Second Fridge - 50L or 80L?

Appreciate the reply mate
I think you've hit the nail on the head for me

A 60L is much more user friendly, both in form factor and power usage
I also had not considered the cooling efficiency you've mentioned

SD, take a couple of empty 4lt wine bladders, or a 10lt water cask bladder, and inflate these to take up excess voids in the fridge as room comes available.
That dead space is very inefficient and makes the fridge or freezer cycle on a lot more.

Wondering what difference that would make?? Air in the cask bladder to air in the cabinet of the fridge?

Stops air movement, like when near an undrapped window inside a home you can feel a draft next to the glass, or big empty space air mattresses are really cold as they have no internal closed cell to limit air moving.

Think you may have been sampling the contents ????????????
Cheers

Ha, ha :D
I use the water bladders myself, wine should be had from bottles if one indulges :)
It really is right though about the space and air movement, trust me I know this from numerous experiences.

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Actually Les, for efficient fridge operation, air movement is exactly what is desired. That is why most modern kitchen fridges have fans within them.
Moving the air around ensures a more even temperature within the chamber and eliminates gradients.

The fuller a fridge or ice box is, the less it takes to keep cool.
If you turn your fridge on empty and get down to temp for a coupe of hours, just monitor how often it cycles then (mind on, mins off, mins on, etc for say a dozen cycles, then do it next time it's loaded for a trip.

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That seems to be a popular belief Les, but it simply ain't true. An Old Chestnut I'm afraid.

Certainly the cycle on/off time will vary between an empty and a full fridge because of the thermal inertial mass of the contents but the total run time remains the same. It's not a matter of how often it cycles, it is how long it runs.
Once the contents are down to the set temperature, the only need for energy input to a fridge is to replace the losses due to heat ingress through the insulation and through opening the lid. These losses remain the same, full or empty.
This is fundamental thermodynamics........very basic physics.

How often it cycles and runs between cycling are related I found when testing this.
I'll keep using the bladder when the fridge gets down about 3/4 and lower, as it runs up around 15% less from my initial testing.
I used both timing of cycling on / off, and on the 240 adaptor had one of the little power use meters on the power point.
Was quite noticeable having it empty or at least half full of drinks.

Timing is a pita though, as sometimes it takes like 20 mins in the cycle off stage, if you leave the room to do whatever, sure enough it comes on while you're gone, so might be out a minute here and there.
The meter usage showed lower power use, when less space, so I figured it therefore must be running and cycling less.

I did this over a couple of days at various times empty, then with a heap of drinks in there.
Anyway, power use isn't vital in most cases, suppose if a battery is dodgy when out bush you can just turn the fridge off at night and run it during the day.
They cycle bugger all through the cooler nights, and temps stay up well through to sun up.
I had this happen in the Simpson one trip when my arkpak charger failed (pre charging by alternator setup) and it would be 5 to 8c or so still of a morning.

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Well Les, I'm afraid we will have to continue to disagree between the scientific and the anecdotal.

As for the "cooler nights maintaining temps"....... as the overnight air temperature in the Simpson is usually in the order of "5 to 8c" (or less) then it is not surprising that a fridge has no trouble in maintaining a similar temperature. lol

Where is Julius Sumner-Miller when he is needed?

I guess so Allan, though having tested it over 2 weeks I know there was taht ~ 15% difference.
So my info isn't anecdotal, probably not 100% controlled by scientific methods, but the difference was noticeable enough to get me taking time to do the bladder thing, and it isn't much of an impost.

Be interesting to try it for yourself with the power point meter, they're only $10 pr so sometimes at the electronic places.

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I already possess instruments to accurately measure electrical power Les so maybe I will find time to carry out a test. But what then if it disagrees with your results?

Incidentally, with your test running for 2 weeks, was the ambient maintained at a constant throughout? I don't have access to a temperature controlled room. lol

Guys
You are both correct - in part.
The benefit of a full fridge is, that when you open it, the "contents" being hard stuff, doesn't escape.
When you open an empty fridge, the cold "contents" being air, escapes and the fridge need to cool down new "content" being warm air.
That's my theory anyway, but what is fact for me through experience, is that a full fridge takes less power to keep cool, and I guess it is because of more cold escaping every time you open it (and we do that a lot being 5 of us)

Allan, my testing was done in the home kitchen, temp pretty stable, not enough variance to affect the various readings.

