17' Series Travelling with fridge on 12v

Sep 4, 2017
14
7
3
48
Malmsbury
#1
Hi, I'm new to caravanning and purchased a 2012 17.56 expanda recently and I have worked out how to operate most things but I have a question about the fridge operation when travelling. It has a large domestic 3 way fridge. People have told me I should run the fridge for 1-2 days on mains power before leaving and then switch it over to 12v while travelling,is this correct? Or should I get an Anderson plug connection which I assume goes directly from the car battery to the fridge bypassing the caravan battery? Thanks in advance for the help great site. Chris
 

relgate

Superstar
Staff member
Feb 2, 2012
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Sydney, NSW
#2
Correct Chris. You need to charge directly from the vehicle battery. Does the van have an anderson plug? From factory it probably came with a flat 12 pin and the fridge would be wired into it. I dont know off hand the pin no.
People often rewire with bigger gauge wire to Anderson plug.

Also. Note that you will quickly flatten your vehicle battery when ignitiin is off so add solenoid/relay or fridge switch to cut power when stopping for lunch etc
 
Sep 4, 2017
14
7
3
48
Malmsbury
#3
Thanks for that relgate. It does not have a Anderson plug for fridge. I was told you could get a fridge switch when stopping for lunch etc. is it worth setting up the Anderson plug for the fridge or shall I just see how it goes on our first trip? Thanks in advance.
 

twscoot

Well-Known Member
Jun 9, 2013
975
1,668
93
Brisbane
#4
@relgate is on the money. And your advice about running the fridge for at least a day prior on 240v makes a lot of differerence.

These fridges work well when they are full of cold stuff so I tend to fill it well in advance. The 'thermal massing' effect of cold items in the fridge works wonders. If there are any spaces I find filling them with beer works very well!
 

mikerezny

Well-Known Member
Sep 11, 2016
782
1,403
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65
Mount Waverley, VIC
#5
Hi @Chris Daly,
welcome to the forum.

You have asked an important question.

I can explain what we do.
Firstly, regarding running the fridge on 240V to cool it down before you head off.
In the cooler months, I usually only put it on 240V first thing on the morning before we leave. That means it is on for 2-3 hours.
In the hotter months, I might put it on 240V last thing before going to bed at night.

Regarding running your fridge on 12V. This topic comes up quite a lot and if you search through the forum you will find it has been discussed many times.
It is definitely not recommended to run your fridge off the battery in the van (house battery). On 12V your 3-way fridge will draw between 15A to over 20A depending on the rating of the 12V heating element in your fridge. My 90l Dometic RM2350 has a 175W element and draws 15A. Other fridges have larger wattage heating elements.

A typical house battery has a capacity of 100Ah. The fridge will completely flatten the battery in around 5 hours!

On the morning before leaving, I also fire up the fridge on gas to make sure it is actually working. On one occasion we loaded up, drove off and arrived at our destination 6 hours later to find we couldn't start the fridge on gas. Turned out to be a faulty gas regulator.

The way most people work to run the fridge on 12V is to run it from the tug but ONLY when the ignition is on. That means running wires from the battery on the tug back to the towbar but also installing, up near the battery, a fuse or circuit breaker and a relay to disconnect the feed to the fridge when the ignition is off. This is important since you don't want the fridge flattening your tug battery when the engine is not running, such as stopping for an extended lunch, OR forgetting to switch the fridge over to gas or 240V when you arrive.

There are two ways to connect the battery to the tug at the towbar.
1: Use the heavy 35A connectors in the 12-pin plug. This is now the standard way Jayco do it.
2: Many have had problems with the pins in the 12-pin plug heating up and melting the plug. So. a more accepted way is to connect the fridge via a standard Anderson connector.

Many people have issues with running the fridge efficiently on 12V. It is imperative to ensure the size of the wiring is adequate to supply the 15-20A needed by the fridge AND the voltage drop across the cable run is low enough that most of the power gets to the fridge and is not dissipated in the cabling. 8B&S or 8AWG is the minimum. Many people run 6B&S or some even 4B&S.

I hope this helps you get started. Don't hesitate to ask questions if what I have written doesn't make sense or you need further clarification.

