# Most efficient fridge on the planet !!



## oldtech

..... thought that might get your attention !  c:

Hi Campers !

I *really* want a 12 volt compressor fridge with low power consumption.
Waeco do some cracking ones ..... if you want to spend six hundred squid ( or more ! ).

I've been doing lots of research on this topic recently.
You can quite easily turn a chest freezer ( an old one will do ) into a fridge with some very basic wiring changes 
..... low voltage wiring as well , no need to mess with the mains supply.

I Googled "* Convert a freezer to a fridge "* and also did the same on YouTube.
There are some very good articles around ,and also about using fridges with solar power ....
click these links for more info  :-

Solar-powered refrigerators by Jeffrey Yago, P.E., CEM Issue #102

Chest Freezer To Fridge Conversion-The Most Energy Efficient Fridge Ever | A Self Sufficient Life

Chest fridge

The big advantages appear to be that freezers are much better insulated than fridges , so the compressor is
running for much less time in any 24 hour period ... ( compressor OFF = ZERO power consumption ).
... AND ... with a "chest-fridge"  ,all your cold air doesn't come pouring out everytime you open the door.
As far as I can see , the only real disadvantage is that you might get damp build-up in the bottom of it.

Have any Wildcampers out there actually tried this ?

What about with 12 volt freezers  ( do such things actually exist ? ).
Please post a reply if you've had any experiences with this idea .

Thanks

Oldtech


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## watchthis

Hi Old tech
A very interesting subject Thank you for sharing.  I've always wondered whether it was possible to convert a 'work' top small freezer into a fridge it opens up some possibilities.  Many thanks
Bye for now 
Freddie:wave:


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## ivecotrucker

Thanks Oldtech, seems to be an idea worth considering. We are the not so happy owners of a £700+ Waeco compressor, almost the biggest single cost in our conversion. Lovely stainless steel job but it will eat a 330Ah battery bank in just over 72 hours (this one is a free replacement from Waeco (now Dometic), the first one was even worse). In our experience their claimed power consumption figures are far too optimistic, and we have it turned down to near minimal cooling. As you say, the insulation on a freezer seems much better. Please share your further experiences because our Waeco has got to go.


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## REC

Have you conisdered a gas fridge? they are cheaper to run but not sure of the logistics of fitting one. We saw several "dented but new" at a boat jumble last year & ex-caravan ones (which also run on 12v while the engine is running) can be picked up cheap (well cheaper than £700!!). We looked at 12v fridges previously and the cost put them out of our price bracket. Your idea makes sense..must be a way. Look forward to hearing how you got on.:cool1:


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## oldtech

ivecotrucker said:


> Thanks Oldtech, seems to be an idea worth considering. We are the not so happy owners of a £700+ Waeco compressor, almost the biggest single cost in our conversion. Lovely stainless steel job but it will eat a 330Ah battery bank in just over 72 hours (this one is a free replacement from Waeco (now Dometic), the first one was even worse). In our experience their claimed power consumption figures are far too optimistic, and we have it turned down to near minimal cooling. As you say, the insulation on a freezer seems much better. Please share your further experiences because our Waeco has got to go.



Hi Ivecotrucker
thanks for the reply .....* REALLY !
*
You may have saved me £700 !!!
I saw a Waeco compressor fridge advertised on here ( 2nd hand ) a few months ago , then I got called away
and forgot about it , and by the time I remembered a few weeks later and contacted the seller ..... it was sold.
I was kind of cursing myself for a long time afterwards as I've read some good things about them.
Makes me wonder now if the seller hadn't discovered the same issues as yourselves !!!
It sounds like they may only really be suitable for hooked-up on-site use ..... and that doesn't interest
me at all.

I'm determined to have a solar powered , nearly self-sufficient vehicle for long term wild-camping.
I'm going to look for a small 2nd hand chest freezer and do some experiments  " in me shed " .
You are dead right about manufactures claims for power consumption , probably the same as vehicle 
manufacturers claims for fuel ...ha ha.
In the States there's something called a "Kill-a-watt meter" which you plug your appliance into , just like
a time switch except that this logs the total power use over any period you choose... only $20 in the USA !!!
I keep seeing stuff about them on solar power forums .....I'm going to try and get one ..........  today !!
Anything positive to report and I'll put an update on this forum ....

In the meantime   "Happy Camping "

Oldtech

PS  just found a UK supplier !!   :dance:

£20 + p&p 

http://www.reuk.co.uk/Kill-a-Watt.htm


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## Firefox

I have seen loads of people try running compressor fridges. Unless you have a roof full of solar panels or a huge bank of batetries it all seems to end in tears. Even if you have 4 or 6 batteries, they will take a lot of charging. Unless the fridge is really tiny they are always going to have a fair current draw. And if lots of insulation you end up with smaller space. 3 way fridges are the way to go - gas is quite efficient.


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## Deleted member 22727

Hello.Just read this post,found it very intresting.So gas is the way to go unless hooked up.cheers.


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## AndyC

We have a Waeco MDC-110 fridge in our van. I must say it's a great fridge but it does use around 45Ah a day. Our 400Ah of batteries plus 160w of solar panels keep up with it in the summer but  we struggle if not on hookup in the winter, when we have to run the heating (Webasto Thermo 90) as well.

If you want optimum electrical power conservation you really need to go for a 3-way gas/12v/mains fridge. However I don't really like them because you have to be pretty level for them to work efficiently and there's those extra holes in the side of the van too.

