Refrigerators and Freezers

The efficiency best, as I understand it is Frost King. Expensive though
I have 2 swing door Engles and a lift door that is designated freezer. The insulation is very lacking but the electrical efficiency is great. Been going 4 years, non stop.
I really like the fact that they are stand alone from solar/batteries only, less cloudy days. On long nights I may have to give a genset boost before bed but on a 50-50 dark-light day I wake up to 70 to 75% left in the batteries. I have 720 watts of solar and 1135 amps @ 20 hours of battery bank. 10 Golf Cart 6 volt. Need more batteries but alas, no room. Day break to float is before noon.
All that being said, I think the inverter to Frost King might be the best way to go with a robust solar-battery set up.

Simi 60 said:

And yet here I am with a boat full of domestic refrigeration and haven't been in a marina in two years.

Of course you do make a point about leaving the boat unintended for any length of time.
If there is no sun the batteries will go flat without someone firing up the genset though I suspect even with a 12v system, the same laws of physics will apply.

Reality is that if we had to leave the boat for any more than 48 hours we'd be putting her in a marina anyway so problem sorted.

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Of course I agree with most all above with the exception of having to run a genny if without sun for a few days. There are exceptions.

First is whether the only load on the batteries is the refrigeration system and how much solar is onboard. I find that even in rain, I get some charge from my solar (1180 watts). There is illumance present even in rain. My anchoring experience is to run our genny about an hour or so both in the mornings and evenings for meals that include morning coffee. Last year I had genny problems and relied entirely on solar to recharge.

Our load includes a 3kw true sine wave inverter that runs continuously although the fridge is powered by controls that forces it to use genny/dock power when available. Also we have two 32” HDTVs, one that seems to operate almost all day and night, microwave oven, lights and so forth.

Our fridge is a Summit 8.3cuft beauty that unfortunately is no longer made. I don’t know what I can replace it with if it should fail but so far it is entering its 11th year of life on our boat. The freezer keeps ice cream rock hard. The self defrost is a God send along with an interior light. But this I do know, if it should fail, I will never ever consider using an expensive so called marine fridge. Fridge selection as we all know is a matter of personal choice.

Mule said:

The efficiency best, as I understand it is Frost King. Expensive though

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???

Links please?

foggysail said:

Of course I agree with most all above with the exception of having to run a genny if without sun for a few days. There are exceptions.

First is whether the only load on the batteries is the refrigeration system and how much solar is onboard.

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Just running refrigeration only, we could probably run near indefinitely on solar even in winter.

Add the 180 litre 240v hot water system in which pulls 70ish amps for 1.5 hours a day going from on average, 52c to 60c, and all bets are off.

In summer, we can run that HWS on solar as well, we just wait until about 10am before hitting the switch hen we are now at around 93% SOC and have between 60 and 80 amps coming in from the panels.
Its done by 11:30sh and batteries will be at 100% about 1 hour later.

I will never ever consider using an expensive so called marine fridge. Fridge selection as we all know is a matter of personal choice

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No argument there.

Simi 60 said:

Just running refrigeration only, we could probably run near indefinitely on solar even in winter.

Add the 180 litre 240v hot water system in which pulls 70ish amps for 1.5 hours a day going from on average, 52c to 60c, and all bets are off.

In summer, we can run that HWS on solar as well, we just wait until about 10am before hitting the switch hen we are now at around 93% SOC and have between 60 and 80 amps coming in from the panels.
Its done by 11:30sh and batteries will be at 100% about 1 hour later.


No argument there.

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WOW!!! You have a very impressive system and we both appear to firmly agree on domestic refrigeration use.

How large is your solar installation? I thought with my puny 1180 watt panels could hit my MTTP's current limit, 70 amperes. So far my maximum charge current is in the low 60 range. I need to increase a wire size on a short link from the controller to the #2 copper wire battery feeder. I am certain because the wire, about 3' gets hot with high charging currents or run a separate wire pair from the batteries to the controller to read the correct voltage without wire drops.

9 x 250w (2250w) Jinko panels set as 3x3
1 midnite classic 150 mppt
1 victron 5000va/120amp inverter charger (original victron 60amp charger on standby as spare)
8 x 220ah 12v batts wired up as 24v

Have space up there for 3 more panels fwd of the funnel or aft on the stainless steel frame but would need another smaller mppt as well.