Cheers, let us know if you ever do this, would be interesting to see your results.
I would have long ago tossed my original Technii testing notes.

I have found that over the past 12yrs with my Evakool RF47 runs more when it is full but it also has the cooling element at one end so each type of fridge will give different results. The contents are not individually insulated so they don't store cold very well so the cold can escape from items when it cycles even though their inside the fridge if you know what I mean. Placing items in there to take up space like empty milk cartons when it is slowly getting emptied makes the items at the warmer end of the fridge even warmer because I'm now blocking the cold air from getting to them with an item that is not solid it is filled with air and is less efficient at passing cold air through compared to a solid item which can store and release cold when the fridge cycles.

It cycles less when is has less contents in it and I don't fill the gaps with anything because the open space helps to spread the cooler air throughout the fridge so the warmer end drops about 2 deg which helps it to cycle less.

My neighbours Techniice fridge has the cooling element on all 4 sides like my Waeco CDF11 console fridge so it has a more even and constant temp spread throughout the fridge so the items are cool all round so it cycles less. I don't know if filling the empty space with hollow air filled items would help or not but I would also expect if doing that it would limit the cold air from getting to the items in the centre of the fridge from above so it may not help there's a bit to it when you look into it.

Also as people probably know that apparently if you fit a small computer fan inside your car fridge so it turns on when the fridge cycles it will help keep the items throughout the fridge cooler and overall use less power because the fridge will cycle less. I was going to try this a while ago with my old Evakool but haven't had time yet. Has anybody else had success with this idea which sounds feasible.

That fridge design could be the reason Batts, thanks.
I have both the Techii and Waeco cdf11, though haven't bothered tested the Waeco.
They do have plates all around.
Note, with the Technii, I used to keep early frozen stuff around the plates (basket left out) and beer in the middle, it worked quite well and fits with what you said a couple of posts up.

Les have you been on the Techniice web site lately they don't sell fridges any more by the looks of it I wonder why they seemed ok.

Batts, hadn't been there for maybe a few weeks, but yeah, only ice boxes now.
They did change their fridge range quite considerably in recent maybe 6 months.
Went from my kind of Technii which is plastic moulded (looks very similar to many on the market, generic factory thing) to a metal construction.
Their prices went from (my 45lt) $550 odd inc cover and power cords etc, to up near $900.
Shame, they are good, seemed to be leaders in low power consumption, and my fridge works great at all temps, just had faulty cable early on, which a new Waeco cord fixed.

Sounds like the same fridge my neighbour has it came with a cover it hasn't missed a beat yet and yes very good on power. I may have mentioned once before on a 120ah battery set at 2 deg after 4 days the battery has dropped to 70% that's during summer which is pretty good.

70% left or 70% gone?

To help clear things up the battery started at 100% fully charged then " it dropped to 70% " according to the meter on his Arkpak which means it didn't drop down by 70% that could cause harm to the battery. I can see where the mix up may happen I said to 70% where if I said 70% left that may be easier to understand to easy chow.

That is impressive, then again, those ArkPak displays read very much incorrectly and always in your favour, not the Batteries.
The ONLY way you can check what state the ArkPak is at, is to plug the mains back into it, then see what it reads, as it will always drop lower than what it says in the Vehicle.

I have the ArkPak with a 100Ah, i can get 3 days in 38 degree heat (20 degree nights) and have the Battery at 50% SoC on the ArkPak display, when i get it home and plug it in and the Charging begins, the Battery will actually be at 30% remaining :(

Fridge is a Weaco CF40 with a Bag enclosed in a Van.

I'll also not, the first 2 days, the ArkPak will DIsplay 97% or 95% or Perhaps 90%, then at the end of the 3rd day, it take a huge dive to 70% or 65%.
I find it a handy reference, but it is hard trust and certainly is hard give accurate Battery usage figures from.

I measure the ArkPak both with the Compressor running and without, to try and obtain the most accurate guess i can manage.

