Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 15-08-2016, 09:47   #31
Registered User

Join Date: Nov 2013
Posts: 15
Re: House hold refrigerator off inverter

Make sure the home style appliances will accept the sin wave .
Some electronics will not work or burn up if the sin wave is not true also any voltage drops or overages will burn out the control boards.
Best to buy the least fancy of any appliances which are more reasonable in price anyways.
__________________

__________________
Sea Q is offline   Reply With Quote
Old 15-08-2016, 10:05   #32
Registered User
 
TeddyDiver's Avatar

Join Date: Aug 2010
Location: Arctic Ocean
Boat: Under construction 35' ketch
Posts: 1,647
Images: 2
Re: House hold refrigerator off inverter

Quote:
Originally Posted by Sea Q View Post
Make sure the home style appliances will accept the sin wave .
Some electronics will not work or burn up if the sin wave is not true also any voltage drops or overages will burn out the control boards.
Best to buy the least fancy of any appliances which are more reasonable in price anyways.
Not just that, with pure sin wave they are most efficient. Square or modified wave "corners" are wasted to heat the coils and that's wasted energy and may burn also the motor..
__________________

__________________
TeddyDiver is offline   Reply With Quote
Old 15-08-2016, 10:18   #33
Registered User

Join Date: Mar 2014
Location: Qatar
Posts: 91
Re: House hold refrigerator off inverter

Quote:
Originally Posted by Rorzech View Post
If you have a lid instead of a door then your cold air will stay inside instead of falling out on to the floor.
Sure, that's what everyone has been saying for the last 50 years. But exactly how much energy does air store compared to food, liquids, the structure of the fridge? We learned that stuff back in chemistry class decades ago and I don't recall the numbers, but it's obviously a very small fraction.

Perhaps it's time to debunk the myth, or at least look at things from a practical point of view. Assuming my previous numbers were correct, then moseriw's top loader with a 12v Danfoss consumes three times more energy than a store bought (super efficient) unit.

So even if my/your/their kids open and slam the fridge door shut all day long, then I doubt that energy consumption would go up by triple. If it is double then you're still ahead of the game.

To be devil's advocate, there are probably many on this thread who have built their own heavily insulated top loaders with super efficient Danfoss (or other units). So even if the energy consumption is the same, was it worth the man-hours and super high cost to build it? Plus household units operate at near-100% reliability. How many "marine" compressors can say the same thing?
__________________
makobuilders is offline   Reply With Quote
Old 15-08-2016, 10:30   #34
Registered User
 
Terra Nova's Avatar

Join Date: Apr 2007
Location: Marina del Rey, California
Boat: Freya 39 cutter- Terra Nova
Posts: 3,310
Re: House hold refrigerator off inverter

Quote:
Originally Posted by makobuilders View Post
...household units operate at near-100% reliability. How many "marine" compressors can say the same thing?
Absurd. Household units don't operate in a marine environment, never get tossed from side to side, with their contents crashing around inside, never have to beat to weather or take a pounding.
__________________
1st rule of yachting: When a collision is unavoidable, aim for something cheap.
"whatever spare parts you bring, you'll never need"--goboatingnow
"Id rather drown than have computers take over my life."--d design
Terra Nova is online now   Reply With Quote
Old 15-08-2016, 23:41   #35
Registered User

Join Date: Mar 2014
Location: Qatar
Posts: 91
Re: House hold refrigerator off inverter

Sure they do. A large percentage of trawlers over 40' are equipped with household refrigs, and almost all over 50' as well. Granted these are generally heavy powerboats versus sailboats, but they still get tossed around. And in cases where the powerboats are not stabilized (unfortunately my case as well) then the motion on the powerboat is much more uncomfortable than on a sailboat.

