Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 02-10-2015, 09:52   #121
Marine Service Provider
 
SV THIRD DAY's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: La Paz, Mexico
Boat: 1978 Hudson Force 50 Ketch
Posts: 3,653
Re: Why no Residential Fridges?

Quote:
Originally Posted by Poster View Post
As long as we're digressing into pedantry, there's another problem with Ah: it's only really useful if you live primarily or exclusively in a 12V world.

Not so, for me. Computing devices mostly use 5V. 12V bus on the RV. 24V bus on a big boat. 36V and 48V on my electric bike batteries. 60V on my solar strings. 120V from inverter and shore. (240V if we're traveling overseas in a cruiser!)

So Ah is pretty awkward, and I find it easier to think in Wh to be able to make comparisons and reason about energy usage.
Now we have just gone mad folks....

An Amp Hour into and out of your batter bank is an Amp Hour no matter no how you take it out or put it back into your battery bank!

I give up.....

But this should be a GREAT example of why you...ah...well....

Oh never mind, saying the obvious will get you labeled a hater, bully or know it all in a world that doesn't like a truth teller, so I will just shut up and get back to work.
__________________

__________________
Rich Boren Goodbye Morro Bay...Hello La Paz, Mexico and the owner of:
Cruise RO Water High Output Water
Technautic CoolBlue Refrigeration
SV THIRD DAY is offline   Reply With Quote
Old 02-10-2015, 09:56   #122
Registered User
 
redhead's Avatar

Join Date: Mar 2011
Location: PNW 48.59'45N 122.45'50W
Boat: Ian Ross design ketch 63'
Posts: 764
Images: 5
Re: Why no Residential Fridges?

And here's another side....

I am currently learning about the power draw of various things in my new/old boat. We are currently discussing what must be upgraded vs what should be upgraded vs what we can afford.

Pissing contest or not, I have learned more following this thread than in the last 15 months of reading all the books (including Calder I'm ashamed to admit).
Actually, your back and forth bashing and witty repartee's kept my interest up and my brain a chance to catch it's breath. I am now marginally smarter than I was before.

And for that, I thank you!
__________________

__________________
redhead is offline   Reply With Quote
Old 02-10-2015, 09:58   #123
Senior Cruiser
 
newhaul's Avatar

Cruisers Forum Supporter

Join Date: Sep 2014
Location: puget sound washington
Boat: 1968 Islander bahama 24 hull 182, 1963 columbia 29 defender. hull # 60
Posts: 3,992
Re: Why no Residential Fridges?

Quote:
Originally Posted by SV THIRD DAY View Post
Now we have just gone mad folks....

An Amp Hour into and out of your batter bank is an Amp Hour no matter no how you take it out or put it back into your battery bank!

I give up
Agreed.
Now get back to fix in your house. Mexico is calling.
__________________
newhaul is online now   Reply With Quote
Old 02-10-2015, 10:00   #124
Registered User
 
TeddyDiver's Avatar

Join Date: Aug 2010
Location: Arctic Ocean
Boat: Under construction 35' ketch
Posts: 1,828
Images: 2
Re: Why no Residential Fridges?

Quote:
Originally Posted by SV THIRD DAY View Post
Ahhhh....there are no more German made Danfoss compressors, hasn't been for years.
It was not me who brought up "German made Danfoss" compressors into this discussion. I just made a point that the actual compressors are the same whatever AC/DC 12/110/240V whatever...
BR Teddy
__________________
TeddyDiver is offline   Reply With Quote
Old 02-10-2015, 10:23   #125
Marine Service Provider
 
SV THIRD DAY's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: La Paz, Mexico
Boat: 1978 Hudson Force 50 Ketch
Posts: 3,653
Re: Why no Residential Fridges?

Quote:
Originally Posted by TeddyDiver View Post
It was not me who brought up "German made Danfoss" compressors into this discussion. I just made a point that the actual compressors are the same whatever AC/DC 12/110/240V whatever...
BR Teddy
This is where I should just shut up and let it go...but it's also where Cruise Rumors come from, so forgive me for jumping in and clarifying the above statement, I promise I'm not trying to be an ass (at least not today anyway).

It IS 100% correct that a 12v/110v/240v (Danfoss compressor for example) IS indeed the SAME exact compressor with just a different controller to accept the different voltages and current types.

But lets not give the totally wrong impression that a Danfoss compressor (again for example) is the same as brand X, Y, or Z in terms of power consumption (dare I say Amp*Hrs) per Btu cooling capacity. The compressor units I'm pulling out of these dorm type refrigerator and sending to the recycling center and replacing with ours are a JOKE in terms of energy efficiency. You can call them energy star or green all you want, but they suck. If they didn't hell I would just keep them in the unit and save all the expense of a new compressor, soldering, vacuuming down, recharging, bla bla bla and just swap out the 120v AC controller with a new 12v DC controller.