For everyone claiming one type of fridge is more efficient than another, can you quote some numbers? Some may be misled by the amp rating. That number is useful only to determine the appropriate size wire. The only way to determine total energy consumed is to test a fridge over several days with a device which measures total KWH.

A few months ago I tested our 11year old GE 15.5 cu ft fridge with a Kill-a-Watt, and found that it used 1.7 kwh/day. Our inverter is 90% efficient, so our fridge uses 1.9 kwh/day from the batteries. This amount includes the freezer portion, the automatic defrost, and the interior light.
I then looked at the EnergyStar rating (www.energystar.gov) for a new fridge equivalent, and found GTE16GSHSS had an EnergyStar rating of 1.17 KWH/day, or about 40% more efficient than our 11 year old version. One other thing I noticed from the EnergyStar ratings is that the amount of energy consumed is in direct proportion to the size of the fridge. Smaller fridges use proportionately less.
I could not find any EnergyStar ratings for 12V or dual voltage fridges. EnergyStar is a voluntary program so no manufacturer is compelled to submit their equipment for testing.
Can anyone give a link to energy ratings for "marine" fridges.

Arguing what is the best kind and size of fridge is like arguing what is the best kind of boat. It depends on your lifestyle, and where you cruise. For us, we will stick with our old 120V AC fridge. But if it craps out we will not spend much on repairs. Instead we will replace it with a new more efficient 120V AC model.

Simi 60 said:

9 x 250w (2250w) Jinko panels set as 3x3
1 midnite classic 150 mppt
1 victron 5000va/120amp inverter charger (original victron 60amp charger on standby as spare)
8 x 220ah 12v batts wired up as 24v

Have space up there for 3 more panels fwd of the funnel or aft on the stainless steel frame but would need another smaller mppt as well.

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You are well equipped!!! Nice job!

The really efficient AC fridges are 240V, sold in more developed markets where energy efficiency is a much higher regulatory priority than in the "free-market" US.

I have rarely used over 40AH per day with any 12V compressor fridge, except when in freezer mode or over 85-90°F ambient temps.

And that's with OTS portables with poor insulation. Proper custom marine installs with 4" foam can average less than that with spillover dual use and double the cu.ft. capacity, and eutectic holding plate designs can basically run off otherwise unused "excess" power, not use much battery energy at all.

But on a trawler, few are going to care about that level of engineering just to save AH, household appliances are so cheap, you've more room than sailboats for panels, and / or the big engines' right there. . .

AC/DC marine refers way overrated. One of my best days was when I replaced my cranky Norcold with a $300 Hotpoint. Add an inverter and you have AC/DC. That's essentially all the Norcold does. Ym

"The efficiency best, as I understand it is Frost King. Expensive though"

You might compare it with Sunfrost , built for off grid operation.

Sun Frost: Energy Efficient Refrigerators, Freezers, and Sustainable ...

Energy Efficient Refrigerators, Freezers, and Sustainable Living Products - Sun Frost


Sun Frost: worlds most energy efficient refrigerators and sustainable living products. Including composters, solar vaccine refrigerators and composting toilets.

Most of the hassle of refrigeration power use comes from the desire to use an off the shelf unit.

In past times the refrigeration was built into the vessel , so massive 4-6 inch insulation helped and large eutetic engine driven systems could capture many HP of energy in a short period of time.

For a dedicated cruiser that prefers silence to noisemakers , it is still an option.

Ya got me FF, I misspoke..... I meant Sun Frost. A brand you pointed out to me sometime back.

On boats with lots of power available on demand

it is an entirely different conversation compared to those camping on the hook for months at a time without burning any dino juice.

The latter group is willing to sacrifice space to get down below 40AH per day at 12V.

The former can afford to think in kWH and want all the comforts of home.

It is true that the modern super-efficient 240AC units available in the non-US more-developed world can get **almost** as efficient even with inverter losses as the 12V Danfoss type portable units or sailboat-style custom jobs.

But the latter have the efficiency advantage of a custom box which can be super-insulated, makes a huge difference. But at a higher cost.

john61ct said:

It is true that the modern super-efficient 240AC units available in the non-US more-developed world can get **almost** as efficient even with inverter losses as the 12V Danfoss type portable units or sailboat-style custom jobs.