AndyC


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## ivecotrucker

Thanks for the Thanks, Oldtech; glad to be of help. I guess you won't want any further info on compressor fridges but if you do then please contact me.
I have not heard of the "Kill-a-watt" meter so cannot comment reliably BUT will it also measure power consumption at only 12v ? Is the internal algorithm not set at 110v (for USA) or 235v (Europe-ish) ?.
Just a warning thought for you, I don't know the answer myself.


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## ivecotrucker

Hello AndyC,
That is an amazingly good advert for solar panels that a 160w panel can keep up with an MDC110 without running down your main bank.
Our decision to use a compressor was based on:

1) No holes in the side (& to maintain our semi-stealth external appearance)
2) Minimise dependence on noncompatible foreign gas bottles (now overcome by Gaslow type refillables)
3) Easier to install/remove/service without need for effective/safe gas flue sealing (I've seen some fairly   dodgy flue arrangements on some well known makes of campervan).
4) Minimise the amount of gas piping & number of unions
5) Better reliability if parked on a slope (but to be fair the '3 way' in our previous vehicle never once played up, even on the steepest of slopes)


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## Deleted member 2636

The biggest problem that I've experienced with 3 way fridges is that they are very sensitive to being absolutely level. The older ones were far worse that the more recent models. I've seen the figure of 5 degrees off vertical bandied about

They also suffer a loss of their cooling ability if the weather goes above a certain temperature; I'm not sur ehow much 30 degrees Centigrade or something like that. Dometic are well aware of this and even produce a supplimentry cooling fan for 3 way units.

The 12vDC comp units were originally designed for the Yotties as they never seem to be on an even keel. This was, until recently, a very small market as the majority of yachts didn't have room for a fridge. Now the Motorhome/Caravan/Barge people have also shown an interest the prices have come down marginally. Yachts also tend to carry a larger battery bank than Motorhomes or Caravans. They will tend to also have both wind gennys, engine alterantor and solar as a means of recharging

I've run both and have a 3way fridge freezer at present and I think it's useless compared to my previous 12v Comp units


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## oldtech

ivecotrucker said:


> Thanks for the Thanks, Oldtech; glad to be of help. I guess you won't want any further info on compressor fridges but if you do then please contact me.
> I have not heard of the "Kill-a-watt" meter so cannot comment reliably BUT will it also measure power consumption at only 12v ? Is the internal algorithm not set at 110v (for USA) or 235v (Europe-ish) ?.
> Just a warning thought for you, I don't know the answer myself.



Yeah , you are spot on there Ivecotrucker !
The UK version has a standard Brit 3 -pin plug on the back of the unit
and a Brit socket on the front to plug-in the appliance to be monitored.

There IS an effective , and relatively cheap meter to do the same for 12Volt DC.
I came across it while reading an American  solar energy Forum.
I noted down the link  ..... ( somewhere ... *  !!* )
If you want it , get back to me and I'll search for it.

If someone is using  solar panels + leisure batteries + inverter , then with the two monitoring systems 
together , you could do a* really *accurate analysis on your whole power system  ...... 
.... for relatively little cash outlay .... and it may pay for itself in energy savings.
Got to be better than changing appliances just because of *suspicions* about excessive power consumption !

Anyways , you clearly have your brain switched *ON*  .... always nice to see !!

All the best  

*OT*


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## ivecotrucker

Hello again Oldtech,
I am currently (!!) looking into Amp-Hour counters @ 12v so IF you find your info source please post it - but please don't spend hours looking for it.
Still got the 'Throw Over Inductance Coil' design on my drawing board (aka scrap of paper) - 
 a) how to launch it over an 80-100'+ high line ?
 b) how recover it ?
 c) how to measure the overhead HT voltage & hence calculate correct number of inductance turns ? 

If Benjamin Franklin harnessed a thunder cloud with a kite, some string & an old key (& lived to tell the tale) then I reckon my idea is a doddle. Perhaps I need a FLASH of inspiration ?.


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## oldtech

*DC Power Metering*



ivecotrucker said:


> Hello again Oldtech,
> I am currently (!!) looking into Amp-Hour counters @ 12v so IF you find your info source please post it - but please don't spend hours looking for it.
> Still got the 'Throw Over Inductance Coil' design on my drawing board (aka scrap of paper) -
> a) how to launch it over an 80-100'+ high line ?
> b) how recover it ?
> c) how to measure the overhead HT voltage & hence calculate correct number of inductance turns ?
> 
> If Benjamin Franklin harnessed a thunder cloud with a kite, some string & an old key (& lived to tell the tale) then I reckon my idea is a doddle. Perhaps I need a FLASH of inspiration ?.



*BINGO !*

I keep lists of websites / links that were interesting but didn't merit a bookmark of their own.....

..... the one I mentioned to you was in the second place I looked ...easy peasy !

DC Watt Hour Meter

RV & Marine Battery Monitor

It's an American site but I usually manage to find the same stuff in UK / Europe after a bit of searching...
eg the "Kill-a-watt" meter .... and I've found 3 similar devices for less money since I first mentioned it in a post .

Let me know how you get on ..

regards 

Oldtech


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## wildman

to save all the hunting, its available in the UK from ebay
Watt Meter & Power Analyzer /Watts up (Ver. 2) | eBay


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## ivecotrucker

Thanks to Oldtech & Wildman. 

Now, has anyone any ACTUAL experience of these gizmos, &, most importantly, how accurate are their 'predictions' of battery "State of Charge" & "Remaining Amp Hours" ?. There is quite a bit of guff available from manufacturers & retailers but also various comments that they don't work.