That's what some people are missing that don't have the benefit of the side by side testing data. There is a false assumption that the only issue on the table here is the 12v DC vs 120v AC power input. No, there is a difference in efficiency in the compressor itself regardless of the voltage. Trust me if all these marine refrigeration companies using the high priced Danfoss BD35/50 could switch to the no name made in China compressor and not get kicked in the teeth for energy usage they would.
__________________
Rich Boren Goodbye Morro Bay...Hello La Paz, Mexico and the owner of:
Cruise RO Water High Output Water
Technautic CoolBlue Refrigeration
SV THIRD DAY is offline   Reply With Quote
Old 02-10-2015, 10:44   #126
Registered User
 
Cadence's Avatar

Join Date: Dec 2008
Location: SC
Boat: None,build the one shown of glass, had many from 6' to 48'.
Posts: 6,062
Re: Why no Residential Fridges?

Quote:
Originally Posted by StuM View Post
I know I'm a pedantic old fart, but this misuse of units really grates with me.

It's not Amp/hr or Amp/day (the slash is a "divide" sign) . It's Amp Hours or Amp Hrs/Day. If you are pulling 4 Amps for 2 hours you use 4 x 2 = 8 Amp Hrs. Not 4/2 =2 Amp/hrs.

Edit: And you can't "store Amps" An Amp is the basic SI unit of current flow
Lighten up. Every body knew it was per not divided by.
__________________
Cadence is offline   Reply With Quote
Old 02-10-2015, 11:15   #127
Senior Cruiser
 
newhaul's Avatar

Cruisers Forum Supporter

Join Date: Sep 2014
Location: puget sound washington
Boat: 1968 Islander bahama 24 hull 182, 1963 columbia 29 defender. hull # 60
Posts: 3,992
Re: Why no Residential Fridges?

Quote:
Originally Posted by StuM View Post
I know I'm a pedantic old fart, but this misuse of units really grates with me.

It's not Amp/hr or Amp/day (the slash is a "divide" sign) . It's Amp Hours or Amp Hrs/Day. If you are pulling 4 Amps for 2 hours you use 4 x 2 = 8 Amp Hrs. Not 4/2 =2 Amp/hrs.

Edit: And you can't "store Amps" An Amp is the basic SI unit of current flow
If you read what all the battery manufacturers say on the top of a cars starting battery you can store amps in my old pickup I had two batteries that said 1200 CCA on the top which meant I had 1200 amps available in the battery at 32f or 0c
__________________
newhaul is online now   Reply With Quote
Old 02-10-2015, 11:26   #128
Senior Cruiser
 
Scot McPherson's Avatar

Cruisers Forum Supporter

Join Date: Apr 2010
Location: Shoreline, CT and Portmouth Harbor
Boat: Standfast 33, building a 65 ft Wooden Schooner
Posts: 631
Re: Why no Residential Fridges?

That's not stored amps, that's how much the battery can produce in a single shot. The total number is WAY higher than that


Sent from my iPhone using Tapatalk
__________________
Captain Scot, 100 Ton Master, w/Sailing and Towing
Daring Kids to be Exceptional
http://americanseafarers.us
Scot McPherson is offline   Reply With Quote
Old 02-10-2015, 11:30   #129
Senior Cruiser
 
newhaul's Avatar

Cruisers Forum Supporter

Join Date: Sep 2014
Location: puget sound washington
Boat: 1968 Islander bahama 24 hull 182, 1963 columbia 29 defender. hull # 60
Posts: 3,992
Re: Why no Residential Fridges?

Quote:
Originally Posted by Scot McPherson View Post
That's not stored amps, that's how much the battery can produce in a single shot. The total number is WAY higher than that


Sent from my iPhone using Tapatalk
As a mechanical engineer I do understand that however I was just giving an easily read example of storing amps
__________________
newhaul is online now   Reply With Quote
Old 02-10-2015, 11:35   #130
Marine Service Provider
 
SV THIRD DAY's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: La Paz, Mexico
Boat: 1978 Hudson Force 50 Ketch
Posts: 3,653
Re: Why no Residential Fridges?

Quote:
Originally Posted by Scot McPherson View Post
The total number is WAY higher than that
Yep...enough to turn a 9/16" wrench into a resister and melt.

Don't ask me how I know.....
__________________
Rich Boren Goodbye Morro Bay...Hello La Paz, Mexico and the owner of:
Cruise RO Water High Output Water
Technautic CoolBlue Refrigeration
SV THIRD DAY is offline   Reply With Quote
Old 02-10-2015, 11:54   #131
Registered User

Join Date: Apr 2013
Location: So Cal
Boat: Catalina 30
Posts: 943
Re: Why no Residential Fridges?

