Portable Fridge Freezers.

[geem]

I'm married, of course I have a fridge at home. I see it as a waste of energy as we shop in the French style. Buy stuff and eat it that day.

Really can't see anybody needing a fridge in the UK as few people are away from a shop for more then three days. If you are the change what you eat and drink. UHT milk keeps for weeks and once opened is usually consumed in 24 hours.

So you have time to shop every day? I guess you live near shops. Not everybody does. Just going backwards and forwards to the shops every day would cost us a fortune in petrol when we are back at home. On the boat, living aboard, the fridge and freezer are essential. We often don't get near shops for several days if not weeks. On ocean pasages, we allow for 1 months worth of food. We care about our diet we try not to eat ultra processed food. It's incredibly hard to do that without fresh produce. The fridge is very important to us. So much so that I carry refrigerant and a vacuum pump onboard.

 

[Neeves]

I'm married, of course I have a fridge at home. I see it as a waste of energy as we shop in the French style. Buy stuff and eat it that day.

Really can't see anybody needing a fridge in the UK as few people are away from a shop for more then three days. If you are the change what you eat and drink. UHT milk keeps for weeks and once opened is usually consumed in 24 hours.

I think you will find that most people in France have a fridge.

So you use a mobile phone, happy to use GPS but reject refridgeration. One reason for the existence of supermarkets (and the death of the greengrocer, butcher and fishmonger) was the idea you could visit one retail outlet (the supermarket) and buy your week's worth of supplies in one hit, take it home and store the more delicate items ....greens, fish, soft fruit - in your fridge

We go to Tasmania for 3 months, its climate is not so different to the UK. We focus on SW Tasmania, Port Davey where the nearest supermarket and road are 100nm away. We catch crayfish, once we caught 13 overnight On the way to SW Tas we catch tuna. We could live off baked beans and Fray Bentos pies but technology now allows us, and anyone, to buy a small fridge and freezer and ones diet can be almost identical to someone who visits the supermarket daily. Basically to be without a fridge in Tas (or crossing an ocean) would mean returning to the sort of diet common in an 18th Century square rigger, salt pork, beef or fish, bottled lemon juice and rancid water.

This thread was initiated to take account of one of the most recent introduced technologies, Lithium batteries, and apply its use to a domestic fridge - the unknown is:

Is a small domestic 240v fridge more efficient than a 'dedicated' small 12v fridge specifically sold, expensively, for yachts (and motor homes)?

Jonathan

 

[William_H]

What is plain from this post is that every one's needs and habits are different regarding fridge and freezer. Yes you can do with out. Yes you can enjoy cold stuff fpr a short time with just an insulated box and ice. Newbees to this cruising thing might well start with ice in a box and let experience tell them way to go. ol'will

 

[harvey38]

What is plain from this post is that every one's needs and habits are different regarding fridge and freezer. Yes you can do with out

What??????

Sorry but I have to have ice in my Bacardi and Coke

 

[Refueler]

I like my Full English in the morning and having suffered lack of during cruises ... I wanted to sort that out. The Vevor Freezer / Fridge did just that along with making sure my local beer was drinkable.
I mentioned before that I have a Coolbox ... about 30 - 40lt .... that draws too many amps to be on continuous - so that has a relay that clicks in when engine runs. The Vevor set to freezer .... so the two together provide good combo.

The new boat has built in fridge - so the Vevor can still do its Freezer duty and feed the built in unit.

Purely a suggestion ... to OP if you get a Fridge / Freezer box ... then consider getting a soft insulated bag that's used for camping / BBQ's .... that can fold away when not in use - but can be your cold bag to let items remain for a time / defrost ready to be used. I have 3 of them ... two are about 30lt and third is designed around 6 standard Coke / Beer cans !!

 

[B27]

What??????

Sorry but I have to have ice in my Bacardi and Coke

What we sometimes used to do was buy a big bag of ice cubes from a supermarket, put some in a Thermos, have a bucket of melting ice in a coolbox.

As well as cheap compressor fridge/freezer/coolboxes, there is scope for better 'passive cool boxes', the expensive Coleman etc ones are pretty good, you could build-in something with modern insulation like Celotex.

A slippery slope to re-designing your boats interior maybe?

 

[B27]

..... the unknown is:

Is a small domestic 240v fridge more efficient than a 'dedicated' small 12v fridge specifically sold, expensively, for yachts (and motor homes)?

Jonathan

I think not (possibly depends on your definition of 'efficient'!!!)