Your comments please Gentlemen.


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## oldtech

ivecotrucker said:


> Thanks to Oldtech & Wildman.
> 
> Now, has anyone any ACTUAL experience of these gizmos, &, most importantly, how accurate are their 'predictions' of battery "State of Charge" & "Remaining Amp Hours" ?. There is quite a bit of guff available from manufacturers & retailers but also various comments that they don't work.
> 
> Your comments please Gentlemen.



Hi Ivecotrucker

It might be worth starting a new thread to put your question ...  eg " Battery Power Monitoring"
It is a bit lost in here since the original thread title is about fridges.
I know the two things are related , I'm just thinking you may get more people reading it
and therefore more feedback ...

I would also like to hear other wildcampers experiences before rushing ( sort of ...ha ha !! )
to buy one 

.... just an idea :idea: 

*OT*


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## ivecotrucker

Be careful what your wife might wish for, Basildog. Some years ago we saw a fully plumbed in domestic clothes washing machine that the owner had installed in an otherwise bog standard white plastic motorhome.


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## windyjools

*Excellent thread!*

As per the title, so......I have identified the chest freezer that would do the job, found the black box, that will change the freezer into a fridge (I guess it is a change of ranges to the thermostat), BUT, how do you convert the damn thing to run from 12 volt?
I have previously run a domestic 240 volt fridge from an inverter, but it killed the (rather expensive 600 watt) inverter after a few weeks as the start-up power needed was overloading it! And the inverter takes quite a bit of power, so almost negates the savings in the more efficient insulation and cost-saving in buying a 240 volt chest fridge!!!!
Buying a full sine-wave inverter makes the whole thing eye-wateringly expensive.........
Is there a solution?......Apart from going three-way?


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## oldtech

windyjools said:


> As per the title, so......I have identified the chest freezer that would do the job, found the black box, that will change the freezer into a fridge (I guess it is a change of ranges to the thermostat), BUT, how do you convert the damn thing to run from 12 volt?
> I have previously run a domestic 240 volt fridge from an inverter, but it killed the (rather expensive 600 watt) inverter after a few weeks as the start-up power needed was overloading it! And the inverter takes quite a bit of power, so almost negates the savings in the more efficient insulation and cost-saving in buying a 240 volt chest fridge!!!!
> Buying a full sine-wave inverter makes the whole thing eye-wateringly expensive.........
> Is there a solution?......Apart from going three-way?



Hi Windyjools

Thanks for the post !

But please tell exactly what the " blackbox" is  that you are using.
The cheapest unit I have located in this country , that will do the job right  ,is over a hundred quid !
You need something that will switch the mains power to the fridge on and off according to the set temperature
in other words , a thermostat with a built-in mains relay and an external probe to go inside the fridge / freezer.
It gets a little more complicated because you really need a thermostat unit with TWO set points .... it should turn the
mains ON when the temperature hits the UPPER set point , and turn it OFF when it reaches the lower point....
..... and ideally these points should be 3 or 4 degrees apart.
If it doesn't work this way you will find that the damn thing is CONSTANTLY going on and off which will hurt both
the inverter AND the compressor in the fridge / freezer.

Secondly , you DON'T convert it to run off 12 volts , you keep it working on 240volt AC and use a suitable inverter.
Personally , I would be looking for an inverter with a bit more clout than 600 watts because the instantaneous "start-up"
current draw of the compressor can be quite high .... as with any device with an electric motor in it.
Keep an eye on this thread because it is an ongoing project , with several Wildcamping members working on it.
I have recently found a small chest freezer for £149

HAIER BD103GAA Chest Freezer | Laskys.com

If my calculations are correct , this unit should use about 470 watts *per day * *as a freezer*, and WAY less than that
if it was converted to a fridge as mentioned in earlier postings on here , and using a mains thermostat as described above.

Gas fridges are OK up to a point , but they have their drawbacks .... especially in hot climates.
Anyway , thanks again for your post ...
... regards

Oldtech


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## vwalan

is it really worth the bother .i use or did use an old electrolux fridge with a small freezer compartment . unfortunately its packed in now but a new fridge with a freeze box is only a hundred quid . i use a ring 2kw inverter .(ott i know .but it works other things if i want it too.).used to have 3 x80wt panels now 6x 80wt .and 600 or 800 amp of batteries . was using it for about 7 years till fridge packed up .mind it was old . waiting for a give away fridge . then off it will go again.


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## ivecotrucker

Thanks VWAlan. Do you know how much 12v juice your 2kw inverter used (excluding start up) if it was ONLY supplying your old Electrolux fridge please ?.


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## oldtech

*Full time living with solar power*



vwalan said:


> is it really worth the bother .i use or did use an old electrolux fridge with a small freezer compartment . unfortunately its packed in now but a new fridge with a freeze box is only a hundred quid . i use a ring 2kw inverter .(ott i know .but it works other things if i want it too.).used to have 3 x80wt panels now 6x 80wt .and 600 or 800 amp of batteries . was using it for about 7 years till fridge packed up .mind it was old . waiting for a give away fridge . then off it will go again.



Hi VWalan

thanks for the info.
That's quite a hefty supply of power you've got there !
If I remember right , you mentioned in earlier posts that you run power tools off this.

Is that a pure sine-wave inverter that you use ?
How long have you had it  , and would you recommend it to other Wildcampers ?
Have you used a 240 volt microwave with the inverter ?

