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Old 13-08-2016, 09:31   #16
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Re: House hold refrigerator off inverter

I contacted Samsun and LG both about their digital inverter fridges. However they both stated that the fridge requires a cooling space on the sides and top. I believe that the evap coils are probably located on the walls or back.
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Old 13-08-2016, 09:53   #17
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Re: House hold refrigerator off inverter

The evaporators are wrapped next to the box and insulation is molded around them. then they wrap with reflective tape and install the condenser unit around it before putting on the tin. This is why the sides and top of a household fridge are hot and why they run so much. It's also what got me thinking of isolating the condenser and compressor from the fridge to get it to run less..
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Old 13-08-2016, 12:33   #18
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Re: House hold refrigerator off inverter

I run a small domestic fridge 650 w 220v on an inverter .over a 7 hour period it used 2kw of power to run in 20 degree climate .6 or 7 kw per day , taking in to account an inverter loss of 15 percent for a cheap inverter and then subtracting from this loss that an inverter on standby is only on when the fridge motor is on, the loss is very small ,I need to produce more than say 7 kw to not kill the batterys .I have no idea what a dc fridge uses all i can say is that the inverter loss is not big on a cheap pure sine wave inverter .The fridge cost 100 euro the inverter 220 euro . hope this helps
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Old 13-08-2016, 12:53   #19
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Re: House hold refrigerator off inverter

Since everyone has different size reefers I think we should start looking at amps per cubic foot to get a better understanding of efficiency.


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Old 13-08-2016, 13:19   #20
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Re: House hold refrigerator off inverter

Quote:
Originally Posted by moseriw View Post
Yes I know sailorchic prefers the cheap fridges.

Houshold fridges are front loaders.
On board you should have a top loader to prevent the cold air falling out!
You have a wind generator and solar.

I built my own top loader fridge with 140 liters and
a WAECO cooling machine for around 600 Euros.

Result:
that thing consumes with 50% Fridge and 50% freezer about 1,6 Ah when it is cooled down.

Sailorchic is a marvelous technician so she certainly will post her consumtions.
We have gone pretty much 12V and gas for our needs in Med.
Have installed 12V sockets in convenient areas and charge phones etc with these using USB. DELL laptops have 12V socket chargers.
Have two 12V "Eskys" when we are only two on board we use the $80 Walmart fridge. With visitors we add the 12V 60 Lidle fridge as well. Beer and wine, has to be cold. Tick.
Have 600ah house bank. Works fine.
Have 200Watt of solar but will increase to 400 -500 watt this winter.
Have a small 12V socket inverter for odds and sods.
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Old 13-08-2016, 15:47   #21
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Re: House hold refrigerator off inverter

yes there is a bloke running a large fridge from a 5 hp Honda with75 amp alternator hooked to a small battery with 1500 what inverter conected/ its an independent beer fridge .
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Old 13-08-2016, 16:09   #22
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Re: House hold refrigerator off inverter

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Originally Posted by SV THIRD DAY View Post
Absolutely...
When we bought our current boat it came with the standard Dorm Refrigerator and for about 2yrs ran it through our inverter. But it's not the most efficient way to go. What I would recommend is taking the standard dorm refrigerator and replacing the 120v AC compressor with a more efficient 12c DC compressor. Then you can run it directly from your battery bank and not have to deal with the extra power loss of the inverter always running in the back ground.

What would a conversion like this cost?
Well once you have the dorm refrigerator, you would be looking at about $300 plus you would need to find someone to solder and vacuum it down and then add refrigerant.

There is still hope for the old Norge



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Old 13-08-2016, 18:27   #23
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Re: House hold refrigerator off inverter

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I've found that the issue using household refers is that they run too often because of the lack of box insulation. I purchased a Grape Solar 3.8cu ft. 12v /120v fridge and hooked it up through a 12v timer so that at night it only runs 20 minutes every three hours which solved my overnight battery drain. I too use two 8D's for my house bank but know from experience that I need them to stay out of the 11 volt range overnight if I'm going to get maximum life out of them. BTW, the Grape Solar fridge cost me $379.00. Uses 5.4 amps 12v so it's fairly effect entry to run. Please don't come at me with needing to switch to T 105's. I've already been there and done that, and get more bang for my buck from the 8D's, because I get the Deka's cheap. I also like having extra cranking amps if I need them which the T105's just don't have. My best mate owns Caribbean Battery.
I like the sound of the Grape Solar fridge. Any one know if they or anything similar are available in Australia?
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Old 13-08-2016, 21:20   #24
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Re: House hold refrigerator off inverter

