Using 3 way fridge

Peter good advice, but the wiring diagram is probably 30 years out of date as it shows the set up for a petrol engine with points and a coil.

That historic diagram (coil/points) remains sound advice today as Peter explained.

3-way fridges are intended for 12V operation ONLY when vehicle is running - as gas is not to be used when mobile for safety reasons. When stationary, GAS is the option to employ unless/until you have AC power available. This becomes slightly problematic when you pull up in a town for lunch/refuel/dump-site/etc as it still takes a sizeable bite out of the battery.

We hired a 3-way-equipped motorhome in Europe (single battery vehicle), and found out very quickly that it didn't function on 12V. Turns out the hirer had disconnected the supply line as he was sick of flat battery issues caused by users who didn't fully appreciate how they should be operated. I reconnected it quick-smart for the duration.

That doesign will work ok if you have a good, charged fresh battery, but may be problematic as batteries age or are not fully charged.

Bettter to use a voltage sensitive relay so the connection is only made after the engine is running. Simpler to wire up too.

I am sure others will comment on the need for decent wiring to reduce voltage drops too.

Nothing wrong with the design, ignition is on while engine is running and off when the motor is not running, how simple is that?

I work on the KISS principle and that is so simple.

There seems to be a fetish for using a device that costs 8 to 10 times the cost of a simple relay by members of most of the forums I frequent. When questioned, they always justify using a VSR to overcome things that are unlikely to happen. In 30 years of using the simple relays, I have never encountered any of the reasons I have posed. When people install a VSR they generally forget the high parasitic load they impose on the electrical system. If you have some of these that have a severe parasitic load then they are worth being replaced with a relay just to reduce the constant parasitic load on the tugs battery.

as Kazza said, KISS is the way to go.

Cheapest solution is not always the best. That's the case here.

I think you will find the parasitic load as you call it is not severe in any decent VSR. In fact most will have standby current of 1 - 10ma. For example the Redarc is <5mA, Vicoffroad 1mA. There are many examples. MOSFET technology has changed things since the ignition coil days.

Standby ( or parasitic as you call it) current is simply not an issue if you know what you are buying these days.

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I agree Tony, you are right. But so also is Peter.
Personally, I prefer a simple relay (or "solenoid") type isolation, but often in modern vehicles it can be difficult to access an "ignition" source for the relay coil and a voltage-controlled relay is more convenient even if more expensive.

Ony IF the system was working well in the first instance. A warm fridge won't get colder on just battery with poor supply.

Gail.
If you have sufficient solar it WILL RUN THE FRIDGE but not at night. Or dull days.

Gail. Best to have that LEAD checked for ability/performance, If it ISN'T a LARGE THICK CABLE it may have too much voltage drop and not really getting the house battery to fully charged when running on alternator.

Hi Gail, the fridge will have 2 separate 12v supplies wired to it. One will be from the van battery and is used for the control side of the fridge. The other is from the car and only is used to operate the heating element that cools the fridge and draws about 15amps hence is only on while the motor is running.

Hi Gail,
The Dometic 3-way fridges are very sensitive to being exactly horizontal so that the absorption circuit works properly. It pays to make sure your van is as level as possible when camping.
I finally got sick of the Dometic 3-way and changed to a Bushman compressor fridge, giving me 130L of storage (as against 90L). The changeover cost about $2k but I now have a fridge that properly freezes and runs off the van battery at all times, and it allows me to free camp for several days without bothering to connect the portable solar panels, or indefinitely with the panels connected and in sunlight.
Keir

"Backing the caravan is definitely a work in progress." And when you get it right first time there's no one looking. Mess it up and everyone in the park is watching . :)
Dave.

Turn left while reversing the van goes right . Mirrors will confirm it. Turn R and van goes left. EVERYTHING IS FRACK TO BUNT.

PS. If it s hot day and inside the van is HOT too, 2 hours is a long time and fridge will rise in temp. Do you have a small 12v computer fan, switchable, to supply cooler air to the back of fridge area so it CAN get rid of heat so it CAN work better? Almost essential if in hotter climate.

I was taught the usual way to reverse both hands on top of the wheel but yrs later a work mate said put both of your hands on the bottom of the steering wheel.
When you want the van to go left raise your left hand and to go right raise your right hand it's so much easier and you never have to think opposite again when reversing.