I ran our portable 12V camping cool box/fridge/freezer similar to Refueller's Vevor unit at home using an energy monitor, it used less than 150Wh per day,IIRC I set it to 2degC with a couple of 2 litre water bottles in it.
The claimed performance of a tabletop fridge is about twice that. But that table top fridge will have more capacity... So it's 'efficiency' in Ah per cold beer might be better.

It's all about insulation. A domestic fridge is a big box with fairly thin walls, so the insulation is not that great. You want a smaller box and/or thicker walls.
A cold store built into the hull could have good thick walls. Like 150mm of PIR e.g. Celotex.

The actual 'efficiency' of a compressor fridge will be something like pumping out 3 or 4 times the electical input. That will be affected by the ability to lose the heat, ie. using a noisy fan or not, water cooling. But the heat pump fundamental will be similar.

What I have seems to be about the minimum plausible Ah, for a pretty much 'drop in' solution. I bought it, modified the previous owner's coolbox holder, job done.
Anything else would have implied serious woodwork and more Ah, but might hold more beer.

Also I'd need a better inverter so the £100 table top fridge becomes roughly the cost of a 12V coolbox type.

Other people are starting from different places, long distance yachts with more space, sophisticated electrics, unlimited solar etc.
Different aspirations too!

 

[geem]

I think not (possibly depends on your definition of 'efficient'!!!)

I ran our portable 12V camping cool box/fridge/freezer similar to Refueller's Vevor unit at home using an energy monitor, it used less than 150Wh per day,IIRC I set it to 2degC with a couple of 2 litre water bottles in it.
The claimed performance of a tabletop fridge is about twice that. But that table top fridge will have more capacity... So it's 'efficiency' in Ah per cold beer might be better.

It's all about insulation. A domestic fridge is a big box with fairly thin walls, so the insulation is not that great. You want a smaller box and/or thicker walls.
A cold store built into the hull could have good thick walls. Like 150mm of PIR e.g. Celotex.

The actual 'efficiency' of a compressor fridge will be something like pumping out 3 or 4 times the electical input. That will be affected by the ability to lose the heat, ie. using a noisy fan or not, water cooling. But the heat pump fundamental will be similar.

What I have seems to be about the minimum plausible Ah, for a pretty much 'drop in' solution. I bought it, modified the previous owner's coolbox holder, job done.
Anything else would have implied serious woodwork and more Ah, but might hold more beer.

Also I'd need a better inverter so the £100 table top fridge becomes roughly the cost of a 12V coolbox type.

Other people are starting from different places, long distance yachts with more space, sophisticated electrics, unlimited solar etc.
Different aspirations too!

Running an inverter from 12v to 220v to run a 220v fridge has its own inefficiency. Circa 10% losses on a good quality inverter. More like 20% on a cheapy in my experience.
COP on fridges is typically 2.5:1 maybe 3:1 if the condensing temperature is lower enough. If you are UK based where the sea temperature is generally excruciatingly cold, the water cooled condenser will squeeze some extra efficiency out of the system. Not so in the Caribbean where sea water and air temperature are often the same, currently around 30degC.
Small fridges, whether dedicated 12/24v types or 220v, all use the same tech. There is no magical difference thst will improve the COP. Insulation and reduced condensing temperatures are the only things that improve performance.

 

[B27]

Running an inverter from 12v to 220v to run a 220v fridge has its own inefficiency. Circa 10% losses on a good quality inverter. More like 20% on a cheapy in my experience.
COP on fridges is typically 2.5:1 maybe 3:1 if the condensing temperature is lower enough. If you are UK based where the sea temperature is generally excruciatingly cold, the water cooled condenser will squeeze some extra efficiency out of the system. Not so in the Caribbean where sea water and air temperature are often the same, currently around 30degC.
Small fridges, whether dedicated 12/24v types or 220v, all use the same tech. There is no magical difference thst will improve the COP. Insulation and reduced condensing temperatures are the only things that improve performance.

All good points.
I think the COP will vary also between a fridge and a freezer. It is what it is, and the actual number only matters if you are doing the maths for a celotex coolbox or something.

I have not dismantled a modern 12V fridge, but the old ones were doing some power conversion to drive a sealed AC motor, so there may be some conversion inefficiency in a 12V type too.

Bottom line is I can have (a modest amount of) cool fresh food (and beer) for about 1 amp. (average). Probably a bit less.
I get the first day for free loading with a frozen chilli among the mix of food.
24Ah per day is do-able with the leisure battery I have, £50 worth of solar panels and minimal motoring.