I can even have the ArkPak connected to my Vehicle Alternator for the drive home (4hours) and the DIsplay will read 100% after driving for the first hour, yet once home and pop it back on the workbench and plug the 250V adapter in, the State of Charge will be anywhere from 45% to 60%.

So probably hard to work out what a certain fridge draws.
All i have now is my law of averages from multiple trips.

I don't think my neighbour has had an real issues with it reading incorrectly. Have you checked it with a multimeter to see if it's accurate. Also as you probably know usually it will fluctuate when the fridge is cycling so best to check when it's not running. Also when drawing power off it or charging the battery you need to let it sit for a while to get a true reading especially after charging I read somewhere that you should wait at least 2 hours for it to settle.

Ambient temp plays a big roll in it as well I have 2 x 105 ah agm's in parallel they usually read around 12.9 to 13.1v on warmer days but in the cooler weather recently I have seen them around 13.2 to 13.3v after the vehicle has been sitting overnight so that may get me an extra day or more running the fridge in ideal conditions. But I fitted a 170w solar panel to my roof recently so hopefully they are kept topped up but that's getting away from the subject.

I have checked my Arkpak (100 amp/hr AGM battery) many times, just turned on, and whether powering anything or not, it is always within 0.1v of what a multimeter reading is.

The Arkpak readings are all accurate too when charging, either from the alternator or a battery charger, usually about the 14.7v mark.

But if I had the old 12v Arkpak charger on it (this was pre alternator system hook up, and before two 12v chargers failed in 3 months) and say the solar panel, it would screw up big time and often come up with an error.
Didn't like multiple charging sources, might have been too many amps or something, the charger was 6 amps, the solar 6 amps.

The largest mains battery charger I have is 6amp which conditions it nicely every couple of months.

Its not an issue with your Neighbour reading it correctly or Incorrectly
It is the nature of the product.
I was involved with ArkPak when it was first released.
It was explained to everyone that it is just a guide and not an accurate reading.

However, i do agree with your neighbours reading considering he has a 120ah Battery installed, that does sound about right... and if anything, a bit too good, but believable.

Testing with a Multi Meter will get you the exact same reading every time.
Yes, that is once the surface Voltage has been removed.
What ever the ArkPAk displays the Multi meter will display.
Same for any Battery.

It is the discrepancy between testing the Battery with a Multimeter or When in a Charging phase.

I believe an efficient fridge, with good insulation can return those figures over 4 days.

874855

Les, i have 3 ArkPaks, all 3 with 100Ah AGMs in them.
All 3 stay on the supplied 240v Adaptor 24/7 365.

Yes, you can sometimes get an Error when they are fully charged and the Charging cycle is started again by the power going on and off etc.
It is just a protection circuit, which Open Circuits the charging.....
If left to sit, it sorts itself out and resumes without a problem.
Or you can plug a load in, like a fridge for a few minutes and it will correct itself.

Yes, the first model had some strange traits.

Batt's, ask your neighbour what the ArkPak displayed once he got home after 4 days and plugged in the 240v adaptor, that is the reading we are talking about.
That would seem to the more accurate one.

Don't think he would remember he done this awhile ago at home. I was just originally mentioning to Les about how good they are on power in hot weather.

Yes, i have had my eye on the South African Luna's for 6 or 7 years now.
Nice looking units.
How have you found the power usage?
People have told me they draw a lot, yet you seem very happy.
Considering you've had the Engels, can you make a comparison?

I bought the 20l to use as a freezer but found that up north in the heat it would run continuously and still not be cold enough. Fine as a fridge or freezer in the cooler country but not when it got above mid 30's. they just haven't got enough cooling pipes to be a freezer in the heat. Also , although Engels are a great fridge their insulation does let them down..the 40l worked well in any temp..even with both on fridge there was always 1 or both running in the hot weather.
We did a trip earlier this year to the ropper river,Karumba etc and it was pretty hot. I had the small part of the national luna on -15 and th bigger part just cold enough not to freeze the beer. Really happy with the way it performed. The insulation is very good and the compressor runs no where near as much as 2 Engels.
Good luck
Danny

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Hi Les,

I agree with you about loading just enough drinks for the next 24hrs.