That being said, a cooling unit that is designed for the marine environment and is water cooled could be a wonderful, reliable unit, but there is nothing wrong with household units, and depending on the application and even budget, they offer advantages as well.
__________________
makobuilders is offline   Reply With Quote
Old 22-08-2016, 18:38   #36
Registered User

Join Date: Nov 2014
Location: PSL Florida
Boat: Cape Dory 25
Posts: 101
Re: House hold refrigerator off inverter

I appreciate everyone's input, I found a top loading freezer that draws only .45 amp after it chilled to temp, that seems very low? less than a half amp? as I recall you multiply amps by volts to get required wattage? is that correct? so .45 x 115v = 51.75 watts, so a 100watt inverter can run this ? doesn't feel right.
__________________
fishsail is offline   Reply With Quote
Old 22-08-2016, 18:57   #37
Marine Service Provider
 
newhaul's Avatar

Join Date: Sep 2014
Location: puget sound washington
Boat: 1968 Islander bahama 24 hull 182
Posts: 2,533
Re: House hold refrigerator off inverter

Quote:
Originally Posted by fishsail View Post
I appreciate everyone's input, I found a top loading freezer that draws only .45 amp after it chilled to temp, that seems very low? less than a half amp? as I recall you multiply amps by volts to get required wattage? is that correct? so .45 x 115v = 51.75 watts, so a 100watt inverter can run this ? doesn't feel right.
No a 100 watt I inverter won't do the job that is just the running amperage think 4x that as minimum start draw. ( error on the safe side)
__________________
newhaul is offline   Reply With Quote
Old 22-08-2016, 18:59   #38
Marine Service Provider
 
newhaul's Avatar

Join Date: Sep 2014
Location: puget sound washington
Boat: 1968 Islander bahama 24 hull 182
Posts: 2,533
Re: House hold refrigerator off inverter

Quote:
Originally Posted by Terra Nova View Post
Absurd. Household units don't operate in a marine environment, never get tossed from side to side, with their contents crashing around inside, never have to beat to weather or take a pounding.
There are many on here that would beg to differ with your assessment of domestic refrigeration.
__________________
newhaul is offline   Reply With Quote
Old 22-08-2016, 19:05   #39
Moderator
 
sailorchic34's Avatar

Cruisers Forum Supporter

Join Date: Feb 2011
Location: SF Bay Area
Boat: Islander 34
Posts: 4,394
Re: House hold refrigerator off inverter

Quote:
Originally Posted by Terra Nova View Post
Absurd. Household units don't operate in a marine environment, never get tossed from side to side, with their contents crashing around inside, never have to beat to weather or take a pounding.
LOL, Gee here I've used one continuously for 9 years now with a cheap MSW inverter (which runs the compressor fine BTW). Total cost ( fridge and inverter) about $200. I'm a cheap sailor.

It's bolted in and a clasp on the door to keep it closed when healed to port. It sometimes requires fast timing to open the door and grab something before things go flying. Has only happened once in 9 years... er maybe twice.
__________________
sailorchic34 is offline   Reply With Quote
Old 22-08-2016, 21:22   #40
Registered User
 
Terra Nova's Avatar

Join Date: Apr 2007
Location: Marina del Rey, California
Boat: Freya 39 cutter- Terra Nova
Posts: 3,310
Re: House hold refrigerator off inverter

Quote:
Originally Posted by Terra Nova View Post
Absurd. Household units don't operate in a marine environment, never get tossed from side to side, with their contents crashing around inside, never have to beat to weather or take a pounding.
Quote:
Originally Posted by sailorchic34 View Post
LOL, Gee here I've used one continuously for 9 years now with a cheap MSW inverter (which runs the compressor fine BTW). Total cost ( fridge and inverter) about $200. I'm a cheap sailor.

It's bolted in and a clasp on the door to keep it closed when healed to port. It sometimes requires fast timing to open the door and grab something before things go flying. Has only happened once in 9 years... er maybe twice.
Quote:
Originally Posted by newhaul View Post
There are many on here that would beg to differ with your assessment of domestic refrigeration.
You have both quoted me out of context. My reply, which you've quoted, was in response to this statement regarding "household refrigerators in houses". Not in marine service.