The information I have provided above was mostly obtained on this forum over the past 9 months. Back then, I like you, was also new to caravanning. Back then I couldn't even spell caravnner, now I is one!

cheers
Mike
 
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Drover

Well-Known Member
Nov 7, 2013
7,295
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Cooloola Coast, QLD
www.expandasdownunder.com
#6
Yep to all the above, better to run a large fridge for 2 days before departure with cold stuff inside then you can get the whole cabinet nicely chilled down, the 12v is will only keep the temp it won't pull it down, so don't open the door a lot when you stop for lunch...if in cold places doesn't matter......and if you forget to turn the 12v on don't panic you will hardly notice any change...
 

Bluey

Well-Known Member
Mar 31, 2014
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victoria
#7
I run mine through the 12 pin never gets hot every time i feel it used bigger wire for the power an expert wired it up for me and a red ark system under the bonnet that cuts power to van when i turn car off never had any problems with it all
 

relgate

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Feb 2, 2012
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Sydney, NSW
#8
Thanks for that relgate. It does not have a Anderson plug for fridge. I was told you could get a fridge switch when stopping for lunch etc. is it worth setting up the Anderson plug for the fridge or shall I just see how it goes on our first trip? Thanks in advance.
There are a number of schools of thought on Anderson plugs and wiring. Ive never felt the need to upgrade ours from factory plug and wiring. We are not in the top end but have had good success travelling up and down the east coast. I have installed an external fan on mine with a thermo switch
 
Nov 30, 2016
77
65
18
Sydney
#10
All the above -- and we have found it useful to buy a bunch of plastic boxes that will fill as much of the fridge space as possible so that as you use up items there is no increase in the free air apace that will dump the cold air straight out whenever you open the door.
 
Oct 22, 2017
1
0
1
36
Brisbane
#11
Hi everyone,
Another question for you guys. How flat does the van need to be? I park my caravan on my driveway and it's on a little bit of an angle. The fridge isn't working at all. I have two thermostats in there and they don't move when fridge is on 240v I'm hoping it's the angel and not something more serious.
Thanks
 

chartrock

Forum Patriarch
Staff member
Sep 26, 2010
5,534
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Gold Coast Hinterland
#12
Welcome @Bigdiggs22, the fridge will not work if it is not if it is not level, although it will depend on the angle of the van. It can accept a small deviation from level so a pic of how far out your van is in its home position will give us an idea of whether or not it should run.
 

Bluey

Well-Known Member
Mar 31, 2014
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victoria
#13
I park one side of my van on some timber to lift one side to make it level 220 wide by 35mm makes it level perfict too easy
 

Boots in Action

Well-Known Member
Mar 13, 2017
624
618
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Ferny Grove, Queensland
#15
I must admit i have never had a problem with this and van has not always been flat, not on a great angle but certainly not totally level ground. This is on both Gas and 240v
Hi @1DayIll, you must be within the limits of operation to be working satisfactorily. @Drover has it pretty correct for normal operation as "no more than half a bubble either way". I think I remember reading that the tolerance is max 6 degrees from vertical in van (top to bottom) and only 2 degrees from horizontal ( side to side) in van. If you look at how the fridge works, it needs to be nearly horizontally correct for the liquid refrigerant to be able to flow across the top and down through the tubes. It won't flow too well up hill after condensing into a liquid after heating from the boiler. Vertically it is not such a problem as liquid is still able to work its way to the bottom for reheating. In fact, continuing to use heat absorption fridges when well out (horizontally) will cause damage as boiler is continually heating the same mixture of refrigerant and NONE of the condensate ammonia is able to run across the top tube with all the bumps in it, and so run down and mix with the hydrogen to absorb the heat in the freezer and then the fridge itself. The heat just builds up in the empty tubes and affects the chemicals in the tubes. Have a look at the Utube site for heat absorption refrigerator operation for the full story.
 

Crusty181

Well-Known Member
Feb 7, 2010
4,682
10,383
113
Mentone, VIC
#16
I must admit i have never had a problem with this and van has not always been flat, not on a great angle but certainly not totally level ground. This is on both Gas and 240v
Ive found the same thing @1DayIll. I intentionally setup slightly tilted both front up and awning side up. Even with the knowledge " flatter is better", Ive had the van camped up unavoidably on some horrendous angles to the point I needed carabiners to get from one end to the shower, and velcro just to stay on the bed; but thats not ever bothered the performance of the 2 150 Dometic fridges Ive had. (from reading @Boots in Action's info I may well be damaging the fridge, but on every occasion the fridge still performed flawlessly. I otherwise would expect reduced absorption function would/should dramatically reduce performance???, which in my case hasnt)