Yes I have been told that method Of hands on the bottom of the steering wheel But still doesn’t seem to work. I will just have to keep trying. As someone said to me yesterday, by the time I get back from Tasmania, I’ll be all over it. ??????

We did a course with 'Tow-ed' they use a different more 'formulaic' approach for reversing into a site to others. As far as backing goes, I have found the following useful: You imagine that the steering wheel is connected to the back of the trailer by a (big) bowed stick. Turn the wheel to the right ie clockwise and you are pushing the rear of the trailer behind the vehicle (relative to the driver's position). Turn to the left and you are pulling the rear out.
All the while off course checking your position and progress in your mirrors.

Warren. What does that mean? I cannot work out what a bent stick etc means. Bizarre.

RMD, more a bowed stick, a long bow, or perhaps put another way, a length of wood that describes an arc of a circle of an appropriate radius to connect the steering wheel with the rear of the trailer, so just a mental conceptualisation that was used by the trainer that I have continued to find useful if I have a brain fade while reversing the camper.

When refueling the car or ducking into the shops say max around 1 hour we would leave it on 12v but switch to gas if we thought it would be longer as they suck the power. There not the best in summer especially when traveling in hilly areas you get big fluctuations in temps sometimes food would be a bit to warm for my liking and can freeze food in the fridge in winter.
Also my first fridge in the 4wd was a 3 way in the mid 90's but there so outdated these days and 12v fridges don't require constant checking and switching power sources.
My next van will definitely have a 12v fridge for much more stable fridge/freezer temps plenty of solar on roof and at minimum 400ah of lithium batteries and a battery charger to suit. Keep the setup simple for less problems.

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You do WHAT? ……. You light a fire under the fridge to keep the food cold?? Your'e kidding me, right?
Sorry, but what buffoon thought that one up?
I mean really…..? An open flame is it?……. Underneath your refrigerator, right?
And it runs on gas? Well I suppose that's an improvement on kerosene. But not much!
I think you need to look at the calendar. Up at the top it says 2024. Yep, 21st century. We have electricity now and compressor refrigerators. Wonderful things.

Odd reply Allan not sure if it's aimed at someone I expect they know what year it is.

Allan, it is tied up with the development of refrigeration and the timing of the introduction of batteries in caravans. Here are a few snippets gleaned by using Copilot:

"James Harrison (1856): An Australian, Harrison developed the first practical ice-making machine and introduced commercial refrigeration to breweries and meat-packing houses."
These were rather large machines initially driven by steam engines until the event of internal combustion engines later in the 19th century. They were generally found in commercial store rooms and ice making plants. They were far too large for domestic use.

"Household Refrigerators: By the early 20th century, refrigerators became common in households, revolutionising food storage and preservation"
These were still not small units, they used open frame units (as distinct from the sealed units) They were still too large for use in workers cottages.

"Sir Edward Hallstrom (1920s-1930s): In the 1920s, Sir Edward Hallstrom designed and manufactured the first domestic refrigerators in Australia. Initially, these refrigerators used kerosene as a power source. In 1935, he introduced the ‘Silent Night’ refrigerator, which could run on electricity or gas"
These fridges were cheap enough and small enough for the working class. Between the wars, electricity was only used for lights jugs and toasters. The majority of the population did not have electric power, so compressor fridges would have been of little use.

"You light a fire under the fridge to keep the food cold" - yes, that's how the first of the fridges built by Hallstrom worked. They were the old Icy Ball fridges. You lit a kero burner and stuck it under the ball a few times through the day.

"Post-World War II: After World War II, refrigeration technology expanded rapidly in Australia. The spread of electrification and the development of more efficient refrigeration systems made it possible for refrigeration to become a common feature in both urban and rural households."
That was the start of compressor refrigeration in homes. I remember the 1940s fairly clearly, very few households had fridges, the masses still had ice chests.

"Renaissance in the 1960s: Absorption refrigeration saw renewed interest in the 1960s due to the demand for refrigerators in caravans and recreational vehicles (RVs). These systems could be powered by propane, making them ideal for mobile use."
During the 1060s, small size 12V sealed units were not readily available. Also, there was not a ready supply of small size deep cycle storage batteries, Nicads had not become popular and AGMs were still on the horizon. Any 12V systems for vans were mainly for lighting and car batteries were employed as storage batteries. So that is how absorption caravan fridges came about.