Sorry to bombard you with questions but info from someone with your experience is priceless !! 
Especially to people who are wanting to build a solar powered system from scratch for "full-timing".
Thanks again

Oldtech


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## vwalan

hi its a  cheapy inverter. made by or sold by ring. i bought three from them about 7-8 years ago . two mates had the others .
 i have used a 240v micro wave off it but only a few times . thats when i am running the extension lead into the house. 
i run the household fridge in my trailer when away .plus lots of other things . tv ,computer ,washing machine,drills etc . the welder i use a big diesel kipor genny. 
at home extension lead from the inverter out through a window into the house .it then runs my house fridge . i turn off the trailer fridge . 
if its nice and sunny i also power the tall deepfreeze at home . sometimes the vacum ,computer , etc . 
by using the fridge as a guide, if the lights not working i check the inverter, if its screaming turn it off and use mains in the house . 
had to do that a few times this year already. 
normally it works from may till september no probs . i flatted the batteries the other day using the 1000watt karcher vacum in the trailer .cleaning it out ready for next winter . took too long . 
so far havent found anything it wont power . but i decided the micro wave uses too much power.
 its not recommended to power anything that forms heat . so it says in the instructions . 
yes i would recomend them to others . you can get a remote on off switch for them if its buried in a locker but i like mine where i can see it and keep a visual check on its lighting signals . 
if all the lights come up either the batteries are going down or i,m using too much power.
ring now market a slightly different version but talking with them awhile ago its very similar.


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## barmyfluid

Wow, well necromantic thread charming, but I've been doing a power audit for a boat and wincing at both power consumption of 12v fridges and prices for decent 'marine' versions.

As I understand it, a 240v domestic freezer or fridge doesn't throttle it's cooling, it's either on or off full bore between a set temperature range. Rather than all this talk of modifying a small chest freezer with thermostats/relays etc, wouldn't a low tech solution be to add some thermal ballast to the bottom (bricks, water bottles), which will also raise the level up to a more comfortable reach and just plug it in via a timer set to one hour every so often, and adjust it as required. It could probably stay off all night, as it's not being opened, and the ballast should even out temperature fluctuation in the day, not much different than using cold packs....

Any thoughts, drawbacks? I suppose if it was some kind of clever freezer that did something weird on mains power on it may not be happy cycling so much, but if it's just a cheap thermostat/relay/compressor job....?

Andy


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## barlicker

Get a AA or above rated domestic fridge and a decent inverter this will cost about the same or even less than an overrated Dometic fridge and you will get the use of the inverter for other gadgets.


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## barmyfluid

barlicker said:


> Get a AA or above rated domestic fridge and a decent inverter this will cost about the same or even less than an overrated Dometic fridge and you will get the use of the inverter for other gadgets.



It certainly would work better than getting one of the cheaper 12v fridges, which all seem to be about 45w and notionally take up 90Ah (I'd be interested to hear how much they actually use in the UK climate), as an A++ fridge by my reckoning at 93kWh takes up 22Ah (not accounting for inverter losses).

However, anecdotally a chest freezer can function as a fridge on just 3 hours out of 24 running, so while it may take more power in kWh terms (168kWh, the cheapest small one on AO) it's only running for an 8th of the day, so comes in about 5 Ah.

I'm actually designing a small LiFePO4 system matched with the most efficient engine charging, so while the Ah differences are not exactly huge, an extra 20 odd Ah will impact the price considerably in terms of batteries, alternators, DOD margins etc, not to mention fuel over time.

BTW, tired, not great with sums.

bx


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## exwindsurfer

oldtech said:


> Hi Ivecotrucker
> thanks for the reply .....* REALLY !
> *
> You may have saved me £700 !!!
> I saw a Waeco compressor fridge advertised on here ( 2nd hand ) a few months ago , then I got called away
> and forgot about it , and by the time I remembered a few weeks later and contacted the seller ..... it was sold.
> I was kind of cursing myself for a long time afterwards as I've read some good things about them.
> Makes me wonder now if the seller hadn't discovered the same issues as yourselves !!!
> It sounds like they may only really be suitable for hooked-up on-site use ..... and that doesn't interest
> me at all.
> 
> I'm determined to have a solar powered , nearly self-sufficient vehicle for long term wild-camping.
> I'm going to look for a small 2nd hand chest freezer and do some experiments  " in me shed " .
> You are dead right about manufactures claims for power consumption , probably the same as vehicle
> manufacturers claims for fuel ...ha ha.
> In the States there's something called a "Kill-a-watt meter" which you plug your appliance into , just like
> a time switch except that this logs the total power use over any period you choose... only $20 in the USA !!!
> I keep seeing stuff about them on solar power forums .....I'm going to try and get one ..........  today !!
> Anything positive to report and I'll put an update on this forum ....
> 
> In the meantime   "Happy Camping "
> 
> Oldtech
> 
> PS  just found a UK supplier !!   :dance:
> 
> £20 + p&p
> 
> Kill A Watt | REUK.co.uk



Hi oldtec I have ran a Waeco 110ltr compressure fridge for nearly five years now and have never had a prob with using to much power .Its the only fridge I would consider if I where buy new again .


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## Dowel

Have you seen these threads by wildebus? May be of interest.

https://www.wildcamping.co.uk/forum...idge-campervan.html?highlight=fridge+wildebus

https://www.wildcamping.co.uk/forum...nsumption-test.html?highlight=fridge+wildebus

I wonder whether insulation of fridges might be improved without altering the electrics and maybe providing the fridge radiator with a good direct supply of cool air from below the van may also increase efficiency?


