When traveling I don't connect my 190lt Dometic 3 way with 12v. Don't need all the voltage problems, I just throw 4 or more freezer bricks just before I leave home, fridge cold. I've taken my freezer section out and just use it as a fridge only. I have an Engel 40Lt in the front boot of the caravan run by solar, dedicated freezer. Re freezing ice bricks as needed. the 3 way fridge runs better now I have taken out the freezer section. I'ts a ST rating fridge 10yo. works good now it doesn't have to worry about keeping the freezer section cold. With ice bricks it keeps it cold for about 4 hours on road, 3.8 deg not opening the fridge. when I get to destination bricks still 2/3rds frozen. I only stay in caravan parks.

msg wrote:

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Solve the whole issue.
Get a one way fridge (12v compressor)
Turn it on. Set Temp forget.
Always copes with ambient temp. (High or low)
Always Works. After 10yrs use by me I can vouch for that.
What do you need? Solar panels. Good Batteries, preferably lithium.(LifePo4 not other, The PO4 ones are not sensitive to heat and unlikely to catch fire)
When you are driving the engine will generate electricity and top up the house batteries as well as the vehicle.
When the sun shines, the sun will charge the batteries through the solar panels.
When it don't shine the lithium batteries should be large enough to keep the fridge going for some time. Can't say how long because I haven't run out)
You can also plug into shore power to charge your batteries or.. run the engine (not recommended to idol but in emergency worth risking),
Savings on gas will pay for itself fairly quickly.

No swiching over etc. Set and forget.

-- Edited by msg on Thursday 6th of June 2024 02:12:42 PM

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When my 185lt 3way fridge, which currently works perfectly in all modes, finally carks it I will definitely upgrade to a 240V/12V compressor fridge.

But until then, fingers crossed.

deleted ... misread the last comment.

-- Edited by Are We Lost on Thursday 6th of June 2024 06:56:15 PM

DI think we are talking at cross purposes Dick0. Seems you are talking about 3way fridges with 240v. switch overs on gas and I am talking about 12v system where there are no switch overs.

Di, you didn't say how old the fridge, van is - the fridge may need some maintenance done on it.
Added to my comment above, I also added a Fridge Switch into the wiring so that when the van stops moving, the 12v feed is disconnected to the fridge.

Yes, I had some hiccups with the 3-way in our Eagle camper but after adding fans that operated off a small solar panel when we were stopped & shading the side wall where the fridge was, we had no further problems.
The fridge in our current van is excellent, bearing in mind that we live in the tropics too. It is not one of the more desirable "T" fridges either! On hot days I still shade the fridge area of the wall but haven't found room for the fans yet.
We continue to use the Esky bag on all of our outings to keep our morning tea, lunch cool. whether we have the van with us or not.

Yes, I'd like a nice compressor fridge but I don't want to be carrying more batteries, solar panels either!!

The subject of improving the performance of 3 way fridges was always a popular thread on here in years past.  A search of previous posts will reveal a mountain of information.

I used to be rather over focused on the subject, but after implementing a range of 'improvements' my issues are largely solved.

My troubles started when I requested an increased size of the T rated 3way fridge during build, but Jayco failed to raise the exit vent resulting in the vent being level with & not above the top of the fridge - Some people overcome this by putting a spice rack on the top of the fridge to allow an extended cavity & installing a larger top external vent.  Another solution would be to revert to an old fashioned ceiling/roof vent arrangement.

 

The sorts of things that I did to try to overcome the incorrectly installed fridge in my Westport van.- 

- Baffles across the rear of the fridge (on the external cladding) directing the air flow to against the rear of the fridge rather than it flowing up the easier path of the outside wall cladding.

- Stuffed insulation in all the spaces at the side & top of the fridge cavity

-Ensured that the gas chimney top was secured so that it always vented out of the top vent.

- Switch controlled fan at bottom forcing air up the rear of the fridge & a pair at the top sucking air out of the cavity.  Don't be too aggressive with the fan strength.  Size & location is critical so that normal air flow is not impeded.

- Fitted a curved panel at top of the fridge to help the vertical air flow to change direction to out of the top vent

- small computer fan inside the fridge to direct a gentle stream of air over the cooling fins at the top rear of the fridge section.  It switches off when the door is opened.

- I use a number of labelled plastic containers to store food types in the fridge. Thay take up most of the space & I loose very little air when the door is opened.  I cool them & their contents down in the Engel when restocking the fridge.

- Installed an internal external thermometer to monitor the fridge performance.

- Modified the wiring (Larger) so that when towing the Tug alternator charges direct to the fridge via a relay off the accessory switch in the tug.  Meanwhile the Solar charges the van battery.

- When stationary & not connected to 240v, I run the fridge on gas, even when stopping for morning tea or reversing on to site & setting up.

- Of course, I run the fridge off 240v at home for a week before setting off on a trip & load it up with stuff at least 3 days before setting out

 

That's all I can think of off the cuff.

 

A lot of trouble I suppose that could be eliminated by a good 12/240v compressor type installation.

-- Edited by Cupie on Monday 10th of June 2024 12:39:49 PM

-- Edited by Cupie on Monday 10th of June 2024 12:43:45 PM

Cupie wrote:

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The subject of improving the performance of 3 way fridges was always a popular thread on here in years past.  A search of previous posts will reveal a mountain of information.

 

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 Hi Cupie,

Some good and efficient improvements to the 3 way fridge.