Further from Copilot.

The Icy Ball refrigerators were early, innovative refrigeration devices that didn’t require electricity, making them ideal for rural areas. Here’s a brief history:

Origins and Development
Sir Edward Hallstrom (1923): The first Icy Ball was created by Australian Sir Edward Hallstrom. It was a kerosene-powered refrigerator designed to bring refrigeration to remote areas.

David Forbes Keith (1927): Independently, David Forbes Keith of Toronto patented a similar design. His version was later manufactured by Powel Crosley Jr. in the United States.

How It Worked

Absorption Refrigeration: The Icy Ball used a gas-absorption refrigeration cycle with ammonia and water as the working fluids. It consisted of two metal balls connected by a pipe. One ball was heated to drive off ammonia gas, which then condensed in the other ball, creating a cooling effect.

Manual Operation: Users would heat the “hot ball” for about 1.5 hours, typically using a kerosene stove. This process would charge the system, allowing it to provide cooling for the rest of the day.

Impact and Usage

Rural Accessibility: The Icy Ball was particularly valuable in rural areas without access to electricity. It allowed farmers and remote households to preserve food and make ice.

Commercial Success: The Crosley Icy Ball became quite popular in the late 1920s and early 1930s, selling thousands of units.

The Icy Ball represents an important step in the evolution of refrigeration technology, especially in making it accessible to those without reliable electricity.

Is there anything specific you’d like to know more about regarding the Icy Ball or other early refrigeration technologies?

Make a lot more sense very good and informative history lesson Thanks for taking the time.

Thanks for that history Peter. Mind you, I lived through some of that and well remember the stench of burnt kerosene in some houses I visited. And I well remember the instructor's comment near the end of my 1949 refrigeration course………. "And now we come to absorption refrigeration. The best advice I can give you is to take it out onto the back lawn and roll it about for a bit. Put it back and fire it up then come back next day and by the Grace of God it may be working."……….. He was of course illustrating the difficulty of rectifying an absorption system fault and did proceed to instruct on the absorption principles and maintenance of the heating system. But I heeded his disdain.

Sure, absorption refrigeration served its purpose in the last century but it is now really history and perhaps you did not appreciate my humour in the style of Bob Newhart, who is now also, regrettably history.

And Batt's, not aimed specifically at anyone here. Just a generalisation with tongue-in-cheek.

So you have a button down mind, do you? Are you aware that he snuffed it three weeks ago at the ripe old age of 94?

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Yes Peter, I was aware of Bob Newhart's demise which is why I said he was also "regrettably history".
His reaching 94 is maybe evidence of how possessing a good sense of humour can benefit longevity. Hmmm?
But I am at a loss how you deduce that I may have a "button down mind"? Anything but I should think!

Here’s a kero fridge, working it’s little, albeit heavy, heart out in NT’s Victoria River district, 50 years ago.



Fill the tank every day, don’t trim the wick with a knife & only open the door when necessary!
“Rolling around on the lawn” type maintenance was done once or twice a week when we shifted camp. Loaded into the tub of a Landcruiser ute & subjected to corrugations, wash outs & other road hazards.

These days can’t beat a couple of Engels, big battery & plenty of solar.

Bob

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Bob, I can just imagine you lugging that fridge and other essentials around on station work. Tough times.
Mind you, it was 41 years ago that I got my first Engel to replace an Esky. Bonza thing,. even if it did sound like a Mustang taking off!

Allan, as you are a fan of Bob Newhart, I thought you possibly have some of his characteristics. I was just asking. There are the odd occasions when I think like him.

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Pete, I'm just not sure that Bob's public persona was the real Bob Newhart.
And I'm not sure of my own characteristics, other than being a pot-stirrer. lol

"Bob, I can just imagine you lugging that fridge and other essentials around on station work."

Allan, that was the good old days when we made use of what was available. We did not sit around on our hands waiting for something better to come along. That photo is dated 1973, there were no solar panels commercially around then and the only readily available batteries were car batteries. Anyone who had a kero fridge out in the bush thought they were the bees knees.