Another point worth that's seems to plague everyone but me is the 3 way fridges performance on 12v. We had a glorious 6 year run with the single door150ltr Dometic 3 way in the previous van. So impressed, we opted to run with the identical fridge in the new van. Both the previous and the current Dometic 150ltr 3 ways worked very very well on 12v, in fact our cabinet temp will regularly be cooler when we pulled in the arvo than when we left in the morning. Maybe we're just blessed .... we also have one key that opens every Expanda lock (I know that will annoy most :D)

Hi @1DayIll, you must be within the limits of operation to be working satisfactorily. @Drover has it pretty correct for normal operation as "no more than half a bubble either way". I think I remember reading that the tolerance is max 6 degrees from vertical in van (top to bottom) and only 2 degrees from horizontal ( side to side) in van. If you look at how the fridge works, it needs to be nearly horizontally correct for the liquid refrigerant to be able to flow across the top and down through the tubes. It won't flow too well up hill after condensing into a liquid after heating from the boiler. Vertically it is not such a problem as liquid is still able to work its way to the bottom for reheating. In fact, continuing to use heat absorption fridges when well out (horizontally) will cause damage as boiler is continually heating the same mixture of refrigerant and NONE of the condensate ammonia is able to run across the top tube with all the bumps in it, and so run down and mix with the hydrogen to absorb the heat in the freezer and then the fridge itself. The heat just builds up in the empty tubes and affects the chemicals in the tubes. Have a look at the Utube site for heat absorption refrigerator operation for the full story.
Ive been hearing about out of level fridges not working for many many years. Ive not previously taken too much notice of that because from my own experience my fridges have always performed identically at any angle. Im very interested in what you've added here and damn it, I'll now need to check that You Tube stuff @Boots in Action.
 

Boots in Action

Well-Known Member
Mar 13, 2017
624
618
93
Ferny Grove, Queensland
#17
Ive found the same thing @1DayIll. I intentionally setup slightly tilted both front up and awning side up. Even with the knowledge " flatter is better", Ive had the van camped up unavoidably on some horrendous angles to the point I needed carabiners to get from one end to the shower, and velcro just to stay on the bed; but thats not ever bothered the performance of the 2 150 Dometic fridges Ive had. (from reading @Boots in Action's info I may well be damaging the fridge, but on every occasion the fridge still performed flawlessly. I otherwise would expect reduced absorption function would/should dramatically reduce performance???, which in my case hasnt)

Another point worth that's seems to plague everyone but me is the 3 way fridges performance on 12v. We had a glorious 6 year run with the single door150ltr Dometic 3 way in the previous van. So impressed, we opted to run with the identical fridge in the new van. Both the previous and the current Dometic 150ltr 3 ways worked very very well on 12v, in fact our cabinet temp will regularly be cooler when we pulled in the arvo than when we left in the morning. Maybe we're just blessed .... we also have one key that opens every Expanda lock (I know that will annoy most :D)



Ive been hearing about out of level fridges not working for many many years. Ive not previously taken too much notice of that because from my own experience my fridges have always performed identically at any angle. Im very interested in what you've added here and damn it, I'll now need to check that You Tube stuff @Boots in Action.
Hi @Crusty181 , I did some more research late last night and found this interesting article, which gives the reasons for NOT operating your 3 way fridge outside the limitations set down by manufacturer. Firstly, the more level, the more efficient - proper operation!! Secondly, to ensure NO misunderstandings about vertical and horizontal levels, when you stand in front of fridge facing door, you are looking at the VERTICAL angle and that angle is not as critical and allows 6 degrees plus or minus off absolute vertical. Still facing the door of fridge, the HORIZONTAL angle refers to the sideways positioning of fridge ( towards the draw bar and/or rear of van). This angle is CRITICAL and only allows absolutely flat, plus or minus 3 degrees!! Thirdly ANY operation outside these close tolerances WILL cause some sort of long term damage, however slight to start with, but increasing and accelerating with time as dry crystalline particles in top tube attract more small particles (it is how/why crystals grow!). Personally, I make my van as close as possible to ultimate to get the best out of its operation. To not do so reduces efficiency AND causes the start of "future" problems. I decided to print and scan the following article to make it easy for members to read immediately and save them having to wade through a lot of data on Utube. Of course, all those interested are encouraged to do their own research. Ignore the warnings at your own peril!!! Try Google - absorption refrigerator angle of operation.
 