Worth considering for anyone doing modest cruising on a small simple boat IMHO.

 

[geem]

All good points.
I think the COP will vary also between a fridge and a freezer. It is what it is, and the actual number only matters if you are doing the maths for a celotex coolbox or something.

I have not dismantled a modern 12V fridge, but the old ones were doing some power conversion to drive a sealed AC motor, so there may be some conversion inefficiency in a 12V type too.

Bottom line is I can have (a modest amount of) cool fresh food (and beer) for about 1 amp. (average). Probably a bit less.
I get the first day for free loading with a frozen chilli among the mix of food.
24Ah per day is do-able with the leisure battery I have, £50 worth of solar panels and minimal motoring.

Worth considering for anyone doing modest cruising on a small simple boat IMHO.

Just about all small12v fridges these days use Danfoss compressors. Now called Secop. They are 12v or 24v. The COP doesn't change if its a freezer. It's still 10w of power for 25w of cooling. You just need more cooling to freeze so you use more power by running the compressor for longer.
On our old boat, with water cooled condenser, our 100L fridge freezer used about 1amp average at 12v in cold UK waters. It was well insulated.

 

[Refueler]

The fridge unit built in on my latest boat will drain the domestic battery of course over time - previous owner had a solar panel added with controller ... its not big - I reckon about 20 - 30W size .. so its output averaghe is probably 10+W ... and according to him - it managed to cope with the fridge set on moderate cooling ... if he left boat for just a few days.
But I have to say - he did show that he carried a spare unconnected battery under the nav seat for en=mergency's. Why I don't know as the Engine start battery is separate anyway -- charged also by the solar but does not feed domestic.

 

[QBhoy]

Can’t recommend highly enough…the excellent weaco/dometic CF range. I’ve the small CF11 model. It’s likely surpassed an easy 1000 hours of hard use to far. So efficient and effective. Can freeze down to -18 too, should it be required.
Whatever you decide…absolutely needs to be a compressor unit, as you’ll no doubt know already.

 

[Refueler]

Owner long term review ...

I have had my Vevor plugged in and continuous in the house while boat repairs going on ... basically to see if it keeps going. Not a hint of anything going wrong ... that's more than a month now ... of non stop ...

 

[geem]

Can’t recommend highly enough…the excellent weaco/dometic CF range. I’ve the small CF11 model. It’s likely surpassed an easy 1000 hours of hard use to far. So efficient and effective. Can freeze down to -18 too, should it be required.
Whatever you decide…absolutely needs to be a compressor unit, as you’ll no doubt know already.

Our Indel B portable, has been used full time for 9 months out of 12 months for 4 years and then continuesly for the last 12 months. I make that 35000 hours of use. The insides are all Secop compressors regardless of the badge on the front.
The inbuilt Danfoss compressor fridge has been in for the last 11 years on a similar usesage basis

 

[Neeves]

Running an inverter from 12v to 220v to run a 220v fridge has its own inefficiency. Circa 10% losses on a good quality inverter. More like 20% on a cheapy in my experience.
COP on fridges is typically 2.5:1 maybe 3:1 if the condensing temperature is lower enough. If you are UK based where the sea temperature is generally excruciatingly cold, the water cooled condenser will squeeze some extra efficiency out of the system. Not so in the Caribbean where sea water and air temperature are often the same, currently around 30degC.
Small fridges, whether dedicated 12/24v types or 220v, all use the same tech. There is no magical difference thst will improve the COP. Insulation and reduced condensing temperatures are the only things that improve performance.

I didn't 'quite' understand this, can you clarify?

It refers to my thread on changes in usage of power on a yacht. We now can have Lithium as our storage unit and can have an all electric yacht, no gas, and the galley can be all 240v (with an inverter). Power, weather dependent, can be all solar with a bit from the alternator if you do some motoring

So if you are running the inverter anyway are the losses to which you refer the losses to simply run an inverter, so shared by all the 240v units, including the fridge, or are the losses cumulative, the more units you have the more losses at the inverter.

From the rest of the discussions it seems domestic fridges are no better nor worse than the units commonly sold for yachts (though the upfront costs of the domestic fridge might be lower, off set by the inconvenience - its not going to fit a standard space).

Basically the only thing to improve 'any' fridge is remove the warm air from the compressor and feed as cool air (or water) as possible to the same compressor.

Jonathan

 

[geem]

I didn't 'quite' understand this, can you clarify?