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## runnach

Dowel said:


> Have you seen these threads by wildebus? May be of interest.
> 
> https://www.wildcamping.co.uk/forum...idge-campervan.html?highlight=fridge+wildebus
> 
> https://www.wildcamping.co.uk/forum...nsumption-test.html?highlight=fridge+wildebus
> 
> I wonder whether insulation of fridges might be improved without altering the electrics and maybe providing the fridge radiator with a good direct supply of cool air from below the van may also increase efficiency?


 It may well do , afterall refrigeration is about shifting heat form one place to another efficiently ,,One thing that hasn't been mentioned so far as I can  tell is fridges like air circulating inside to facilitate the cooling I saw lots of ridges in France customers complaining but the fridges packed to the rafters with food so air couldn't circulate. How we use fridges therefore can make a difference to performance 

Channa


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## colinm

Dowel said:


> I wonder whether insulation of fridges might be improved without altering the electrics and maybe providing the fridge radiator with a good direct supply of cool air from below the van may also increase efficiency?



Going back to OP, there are a couple of things which make this no longer relevant and not so good for a van, back when the linked article was published it was comparing a inefficient US fridge with a freezer, since then and in europe the insulation of fridges (in some cases) has improved a great deal, so the operating power usage with door closed is pretty much the same, this leaves the only way it is more efficient being a top opening door, for a house with plenty of room this is ok, but in a limited space van this eats into space one way or other, either you have to leave space above door to allow it to open,or you use door as worktop and then have to clear it to open door.
There is another option I suppose you could put fridge on casters and wheel it in and out of a space, but it doesn't make it easy to use.
btw, we had a large top opening thermo electric fridge in old van, it was quite efficient, but we find the present front opening door much better in use.


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## Fletch6

.


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## maxi77

Better insulation will improve the performance of any fridge or freezer. Many liveaboard yachties build their own fridges with very serious insulation to reduce the power input. Reducing the duuty cycle down to 20% or less is possible compared to the 33% for ready made Dometic units. They all use compressor kits which are supplied by the likes of Dometic with 12 volt compressors. Not cheap but efficient and outperform any off the shelf unit. Whilst this is really not an option for factory built vans for self build it must be a real option. In hot climates absorption fridges need good ventilation but are hamstrung by the reality they can only cool to 30 degrees below ambient.

Edited to add some idea of the kits available. Most of the parts have self sealing connectors which means no nasty problems with refrigerant gas a much easier DIY solution

Refrigeration Units


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## photize

Continued quest:

I was researching the same problem here are 2 great videos which may help the decision and save money etc.
the presenter is obviously attempting to promote an inventor but I do not think it interferes with the results.
Enjoy
Pho

Fridge Comparison Energy Consumption test with multiple fridge types in the leisure industry
230V Fridge comparison test versus a 12V compressor fridge cost / benefit analysis


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## runnach

hairydog said:


> I've read that in several places, but it is utterly untrue. My gas fridge was in temperatures of 37 degrees last year, but the freezer was at -19. That is a 56 degree difference. It could manage  better, if needed. It's down to how well it is installed.



Ambients do play an important part with absorption fridges purely on the principal of how they work...But I agree with you the quality of installation is key. It figures adjacent to ovens direct sunlight they aren't going to do as well as other locations.

Irrefutable evidence again by how they work compressor units are more effective. that is no slur on absorption cycle fridges and in the main serve well 

Channa


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## Nabsim

Compressor fridge works great for us, never seems to pull much power although only been in the uk this year with it, saying that we have had some 30 degree days although not many.

I think a lot will depend on what you have unless starting out from scratch as the costs of either are high. Ignore the horror stories you read about compressor fridges though they aren’t true.


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## ScoTTyBEEE

hairydog said:


> Yes, a compressor fridge is far more efficient. But the power supply is far less efficient. 1KG of propane has 13KWh of power (plus the weight of the tank, of course). A battery with that much power storage capacity would weigh around 300KG.
> The problem for absorption fridges is that the hotter the weather, the more work they have to do, which produces even more heat.
> Unless the installation has been designed to dissipate that much heat, you can get into a form of thermal runaway, where it gets hotter and hotter behind the back of the fridge, making an impossible thermal hill to climb.
> Big, how the vents, good ducting and maybe fans all make it work, but motorhome makers like to cut corners and fit "good enough" setups.



I installed a couple of 12v computer fans on the upper fridge vent and it's made a huge difference, currently S.France and fridge maintains 4-5c all day. They're also essential because if I keep my sliding door open this covers the fridge vents and pretty much stops it working.


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## wildebus

Said by HD .... "Yes, a compressor fridge is far more efficient. But the power supply is far less efficient. 1KG of propane has 13KWh of power (plus the weight of the tank, of course). A battery with that much power storage capacity would weigh around 300KG."

But if "a compressor fridge is far more efficient" you wouldn't need "that much power storage capacity" would you?


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## Derekoak

*Best fridge*

I just read this long thread. Ignoring the tech which we may not understand, there are some quietly saying my compressor fridge works fine and others saying my 3 way fridge works but..... That is also my experience.
Solar panels allow you to suck energy out of the environment most of the year, at a rate plenty high enough to run an efficient fridge, so i run my fridge with only one 85 amp hour battery. The comparative weight of gas to batteries is not relevant. I bet hairy dog has more batteries than me?