"Quote:
Originally Posted by makobuilders View Post
...household units operate at near-100% reliability. How many "marine" compressors can say the same thing?"
__________________
1st rule of yachting: When a collision is unavoidable, aim for something cheap.
"whatever spare parts you bring, you'll never need"--goboatingnow
"Id rather drown than have computers take over my life."--d design
Terra Nova is online now   Reply With Quote
Old 22-08-2016, 23:58   #41
Moderator
 
sailorchic34's Avatar

Cruisers Forum Supporter

Join Date: Feb 2011
Location: SF Bay Area
Boat: Islander 34
Posts: 4,394
Re: House hold refrigerator off inverter

Quote:
Originally Posted by Terra Nova View Post
You have both quoted me out of context. My reply, which you've quoted, was in response to this statement regarding "household refrigerators in houses". Not in marine service.

"Quote:
Originally Posted by makobuilders View Post
...household units operate at near-100% reliability. How many "marine" compressors can say the same thing?"
I had to go back and read the thread again, just to be sure. Makobuilders did not say household units in houses. That we are discussing household units in boats and the thread is about household fridge on a boat, sort of implies its about them in boats. Though I will give it to you that a household unit in a house does not experience very much rocking motion.

Myself, Back 9 years ago when I purchased the Rose, I actually had the cash to buy and install a marine compressor unit. But I felt that the overall compressor efficiency did not justify the absurd cost of a marine refrigeration system. Oh sure, Lot's of folks said that a home fridge would not work on a boat. It drew too much power and the compressor would fail from heeling.

Well it does draw a lot of power when it runs, but is has a rather short duty cycle, which makes it just about 2.5ah per hour, which ain't bad at all for a cheap dorm fridge..

Being an engineer I looked at the compressor design and the basic design of the 12V and 120V units is the same. The 12V unit has a smaller displacement and a dc to ac inverter. Both are oil bath recipicating. There is nothing in the "Marine" compressor that makes it withstand marine use.

Knowing that the amount of heat rejection required is the same no matter what the voltage is, I decided to experiment with a $120 fridge and a $45 cheap inverter. I figured worst case I'd toss it an get the $$$ marine unit. It's still working.

It has been 100 percent reliable over 9 years of constant liveaboard use, about 50 percent of that time at anchor and sailing and motoring. I have been at anchor now for 4 months since May 1st, moving about and there is no real down side. It just keeps on working. OK I did have the change out the cooling fan in the inverter a year or two ago, But that was $10 and 20 minutes.

When the fridge does fail, I'll toss it in the dump and get another one for $130 ish. I'm way ahead and saved a boat buck. Score.

The only real down side, is it works harder when cabin temperatures are 95F and above.
__________________
sailorchic34 is offline   Reply With Quote
Old 23-08-2016, 07:24   #42
Registered User

Join Date: Dec 2015
Posts: 123
Re: House hold refrigerator off inverter

I like how people think that air is "nothing" , but air is more dense than people realize . It can hold up 200 ton airplanes way up high where the air is very thin. Air down here where it is 14 PSIG can hold a large quantity of heat and moisture and both of those things rob your front loader fridge of an enormous amount of energy. Just because you can't see "air" it doesn't mean it isn't there and it won't magically stay out of the energy equation. If you have plenty of power, by all means abuse it however you please. I do. But if you're just getting by with barely enough power then going for every bit of efficiency you can get is the way to go.
That guy who said his top load freezer that only ate 50 watts of power could reduce his consumption buy half by relocating his compressor and condenser to a remote location just a few feet away from that freezer.
__________________
Rorzech is offline   Reply With Quote
Old 23-08-2016, 07:41   #43
Marine Service Provider
 
newhaul's Avatar

Join Date: Sep 2014
Location: puget sound washington
Boat: 1968 Islander bahama 24 hull 182
Posts: 2,533
Re: House hold refrigerator off inverter