I also added a Waeco CDF-11 in a console location to run as a freezer leaving the 35L as a +4 degree fridge. That has worked fine and I was surprised at just how much meat etc. we could load into the 11L freezer. A bonus was that I modified the CDF-11 to accommodate our water bottles through the lid to have chilled water on hand. Being in the very upper part of the fridge they do not freeze.

The "Evakool with a drawer" is innovative, but my experience with all fridges is that they are colder in the bottom zone than in the upper. So I would have thought that this fridge would operate better if run so that the bottom zone was run as a freezer leaving the upper zone for food and drinks.

Cheers Allan, your little Waeco 11 mods with the water bottle access is pretty neat.
I feel with generally named fridge / freezers, they are really used as either a fridge or freezer, unless they are a true 2 space / 2 lid type with dual controls.

Like this 70lt size or 60lt size.

Maybe this is a better option for the OP, as I imagine they use less power, and you could possibly leave the normal freezer part set at highest setting (or deactivate ?) if you were only doing a small / mid size trip and only needed a fridge for those ventures.

I do run my Tecnii as a fridge at 0c on trips, this cycles from -2 to 2, and seems ideal for our needs.
When using it for some items taken from home deep frozen, we'd place these packs of steak, chicken etc around the side plates, and drinks / other non frozen food in the middle.
This kept frozen packs in that state for up to 4 to 5 days or so, extending that frozen food somewhat to last a couple of weeks.

Mind you, if you cryo / vacuum seal your meats, even chicken, and just use your fridge, it will last many weeks, if not months.
I do a bit of this already, but haven't fully trusted chicken (for example) more than a couple of weeks anyway.

So much fun doing meals planning for trips, such a pity I haven't really got anything big planned until June next year :(

Hi Les, well there is just me, or Me and Mrs.
But i am thinking of Simpson Trip with the boys and No girls.
2 Vehicles, i have a Waeco 40L, Friend has a Waeco 50L and another friend has an Engal 50L.

So we no doubt have enough for our trip.

When it is just me and Mrs, the 40L is fine, as you all say, we pack it at night or in the morning with what we need in regards to drinks for the day.
Then i sometimes do the "Remove 1, Replace 1" theory if i can be bothered.

The system works ok, but this is for travels that are not too far from towns and shops.
So re filling with food is easy on the fly.

Wow, thanks for the link of the Combo Draw fridge
That is an awesome design, just a shame its one of Supercheaps elcheapo products :(
Still, that solves a lot of issues with 4WDs and draw systems with a fridge on top.

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Les, an issue with fridge temperature is the location of the measurement sensor, so comparisons may not be valid. With at least some Waeco's it is located under the floor of the cabinet and this also is used to display the temperature. I don't know about others. I added an independent digital temperature display to mine with the sensor internal and halfway up the side. This is what I use to set at 4 degrees as mine has no original indicator.

We also cryovac from departure and try to buy cryovaced meat en-route. Like you, we treat any chicken as two weeks only.

The Supercheap fridge is the evakool rebranded, so should be fine ?

My Technii 45lt is going on 4 years now, lowest power use I have seen, and only a dud plug at early stage let me down, replaced under warranty.
Loads of desert / corro road trip under the belt.

I would personally just run with what you have, should be workable, and if you don't have a cryo / vacuum sealer, maybe just splash out on one of those ?
You can take each nights meat from around the side where the plate is each morning, and place in the small section up top if needed, it'll be defrosted fine for the nights meal.
Amazing how much you can fit in with flat packs of cryo food.

Cheers Allan, for sure every fridge has its little idiosyncrasies, between brand models/ sizes even, but obviously different brands especially can require tweaking of temps to suit individual needs and trips.
I find the Waeco 11lt uses more than the Technii 45lt, even during testing as a fridge.

Thanks Allan.

1. Yes, i struggle with my 40L filled, i'm not even going to consider lifting an 80L filled :)

2. Yes, Power Consumption is always an issue, i have 2 x 100Ah Batts + Engine Batt, but still i will need a Solar Panel if stopping more than 2 days.

3. Yes, i can see the advantages of 2 similar sized Fridge/Freezers.
I can then run them in what ever combo i need.
Plus the obvious weight/handling benefits.

Thanks fellas... i think that makes it a clear choice for me now