But the latter have the efficiency advantage of a custom box which can be super-insulated, makes a huge difference. But at a higher cost.

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There was another thread, either on this or Cruisersforum, and we contributed numbers for actual energy usage. I recall that the high efficiency household units (plus inverter) were more efficient than the old-technology Danfoss types.

When I measured from my other villa, the refer (12-14 cf roughly) was consuming 500 watts daily. Digital inverter technology. So that works out to about 42 amp-hrs per day at 12 vDC. But the temperatures here are probably more extreme than in a boat since we don't run the aircon when away from home - the kitchen gets really hot during summer where outside temps are 125-130 degrees.

Cost wise a custom built marine unit is generally more expensive as well, as you mentioned above.

Of course many boats cannot accommodate a household unit.

"Of course many boats cannot accommodate a household unit."

However the RV or Amish style ( Servelle) propane fridges solve all the problems.

A single 20# tank will keep a large home sized reefer cold for a month , in silence.

Even cokling with the reefer supply does not seem to matter much to gas consumption.

A safe well engineered propane system can be done .

On out launch the unit is simply mounted in the cockpit, which is self draining.

Its a lot less of a PIA to need to go outside to get the food,. drink, ice and ice cream than have a noisemaker , batterys by the dozen , and an expensive complex system to maintain.

Our goal is always to cruise with the least hassle . the reefer /cooking hassle is easily solved with propane.

RV sized Propane refrigerator freezers will burn a 20# tank of propane in 10 days in hot humid weather. Engineers from Dometic said to expect 1.4 to 2.1 pounds per day depending on temp/humidity.

Here is a good discussion on the merits of propane fridges vs electric.

Off Grid Refrigeration: Solar Electric Vs Propane | Sun Frost Blog

I recognize that there are problems with some of the data on Sunfrost's web site, but the principal is accurate.

The scariest problem I saw on their Website were the prices....Holy Cow!

meridian said:

RV sized Propane refrigerator freezers will burn a 20# tank of propane in 10 days in hot humid weather. Engineers from Dometic said to expect 1.4 to 2.1 pounds per day depending on temp/humidity.

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And around here, your 20# tank will be "filled" to only around 15#s.

Yes it is "possible" for propane to be safely used inside the living space on boats.

Some men are willing to live and work for decades on nuclear subs too.

Not me.

When an efficient $600 Engel and $400 worth of solar will do the trick.

I like the propane refer idea, but consuming that much gas only is practical if you live a “steady” life. For those cruising various countries then there will be difficulties with refilling.

I’m impressed by the guys here with large solar arrays who can provide almost 100% of their electric needs cleanly (not including aircon of course).

"RV sized Propane refrigerator freezers will burn a 20# tank of propane in 10 days in hot humid weather."

Ours has been in use for a decade , and worst case is 18 days in Fl sun .

It sits on the aft deck in a ply box with zero added insulation.

A couple of inches of insulation , or a sun shade would help matters a lot.

The newest RV units can be double sized from the older units .

Servelle sez,

The Dometic Servel RGE400 Refrigerator serves its purpose in longevity. Even in hot climates, this Dometic Servel RGE400 will freeze popsicles and pass the 'ice cream test'. This finely crafted appliances operate on either propane, at the rate of about 1.8 Gals per week (7.7 pounds), or standard backup power of 120 volt AC. Run out of propane and this standard feature will power up the fridge at about 325 watt generator pull.

https://bensdiscountsupply.com/propane-refrigerator/medium-size-propane-refrigerators-6-15-cu-ft/

The 6 & 8 cubic ft models use less gas than the 15 cubic ft units/

I had a kerozene fridge and freezer on my sailboat. Worked well but used about 10 liters (2.5 gallons)a week in the tropics.
I have a multi fuel in my 5th wheel, uses about 30 lbs of propane a month if gas only.
On the boat, I had a Vitrifrigo (10 cu.in.) that quit recently. I replaced it with a Walmart style unit of the same size but first tested electric consumption as I had done with the Vitrifrigo.
Surprise, measured over one week, same place, same temp. outside and inside, the watt meter averaged about 480 W/day for each. The Vitrifrigo needed exactly the same energy than the cheap one! The cheap one runs on the inverter, so we can add 10% for efficiency loss but it is still a good deal.I know it may not last as long but I can buy 12 units for the price of the marine unit.