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Boots in Action

Well-Known Member
Mar 13, 2017
624
618
93
Ferny Grove, Queensland
#18
Hi everyone,
Another question for you guys. How flat does the van need to be? I park my caravan on my driveway and it's on a little bit of an angle. The fridge isn't working at all. I have two thermostats in there and they don't move when fridge is on 240v I'm hoping it's the angel and not something more serious.
Thanks
Hi @Bigdiggs22 , you will have BIG problems if you continue to operate your fridge on power or gas if you are well outside the limitations of proper fridge operation. The fact that the fridge appears to be not working at all is a good indication that the ammonia gas when changes to liquid is not passing through the heat exchanger at the top of the fridge and not even getting to the evaporator. All you are doing is stuffing your fridge, a problem that is irreversible. Take the time to view my most recent posting about the warning on how level your absorption fridge must be. Suggest that you do not operate fridge until you are able to get van within the proper limits. Good luck!!
 
Likes: Bigdiggs22

mikerezny

Well-Known Member
Sep 11, 2016
782
1,403
93
65
Mount Waverley, VIC
#19
Hi @Crusty181 , I did some more research late last night and found this interesting article, which gives the reasons for NOT operating your 3 way fridge outside the limitations set down by manufacturer. Firstly, the more level, the more efficient - proper operation!! Secondly, to ensure NO misunderstandings about vertical and horizontal levels, when you stand in front of fridge facing door, you are looking at the VERTICAL angle and that angle is not as critical and allows 6 degrees plus or minus off absolute vertical. Still facing the door of fridge, the HORIZONTAL angle refers to the sideways positioning of fridge ( towards the draw bar and/or rear of van). This angle is CRITICAL and only allows absolutely flat, plus or minus 3 degrees!! Thirdly ANY operation outside these close tolerances WILL cause some sort of long term damage, however slight to start with, but increasing and accelerating with time as dry crystalline particles in top tube attract more small particles (it is how/why crystals grow!). Personally, I make my van as close as possible to ultimate to get the best out of its operation. To not do so reduces efficiency AND causes the start of "future" problems. I decided to print and scan the following article to make it easy for members to read immediately and save them having to wade through a lot of data on Utube. Of course, all those interested are encouraged to do their own research. Ignore the warnings at your own peril!!! Try Google - absorption refrigerator angle of operation.
Hi @Boots in Action,
thanks for the informative article. I am with you, I keep setup the van to be as level as possible. As you stated, the, 'horizontal' is the most critical for correct fridge operation, but is always the easiest to achieve since it just means adjusting the jockey wheel.

Just a further note. This all only relates to the operation of the fridge when stationary. When traveling, this is not relevant since the ups and downs, and rocking of the van all ensure that the operation of the fridge does not result in the buildup of crystals.

Hi @Crusty181,
I agree completely with your comments regarding operation on 12V. I have around 13.8V at the fridge terminals and my experience is that the fridge is colder after we have been driving including stopping along the way to take breaks for lunch or exploring. Since I have a temperature gauge always measuring internal fridge temperature I can be absolutely sure of this observation.

I suspect some of the issues people have running on 12V had are due to too low a voltage getting to the fridge, either due to thin cabling or low voltage due to the smart alternators on newer vehicles OR historical: some early Dometic fridges had a lower wattage for 12V heating element than the 240V element. For instance, the early RM2350's had a 125W 12V element (175W for 240V). Later models have a 175W element for both 12V and 240V. So, the 12V performance on the later models should be no less than the performance on 240V.

cheers
Mike
 

bigcol

Well-Known Member
Nov 22, 2012
6,813
10,159
113
Swan Valley Perth
#20
hmmmmm
I've never "ginned" around with making better cabling for the 12V side
even in the hottest summers of the Pilbara, I used to just run the fridge on 240v a couple of days before hand (with it full of food)
and wait till I get to where I'm going to re-set for gas or 240

1 day driving from Carnarvon to Exmouth (46* outside temp)
I think it lost maybe 2 or 3 degree's from the morning

come to think of it - since 2013, I dont recall using my 12v on the Van fridge...............

(I also have a 40L & 30L engel usually running on 12V while travelling - one freezer one fridge........)