or conductor size with current.
That is the fundamental mistake you keep making and is the cause of all of this discussion. While gallon is closely related to volume. Ampere is NOT. It is closely related to Gallons per minute - it is the equivalent to Coulombs per second where the Coulomb is the equivalent of a Gallon (As clearly pointed out above, Coulombs can be directly converted to Amp Hours - not to Amps).

Gallons per minute has everything to do with speed. For a given pipe, the more gallons per minute you put through, the faster the water flows.
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Old 04-10-2015, 18:39   #195
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Re: Why no Residential Fridges?

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Originally Posted by StuM View Post
Quite. An Ampere Day is a valid unit to measure the quantity of power used. But Amperes PER day(as SC keeps trying to use) is NOT - that it is not a measure of quantity but a measure of acceleration.

In another attempt to clarify:

Amperes, gallons per minute and feet per second are all one type of unit. They are a measure of "speed" in various forms.

The corresponding unit of "usage" or "consumption" at these speeds are
Amp hours, gallons and feet. You get the consumption or usage by multiplying the speed by the time.

Trying to use Amperes per hour or Amp/Hr is the equivalent of saying "gallons per minute per hour" or "feet per minute per minute". In effect you are trying to divide speed by time instead of multiplying speed by time.

As Jim Cate pointed out, some people need a lesson in dimensional analysis.

Completely wrong. The only difference between "amp/hour" and "amp/day" is time. There is no other explanation.

I prefer, as do many others, to measure battery ins and outs in daily chunks. Makes much more sense because they can vary significantly during different times of the day. For instance, solar panels only charging during the daylight portion of the day.

The water analogy is helpful to people who don't or won't understand the practical application of this.
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