It refers to my thread on changes in usage of power on a yacht. We now can have Lithium as our storage unit and can have an all electric yacht, no gas, and the galley can be all 240v (with an inverter). Power, weather dependent, can be all solar with a bit from the alternator if you do some motoring

So if you are running the inverter anyway are the losses to which you refer the losses to simply run an inverter, so shared by all the 240v units, including the fridge, or are the losses cumulative, the more units you have the more losses at the inverter.

From the rest of the discussions it seems domestic fridges are no better nor worse than the units commonly sold for yachts (though the upfront costs of the domestic fridge might be lower, off set by the inconvenience - its not going to fit a standard space).

Basically the only thing to improve 'any' fridge is remove the warm air from the compressor and feed as cool air (or water) as possible to the same compressor.

Jonathan

We turn our inverter on to cook or run the watermaker or make hot water. This accounts for maybe 1.5hrs per day. Running a fridge needs the inverter to be on 24/7/365. Power losses are generally higher in larger inverter. Running a 220v fridge needs an inverter. The daily loses from the inverter will be considerable. The loses from the inverter are there even when it is on but the fridge isn't running. With a 12v fridge, theere is no load when the fridge is off.

 

[Neeves]

We turn our inverter on to cook or run the watermaker or make hot water. This accounts for maybe 1.5hrs per day. Running a fridge needs the inverter to be on 24/7/365. Power losses are generally higher in larger inverter. Running a 220v fridge needs an inverter. The daily loses from the inverter will be considerable. The loses from the inverter are there even when it is on but the fridge isn't running. With a 12v fridge, theere is no load when the fridge is off.

We run our inverter, currently, as you do. When we need 240v we switch it on, and off when we don't need it. The reasoning is simple - currently our 240v requirements are insignificant - unless I get an angle grinder out . The reason to switch the inverter off is equally simple, from memory it uses 1amp/hr (Victron inverter/charger) and if you don't need 240v then 1 amp is significant.

Now if we had a 240v galley, 240v fridge and (as we currently do) a separate freezer, 240v desal that 1 amp is spread over lots of units, kettle, toaster, bread maker, induction stove and if the inverter could be switched on and off when the fridge and freezers cut in the 24 amps per day would be reduced and shared over lots of units - or is the inverter 'loss' more than the 1 amp/hr?

If I'm chasing an impossible dream then we are all condemned to buying 12v fridges and 240v induction stoves, domestic microwaves and electric kettle - and an inverter we use part time.

Part of my thought process was that a 240v might be a cheaper buy and more efficient to run (the latter seems to be incorrect)

I recall the 1 amp/hr from memory - which may be jaded

Jonathan

 

[geem]

We run our inverter, currently, as you do. When we need 240v we switch it on, and off when we don't need it. The reasoning is simple - currently our 240v requirements are insignificant - unless I get an angle grinder out . The reason to switch the inverter off is equally simple, from memory it uses 1amp/hr (Victron inverter/charger) and if you don't need 240v then 1 amp is significant.

Now if we had a 240v galley, 240v fridge and (as we currently do) a separate freezer, 240v desal that 1 amp is spread over lots of units, kettle, toaster, bread maker, induction stove and if the inverter could be switched on and off when the fridge and freezers cut in the 24 amps per day would be reduced and shared over lots of units - or is the inverter 'loss' more than the 1 amp/hr?

If I'm chasing an impossible dream then we are all condemned to buying 12v fridges and 240v induction stoves, domestic microwaves and electric kettle - and an inverter we use part time.

I recall the 1 amp/hr from memory - which may be jaded

Jonathan

To run a good sized watermaker we need a 3000w inverter. The standing loses on our inverter are way more than 1A. Even so, 24Ah daily is not inconsiderable for many people. There was a guy on the forum recently who said that was his daily load for his lithium. Our average daily load on the battery is 230Ah. Today we harvested over 4kw of solar but we use it all up running electric cooking, fridges, making water and hot water. The extra burden of an inverter on 24/7 makes no sense to me.

 

[Neeves]

Geem,

Thanks

You do underline one of my beliefs - it does not matter how much solar you can produce but your consumption will grow to slightly exceed production.

Just a variant on Parkinson's Law:

"work expands to fill the time allotted for its completion".

 

[Refueler]

Geem,

Thanks

You do underline one of my beliefs - it does not matter how much solar you can produce but your consumption will grow to slightly exceed production.

Just a variant on Parkinson's Law:

"work expands to fill the time allotted for its completion".

Its same as salary .... its very easy to increase expenditure without realising - meaning still with little to spare !!