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## Glass man

My Dometic 3 way is sensitive to the mains voltage,  it won't work below 200V


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## runnach

wildebus said:


> Said by HD .... "Yes, a compressor fridge is far more efficient. But the power supply is far less efficient. 1KG of propane has 13KWh of power (plus the weight of the tank, of course). A battery with that much power storage capacity would weigh around 300KG."
> 
> But if "a compressor fridge is far more efficient" you wouldn't need "that much power storage capacity" would you?



13 -14  kw of gas produced per kilo ....only tells part of the story . whilst correct ......it should be remembered on smaller bottles eg a 6kg propane the maximum take off the regulator can cope with is  .79 kg per hour  a 47 kg closer to 2.5 kg/hour. 

It is like having a Mc Laren capable of close to 200 mph but slapping a governor on it restricting to 56 mph. 

Channa


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## wildebus

channa said:


> 13 -14  kw of gas produced per kilo ....only tells part of the story . whilst correct ......it should be remembered on smaller bottles eg a 6kg propane the maximum take off the regulator can cope with is  .79 kg per hour  a 47 kg closer to 2.5 kg/hour.
> 
> It is like having a Mc Laren capable of close to 200 mph but slapping a governor on it restricting to 56 mph.
> 
> Channa



Don't know.  Don't care.  Gasless     (in case this was a reply specifically to me  )


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## runnach

wildebus said:


> Don't know.  Don't care.  Gasless     (in case this was a reply specifically to me  )


 Gasless indeed. However lots reading the thread, so might be useful to someone....We read constantly this works and that doesn't on gas and a lot of the time for reasons I have explained is probably the reason on vans with smaller gas bottles often overlooked IMHO

An interesting fred !!:dog:

Channa


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## wildebus

Just some musings on "most efficient fridge on the planet" question ...

What does efficient mean?  most efficient in terms of energy? space? weight? cost?

Take the example of Colin Campervan, who has got a basic setup a lot like many people.  E.G.  A gas stove to cook on (so he has LPG on board and plumbed in);  a Leisure Battery to run his lights, TV, what-have-you;  and he has a Solar Panel as he likes to go wild camping.
Pretty standard stuff nowadays?  Of course not everyone has solar, and not everyone has gas (I don't) - but most nowadays do I think we could hopefully agree on?

Now what Colin Campervan is wondering is does he go 3-Way Absorption Fridge, or Compressor Fridge in his brand new campervan?

What is the TCO (Total Cost of Ownership) of each?
Need to consider:

Initial Cost of Purchase and Installation
Annual Maintenance Costs
Annual Running Costs
Lifetime of Fridge

*Initial Cost of Purchase and Installation*
Purchase:  
You can support a Compressor Fridge running with a basic 100Ah Battery and 100W Solar Panel for the significant majority of the year when you also consider the batteries will get charged from the alternator as well on a fairly frequent basis. To add a100Ah Battery and 100W Solar to an existing install will cost around £250 with all parts needed
The Absorption Fridge just needs more gas, so no extra energy storage infrastructure to add in there.
Fridge Prices are whatever they are, but I think 3-Way Absorption Fridges and 12V Compressor Fridges are fairly comparable in price.

Installation: 
A 12V Compressor Fridge is very easy to install, so a DIY job or cheap from a Fitter.  The Battery Install and Solar Addition may need to be farmed out depending on circumstances.
An 3-Way Fridge is much more complex and likely a third-party install.
Let's assume the 3-Way Fridge install will cost the same as getting the 12V Compressor Fridge plus Battery and Solar Upgrade installed.

So - Right now, I am seeing the cost of a 3-Way Fridge Installation and energy store made available (pipe from tank plumbed to fridge) to be the same as a 12V Compressor  Fridge and energy store made available (Battery and Solar upgrade installed)

So currently, assuming Fridges costs same to buy and the same to install (as described above), *a Compresser Fridge has an initial extra outlay of £250*



*Annual Maintenance Costs*
A Compressor Fridge requires no maintenance.  If we assume the Leisure Battery will last up to the warranty period of say 5 years, then spread the replacement cost (£125) per year and the Compressor Fridge costs £25 a year to 'service'.  Solar Panels last 20+ years and will likely outlive the van and maybe the owner!  so ignore the replacment costs
A 3-Way Fridge should be serviced every year.  Maybe £75 a year? (just guessing at a hours rate from a commercial motorhome dealer with parts)

So if you work on a 5-year basis, the 12V Compressor Fridge will have cost you £125 in Maintenance  (a new battery); while a 3-Way Fridge will have cost you £375 in servicing, so *the 3-Way compressor fridge will have incurred an extra service outlay of £250*



*Annual Running Costs*
12V Compressor Fridge will cost nothing to run.
A 3-way Absorption Fridge will cost you the gas - around 0.2L a day? so around £1 a week?


*Lifetime of Fridge*
Probably the same, so going to make this a draw.


Conclusion - if my numbers are right ....
The only difference cost wise over a 5 year period between the two is the running costs, and the Compressor Fridge wins by around £1 a week, so not a major difference in truth.
Obviously lots of assumptions and this is very much rule of thumb.