Quote:
Originally Posted by SV THIRD DAY View Post
Yep...enough to turn a 9/16" wrench into a resister and melt.

Don't ask me how I know.....
I think many of us have had that exact same experience.
__________________
jeepbluetj is offline   Reply With Quote
Old 02-10-2015, 12:04   #132
Senior Cruiser
 
Scot McPherson's Avatar

Cruisers Forum Supporter

Join Date: Apr 2010
Location: Shoreline, CT and Portmouth Harbor
Boat: Standfast 33, building a 65 ft Wooden Schooner
Posts: 631
Re: Why no Residential Fridges?

Quote:
Originally Posted by SV THIRD DAY View Post
Yep...enough to turn a 9/16" wrench into a resister and melt.

Don't ask me how I know.....

I know how you know. I blew a screw-driver in half once, and the slag burned my hand pretty good and black. I think about a dime size spot was 3rd degree burned instantly.


Sent from my iPhone using Tapatalk
__________________
Captain Scot, 100 Ton Master, w/Sailing and Towing
Daring Kids to be Exceptional
http://americanseafarers.us
Scot McPherson is offline   Reply With Quote
Old 02-10-2015, 12:04   #133
Registered User
 
TeddyDiver's Avatar

Join Date: Aug 2010
Location: Arctic Ocean
Boat: Under construction 35' ketch
Posts: 1,828
Images: 2
Re: Why no Residential Fridges?

Quote:
Originally Posted by SV THIRD DAY View Post
No, there is a difference in efficiency in the compressor itself regardless of the voltage. Trust me if all these marine refrigeration companies using the high priced Danfoss BD35/50 could switch to the no name made in China compressor and not get kicked in the teeth for energy usage they would.
Ok, but the difference is in the speed controller circuit IMHO, not in the compressor itself..
__________________
TeddyDiver is offline   Reply With Quote
Old 02-10-2015, 14:02   #134
Moderator
 
sailorchic34's Avatar

Cruisers Forum Supporter

Join Date: Feb 2011
Location: SF Bay Area
Boat: Islander 34
Posts: 4,815
Re: Why no Residential Fridges?

Quote:
Originally Posted by TeddyDiver View Post
Ok, but the difference is in the speed controller circuit IMHO, not in the compressor itself..
Ah, but part load performance, that is with the compressor ramped down a bit to say 70% rpm might very well increase the COP / efficiency. I, "cough", forgot about those new fancy variable speed 12v compressors. So Rich's fridges can be more efficient, under many conditions.

I agree that the basic compressor design, ie reciprocating piston compressor has a base efficiency. Part load performance though can provide increased COP and lower energy draw.

What would be really cool is to put a data logger on both the 12V and 120V fridges (with inverter), in a boat and log the cool down and day to day energy draw in 70, 80 and 90 degree temps for a week. Oh sure one could use a room with a heater too to simulate different cabin temperatures.

My though is that for a given box that the heat gain into the box will be the same at a given temperature, so that overall the same amount of work/ heat transfer has to happen. While the 12V VSD compressor can be more efficient, it also runs longer. where as the 120V compressor has only a few minute cycle time. So it can be less efficient, but if it only runs 1/3 the time of a 12V compressor, the overall loss to inefficiency is not so great.
__________________
sailorchic34 is offline   Reply With Quote
Old 02-10-2015, 14:20   #135
Senior Cruiser
 
colemj's Avatar

Cruisers Forum Supporter

Join Date: Oct 2005
Location: Presently on US East Coast
Boat: Manta 40 "Reach"
Posts: 10,049
Images: 12
Re: Why no Residential Fridges?

Quote:
Originally Posted by SV THIRD DAY View Post
Yep...enough to turn a 9/16" wrench into a resister and melt.
Isn't that called a "fuse" and not a "resistor"?

Mark
__________________

__________________
www.svreach.com

You do not need a parachute to skydive. You only need a parachute to skydive twice.
colemj is offline   Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Wanted: Residential Mooring (UK) Genzzry Liveaboard's Forum 12 06-10-2015 12:46
Longish residential sailing course wanted woodyapex General Sailing Forum 12 13-05-2015 23:06
Difference Between Residential and Marine AC Circuit Panels ? albergsailor Electrical: Batteries, Generators & Solar 8 21-09-2011 13:56
Residential Canals in South FL j0n Atlantic & the Caribbean 21 24-02-2011 06:31
Residential Stainless Steel Sinks? Extemporaneous Plumbing Systems and Fixtures 17 03-05-2009 16:15



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 13:36.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.