Quote:
Originally Posted by Rorzech View Post
I like how people think that air is "nothing" , but air is more dense than people realize . It can hold up 200 ton airplanes way up high where the air is very thin. Air down here where it is 14 PSIG can hold a large quantity of heat and moisture and both of those things rob your front loader fridge of an enormous amount of energy. Just because you can't see "air" it doesn't mean it isn't there and it won't magically stay out of the energy equation. If you have plenty of power, by all means abuse it however you please. I do. But if you're just getting by with barely enough power then going for every bit of efficiency you can get is the way to go.
That guy who said his top load freezer that only ate 50 watts of power could reduce his consumption buy half by relocating his compressor and condenser to a remote location just a few feet away from that freezer.
50 watts is not a small amount of power and assuming a 50% duty cycle that equals just a bit over 40ah per day. And that's not a small amount to me I only generate about 50 ah off my solar . However I don't see how relocation of his compressor will change those numbers.
__________________
Non illigitamus carborundum
newhaul is offline   Reply With Quote
Old 23-08-2016, 08:00   #44
Registered User

Join Date: Mar 2014
Location: Qatar
Posts: 91
Re: House hold refrigerator off inverter

Quote:
Originally Posted by Rorzech View Post
I like how people think that air is "nothing" , but air is more dense than people realize... Air down here where it is 14 PSIG can hold a large quantity of heat and moisture and both of those things rob your front loader fridge of an enormous amount of energy.
Rorzech you make a good point and certainly a top loading fridge/freezer/icebox is better than front loader. However, the calculcations show that a modern, marine danfoss, top loader, custom made ice box burns about 44 watts per cf per day. Costs about $2500.

Meanwhile, a Carrefour-bought A+++ fridge, front loader, burns about 33 watts per net cf per day. Costs about $500. However, I admit that European appliances are more efficient than American units.

The point of this thread (I think) is that high efficiency household units are definitely practical to use on boats.
__________________
makobuilders is offline   Reply With Quote
Old 23-08-2016, 09:26   #45
Moderator
 
sailorchic34's Avatar

Cruisers Forum Supporter

Join Date: Feb 2011
Location: SF Bay Area
Boat: Islander 34
Posts: 4,394
Re: House hold refrigerator off inverter

Quote:
Originally Posted by Rorzech View Post
Just because you can't see "air" it doesn't mean it isn't there and it won't magically stay out of the energy equation. If you have plenty of power, by all means abuse it however you please. I do. But if you're just getting by with barely enough power then going for every bit of efficiency you can get is the way to go.
I actually did a quick calc of the power usage to exchange 2CF of air in my 3.5 cf fridge when the door opened s yrsr or do sgo. Air has mass, but it's not alot of mass at sealevel.

Air weights about 0.085 pounds per CF. Assuming 2 CF loss and 10 openings a day (which is lots), I would loose 1.7 pounds of air. That 1.7 pounds would require roughly 81 btu's to cool. There's moisture in it too, but close enough. So 81 BTU's equals ~25 watts. Add in motor efficiency losses and that rises to 40 watts or an additional 3.2ah per 24 hours.

So worst case there is an added 3.2 ah used per day. Really does not break the bank. That assumes that all the air has time to fall out of the fridge. While cold air is slightly heavier then warm air, It has a fairly slow rate of fall.

So not a biggy.

200 watts of solar panel was enough to run the fridge, lights and a small netbook. When I added colossus, my cad laptop, I had to add a third panel as it pulls as much as the Fridge, but does not have a duty cycle.
__________________

__________________
sailorchic34 is offline   Reply With Quote
Reply

Tags
inverter, refrigerator

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
Will refrigerator run on inverter ? Carver Heaven Electrical: Batteries, Generators & Solar 20 15-02-2015 16:15
Powering Full-Size 21 cu ft Refrigerator by Inverter simpleiron Electrical: Batteries, Generators & Solar 8 16-10-2010 14:05
Go Now or Forever Hold Your Peace Stillraining General Sailing Forum 19 23-03-2010 12:33
Beneteau Battery Hold Downs bene505 Construction, Maintenance & Refit 12 15-02-2009 09:12
Hold tank gravity empty question nautical62 Plumbing Systems and Fixtures 7 31-01-2009 09:15


Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 13:55.


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.