Other Factors:
weight: - extra battery and solar panel - maybe 30Kg
space: - equal to a battery
'Green' Factor: - solar recharging much more eco than fossil fuel burning
Install: - ugly vents in side of vehicle for gas Fridge
Usability: - Compressor Fridge just works;  3-Way needs switching over to different supplies = more hassles




FWIW, my OWN solution:  Compressor Fridge, but actually a 230V AC one with an Inverter.  As energy efficient as a 12V Compressor Fridge even with Inverter included.
Cost of 230V A++ rated Compressor Fridge + Inverter  + 110Ah battery + 100W Solar Panel = £500, so LESS than either a 12V Compressor Fridge on its own or a 3-Way Absorption Fridge BEFORE their installation and extra costs described above are considered, and zero running costs  (been on since last October near enough non-stop)


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## runnach

By your own admission or careful posting assumptions which make an Ass out of U and ME ..actual comparisons apple for apples is difficult to achieve 

I had an absorption fridge and never an ounce of bother and did what was reasonably expected of it so your maintenance assumptions way off the mark ( in my experience not theory but experience)

Of course others may share a different experience 

You have via experience given an account of running a fridge on electric only via a victron inverter and some interesting results

Personally there is nothing to convince me I should go electric after the cost of inverters et al others may feel different.

That is not to say I don't enjoy reading your tests, 

There is another thread running at present re fridges someone trying to re invent the wheel re three ways ...in my opinion not that my opinion matters. 

Channa


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## mistericeman

There is no way of comparing like for like as there are so many variables....

Existing vehicle with a 3 way.... 
Makes little sense IMHO to change it for a compressor type (unless you already have solar/batteries)or need the better/more reliable performance of a compressor type 

New build with gas on board and not bothered about cutting holes for vents/flue etc and little solar/Battery 
Again 3 way is possibly better choice. 

New build with solar/batteries and dont want vents cutting...
Compressor fridge makes more sense.


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## wildebus

Ahh ... but you are gas-savvy and know and understand 3-Way Fridges.  
(my assumptions included the assumption that no repairs were needed to anything, including the gas fridge). However the *official recommendation* from the manufactuers with a 3-Way fridge is an annual inspection.  If that was done as per recommendations, how much would it cost? How much would YOU charge - not as a favour, but as a business and including VAT and other overheads you have to cover? is £75 really "way off the mark"?

My conclusions - with loads of assumptions in there, but not too silly and not weighted in one direction or the other, would say to me that if I had a working fridge - of EITHER flavour - I certainly would not SAVE money by removing it and buying another of a different type.  BUT .... if the Fridge broke, THEN I would consider what is best - a straight replacement or a change of direction.

And the other aspect is the user - if Full-Timing, then an electric-only fridge could be a problem in the winter possibly depending on how/where the user stays.  and the variables go on ...


If I were building a Camper for someone and they asked me what kind of fridge to go for, I would run through the variables with them and tell THEM to decide, but chances are would recommend a 12V Compressor Fridge in nearly all cases as that is the easiest option for an individual to operate, the cheapest option between the two for a holiday camper to install and the cheapest option to run.


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## mark61

Talking of efficiency, in my current van I had a Webasto front loader compressor fridge fitted (CR49 i think ) It worked ok but was never 100% happy with it, always seemed to be working harder than my old Engels fridge, but worse on a few occasions on rough tracks the door would open due to vibrations. I know I could easily have fitted an additional clip, but decided to take it out and put the Engels in. I suspect the Engels is better quality, but the big difference it’s a top loader. I haven’t recorded any figures re the two fridges to back this up,  but my gut feeling is that the Engels uses a lot less power, and on stationary days when fridge is opened a lot more, I wouldn’t be surprised if it uses less than half the power of the front loader.


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## Derekoak

*Lpg v solar*

Ok I will take your figures and convert to my system. We have a 70 litre vitrifrigo fridge i think it runs on about an amp hour per hour. We switch off at night because my wife does not like the fan noise so 16 amp hour per day even if running all the rest of the time. We have solar 160 watt but say we are in scotland in winter? Even there it gives something, and we probably do not need a fridge . Everywhere else we have no problem at all . We still drive every day as we wild camp. We have a 30 amp ring b2b so we get our 16 amp hour in  less than 1 hour of driving. Our last camper with a similar system was still going strong on its first leisure battery after 5 years. We need our leisure battery anyway for led lights and recharging and propex fan and a small inverter. So worst case is your 12.5% of our 110 amp battery. 0.1% of 100 pounds. 10 p double what you say your power costs are from lpg, but mine is  an unfair worst case, scottish winter with the fridge running full bore 16 hours a day.  I have an lpg tank too by the way for cooking and heating, but 1140 watt hour of power now has to be used in an inefficient absorbtion fridge. I do not know but probably 2 to 3 times less efficient than a compressor. So on those cost I am ahead I think.  I assume any alternator recharge does take some diesel to run the b2b but in Scotland in winter the fridge probably did not come on much.
 your system burns fossil fuels to produce masses of uncomfortable heat especially when it is hot outside. Many people have trouble with absorbtion fridges and level and not working in heat. If it is really hot my thermostat is in the middle normally I have plenty of capacity. For me in a micro camper absobtion fridges take up more room with all their flues.


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## exwindsurfer

I’ve ran my Waeco 110ltr fridge now for five years and never found it used all my battery power I started off with two 125amp batteries and one 140 watt solar and it was never a prob .Now I have three batteries and 400watts of solar even in the winter I never had prods with the smaller solar so I am well pleased with my set up .I only opt for more solar because I could not because I need to .


