Most efficient fridge on the planet !!

[Channa]

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

 

[wildebus]

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 )

 

[Channa]

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

 

[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)

 

[Channa]

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

 

[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.

 

[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.

 

[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.

 

[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.

 

[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 .

 

[wildebus]

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

 

[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

 

[Nabsim]

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

 

[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?

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?

 

[mistericeman]

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.

 

[Derekoak]

Gas v solar

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.

 

[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!

 

[Derekoak]

Clarify?

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.