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BTW, Has anyone ever pulled the tin off of a household fridge and isolated the compressor / condenser unit to allow for adding proper insulation to the box? I've been thinking that this could be done to make a household refer "keep it's cool better".
You can put your compressor anywhere you like , preferably someplace where you could use some extra heat or where the extra heat can be vented out. You can also put your condenser anywhere you like also . It will be putting out more heat than the compressor and you can even run condenser line through a line that has seawater flowing through it as a liquid cooled condenser. This can all be done with 3/16" 1/4" and 5/16" 3/8" soft copper refrigeration tubing . You can sweat the joints with a silfos (silver & phosphorous) stick. You need a new liquid line drier and a good vacuuming with a deep vacuum pump before you charge it up.New fridges these days don't use much power these days. A 14 cu ft standard kitchen fridge uses as low as 80 watts and run time is relative to how fast heat leaks back into your fridge which can also be reduced buy adding closed cell foam insulation to the outer walls and then wrap it with reflective foil bubble wrap with the reflective side facing out. With these tricks you could possibly have your fridge eating 30 watts based on continuous averaging or less once you do the math. The only hard part is finding a good vacuum pump ($400.00)and an acetylene MC tank and torch ($400.00). You could use propane to charge the fridge. Its a better refrigerant than refrigerant. You can use those cans you buy at the hardware store to recharge your auto Air-conditioning is mostly propane.Half a can ( 4 oz ) is plenty for a 14 cu ft fridge. Also the sizes of the tubing is important. Suction could use 3/8" and the condenser lines 3/16". Unfortunately it does take some skill and knowledge to do this kind of work so I recommend you hire someone who is good with a torch so they don't burn your boat down. Safety First.
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Old 14-08-2016, 02:46   #25
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Re: House hold refrigerator off inverter

Hmm I think it is possible to get the materials for a self made top load fridge for below USD 200 and the cooling unit and condenser for about 700 USD.

I was stupid and bought the insulation materials for 1200 USD to have the best ones. That was stupid... 5 cm of styrofoam and 2mm of white painted aluminium on the inside does the same job.

Remember: 140l 50/50 freezer/fridge with 1,6Ah = 38,4 A/24hrs
2,6 m of solar panels give me 10Amps during the day = 80A/8hrs

and the cooling unit is a fire and forget job.
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Old 14-08-2016, 02:57   #26
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House hold refrigerator off inverter

Getting very good power consumption results from a mid sized LG household fridge (300 litres) which has been retrofitted with a Danfoss db50 (around 20 years old now). Would like to turn the fridge on its back when I remodel the galley, don't like the way the cold air (and fridge contents) spills out when you open the door. But overall, from observing this setup I would be tempted to try a mains voltage version on an inverter should the Danfoss ever die. It is surprisingly efficient.


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Old 14-08-2016, 09:42   #27
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Re: House hold refrigerator off inverter

surprised that the inverter lasts that long...had inverters down as "nice-but-fragile-&-soon-dead-when-aboard"
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Old 14-08-2016, 10:43   #28
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Re: House hold refrigerator off inverter

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Originally Posted by meridian28 View Post
Since everyone has different size reefers I think we should start looking at amps per cubic foot to get a better understanding of efficiency.
Good idea.

So moseriw has a 140 liter WAECO fridge consuming 460 watts per day which works out to 96 watts per cubic foot per day.

A typical household A+++ rated fridge of 340 liters consumes an average of 0.4 kwhr per day. Works out to 32 watts per cubic foot per day.

Super insulating the walls and back is no longer relevant since that is how the units cool themselves. Energy losses through the walls are not so great anyway. It is through opening the door.
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Old 14-08-2016, 13:20   #29
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Re: House hold refrigerator off inverter

Wrapping the fridge with the condenser makes the fridge inside effectively believe it's sitting a 140 Degree room (not good). Good thing less than 1% of fridges are designed this way. Most fridges (domestic) have a condenser that is coiled up so a small fan can blow the heat out of it. ( Not good in a boat. it would become a blast furnace in short time. 1,200.00 for insulation ?? were you going to insulate the whole boat ? There's nothing wrong with using a little 24" X 24" X 36"tall Freezer with a VB-7 beverage cooler control to make it operate at fridge temperatures.You may want to look for one with a though the floor drain (most have) make three layers of baskets for easy access to you food below. Most used food in top basket , the rest below just beer. Condenser and compressor can be located anywhere on the boat.
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Old 14-08-2016, 14:25   #30
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Re: House hold refrigerator off inverter

If you have a lid instead of a door then your cold air will stay inside instead of falling out on to the floor. Then the only thing you need to reduce energy loss is to have a near perfect as possible a vapour proof gasket. Plus every time you open the lid you will have a complete gas (water vapour)exchange due to all gasses in the atmosphere having pressure independent of each other (Diffusion) whether it's for two seconds or two minutes which means that water vapour uses energy to condense inside the fridge. Remember condensing releases heat always. Always try to reduce the number of times you open the lid not how long you keep it open unless you have a door. Vapour barrier should be pin hole perfect and on the warm side of the wall (outside for fridges) The whole goal is to reduce the rate of heat penetrating the walls and lid while you pump heat out with the compressor.
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