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## wildebus

mark61 said:


> Talking of efficiency, in my current van I had a Webasto front loader compressor fridge fitted (CR49 i think ) It worked ok but was never 100% happy with it, always seemed to be working harder than my old Engels fridge, but worse on a few occasions on rough tracks the door would open due to vibrations. I know I could easily have fitted an additional clip, but decided to take it out and put the Engels in. I suspect the Engels is better quality, but the big difference it’s a top loader. I haven’t recorded any figures re the two fridges to back this up,  but my gut feeling is that the Engels uses a lot less power, and on stationary days when fridge is opened a lot more, I wouldn’t be surprised if it uses less than half the power of the front loader.



A good point - and this comes down to personal efficiency as well (so still all depends of what kind of efficiency one is looking for)
I had a Waeco Coolfreeze CDF-36 on a slide-out system on my VW T4 Campervan. Ran that with a single 100Ah Battery and 160W of Solar on the Roof and it was great and never left me short of power.
Excellent Compressor Coolbox and super-efficient. But ... having to rummage though it to find what you wanted could be a PITA. When I did my next camper (VW T5) I decided to sell the CDF-36 rather than transfer it, and switched to a Waeco CRX-50 even though it was a little less efficient as I wanted to be able to just open the door and pick up something from a shelf or from the door pockets. 
Better _Personal _Efficiency won over Better _Energy _Efficiency in my case


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## Nabsim

If we really wanted super efficiency would we be driving round in vans/mh's anyway?

When I go to add something or if something breaks I want to fit whatever will work best for me but apart from that I will run whatever is fitted and working. I hardly use any gas so use more electric, if anything we should be looking at fitting domestic fridges like Dave has done when they expire then we can saw several hundred pounds on the appliance


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## Nabsim

hairydog said:


> There seems to be a cognitive dissonance here. If 12v fridges use so little power, why are people adding solar panels and bigger and bigger battery banks?



I want a bit moe as I am going to fit a 12v emersion


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## wildebus

*Quote Originally Posted by hairydog View Post
There seems to be a cognitive dissonance here. If 12v fridges use so little power, why are people adding solar panels and bigger and bigger battery banks?*



Nabsim said:


> I want a bit moe as I am going to fit a 12v emersion



There seems to an assumption that fitting +12V fridges and adding more solar and battery have a direct correlation?
In my own case (can't talk about others), I have a big battery bank and big solar array as I want to be able to have my vehicle off-grid and continue to use power tools - 1600W heat gun, 700W jigsaw, 1300W Router etc. 
And when it is not providing power for that (which of course is the great majority of the time) the spare power is available for a 2000W induction hob, 180W Slow Cooker, 750W George Foreman Grill, etc.



Oh, and the Compressor Fridge with its average 14W power draw can sit in the background using a couple of % of the battery bank resource keeping my food chilled 

(2.5% used, which includes Roof Fan being on sometimes (auto-starts on temp setting) plus internet router and signal booster and Raspberry Pi Computer)



SOC-Overnight by David, on Flickr
I don't think I would have added extra capacity just to make sure I only used 2.5% overnight?


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## mistericeman

wildebus said:


> *Quote Originally Posted by hairydog View Post
> There seems to be a cognitive dissonance here. If 12v fridges use so little power, why are people adding solar panels and bigger and bigger battery banks?*
> 
> 
> 
> There seems to an assumption that fitting +12V fridges and adding more solar and battery have a direct correlation?
> In my own case (can't talk about others), I have a big battery bank and big solar array as I want to be able to have my vehicle off-grid and continue to use power tools - 1600W heat gun, 700W jigsaw, 1300W Router etc.
> And when it is not providing power for that (which of course is the great majority of the time) the spare power is available for a 2000W induction hob, 180W Slow Cooker, 750W George Foreman Grill, etc.
> 
> 
> 
> Oh, and the Compressor Fridge with its average 14W power draw can sit in the background using a couple of % of the battery bank resource keeping my food chilled
> 
> (2.5% used, which includes Roof Fan being on sometimes (auto-starts on temp setting) plus internet router and signal booster and Raspberry Pi Computer)
> 
> 
> 
> SOC-Overnight by David, on Flickr
> I don't think I would have added extra capacity just to make sure I only used 2.5% overnight?



Same here.... 
We went for solar/batteries to power inverter for microwave/toaster /kettle /slow cooker etc.... 
Having spare for Waeco compressor coolbox was a bonus.


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## Derekoak

*Gas v solar*



hairydog said:


> 10p worth of gas is around 1300 watt hours of power. 12.5% of a 100Ah battery is around 140 watt hours of power. So the compressor would need to be nine times as efficient, not three times.
> I take your point about badly installed gas fridges. There are lots of them around!


Ok i was reusing your figures. 3 times out is not very much. I was comparing solar in scottish winter,  and a fridge running 16 amp hour per day when it might not switch on at all, i could re estimate too.  What about all the waste heat you have to get rid of in the hot south of france and the side of your van that is a no go area.


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## wildebus

The heat aspect could be wanted in winter but for most people it is not. And THAT is another benefit for using an induction hob instead of a gas hob for cooking (expanding the efficiency discussion). 
I can boil water on my hob at just about the same speed as in the kettle at home. On a Gas hob it takes a fair bit longer and heats up the interior quicker than the water!


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## Derekoak

*Clarify?*



hairydog said:


> I very much doubt that my figures were out by a factor of three. If they were, I need to correct them. Can you clarify how you were reusing my figures?



I explained what i did with your figures as best i can in post 53. A factor of 3 is not a small error although we are both using approximations. But really the choice comes down to other factors than only efficiency.


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