I assume your fridge does not have AES (Auto Energy Select) and must be manually selected.

Mine has AES so when you turn off Tug ignition the fridge will automatically switch to gas after 15 minutes. Then automatically switches to 12V when tug ignition turned on.

Also, fans to extract air from top vent is all that is required to move air and extract heat. I have 3 x 120mm computer fans secured with cable ties to top vent controlled by selectable adjustable thermostat and they just fit neatly in the vent.

I have made many, many improvements to my Den with efficiency in mind and with an emphasis to off grid free camping. I will post all the improvements in "Show Us Your Rig" in the coming weeks with Pics and Text explanations to support.

Happy travels.

With good lithium and solar I can run the Engel as a freezer and freeze coke bottles (.really good of you can get All frozen with onshore power before leaving, I even freeze lots more at caravan parks when I stay, also freeze your food in van parks then I use an everkool esky for food and drinks and just swap one or two coke bottle from esky to freezer every day or two. Works great.

When we bought our motorhome it came with a 3-way AES Thetford 2-door fridge which seemed to work ok, but we discovered just before the second outing that it had stopped cooling very well. We decided that it probably wasn't worth chasing it up with the dealer we bought it from, mostly because of time constraints.

12v element resistance: present, not open circuit, assume it's ok. 240V element was the same. Gas burner doing its thing, exhaust not blocked, plenty of heat coming out of the exhaust. One suggestion was to take a drive on a fairly rough road in the hope of shaking loose some of the corrosion inside the cooling circuit. This didn't work.

After a fair bit of reading we decided it must be one of two possible problems, since everything appeared to be doing what it was supposed to do.

1) Due to inactivity, oxides had blocked the liquid path in the circuit and turning the fridge upside down for a while would help by unblocking these and allowing them to settle.

2) Heat transfer compound between the refrigerant tubes and the heatsinks inside the fridge had deteriorated, reducing thermal conductivity.

I initially turned the fridge upside down for 30 minutes (recommendation was for 24 hours). After righting the fridge and reconnecting it, the refrigerant tubes (which I'd exposed by removing the heatsink) began to get noticeably cold within 30 minutes so I left it and next morning discovered the tube frozen. This allowed us to feel fairly confident about the trip we were about to take, but were resolved to invert the fridge for the full 24 hours afterwards (I couldn't delay the trip, I was working at the Bathurst 1000 race). Removed the old heat transfer compound which was dried up and replaced it with computer CPU cooler grade thermal paste.

After returning from that trip, I removed the fridge again and inverted it for about 36 hours.

I've since removed the freezer's heatsink as well, discovering that the heat transfer compound had similarly deteriorated. Having replaced that, we now have a perfectly functioning fridge and are not (immediately) looking to replace it with a compressor fridge.

I have replaced the fridge in a previous caravan, which had a non-tropical Electrolux 90L 3-way fridge. After spending a night in the desert where the coldest it got was 33C (no joke) and the inside of the fridge was 15C, we ripped that fridge out and installed a Waeco CR140. The opening was almost identical (2mm taller than the Electrolux) so it was an easy install. An upgrade to the cabling from the battery and this was a perfect solution (replaced 6mm with 21mm cable, voltage drop reduced from 1.7V to 0.4V over the cable length).

We'll likely do the same if this 3-way gives us any further grief, but I'll need to add a battery bay for another 300Ah LiFePO4 battery and add more solar to the roof.

The takeaways, for me: regularly use the fridge, so that large oxide deposits can't form and block the path and if any decline in performance is noticed, check the thermal compound.

Hello Members:
I've read all posts of this thread.
I was looking for information as to why when I connect 12 volts "directly to the back" of my Dometic 2553R fridge it will not draw any power.
I suspect the 12v side is blown or some thing like that, maybe the 12v switch at the front? I will look into it further tomorrow. I only found this out today I am going through the caravan testing certain aspects of it. I bought it last week.
This fridge does work on LPG gas and 240 volt.

However in reading the lack of efficiency with these absorption fridges, I reckon 2x 40ltr Engel fridges with the dual zone attachment would be the best option for me. I already own one and I can buy another one.
If I can't find or fix the 12v side of it, I will consider removing the fridge and use the space for the Engels.

As most of you know the Engels don't draw many amps and are pretty robust / plus portable if needed.

Anyway thinking out loud .. thank you for all the generous information.

-- Edited by Dtassie on Monday 15th of July 2024 09:19:26 PM

Welcome to the Forum Dtassie, the 12v side of the Dometic fridge are tricky to wire up, go to a Dometic Supplier to correctly sort it out.

If it's an AES fridge (Automatic Energy Switching), hooking up 12V to the fridge alone won't be enough. There'll be another pair of wires permanently connected to the house battery for fridge management.

If it's a manual energy source selection fridge (has a dial on the front which you need to set manually to each source), it won't have that management circuit and SHOULD work when connected (and switched to battery!), so testing the resistance of the 12V heater element is the next step. The resistance you should find varies from fridge to fridge but it's going to be very small (under one ohm).

Fast way to find ohms needed: look inside the fridge (probably near the bottom) it should tell you how many watts the fridge draws. Divide 144 by the watts to get the resistance.

Slow way (to get the same answer): work out the amps by dividing the watts by the volts. Now divide the volts by the amps to get the resistance.

Working example (both ways): "My 12V element uses 200 watts"

Fast way: 144/200 = 0.72 ohms

Slow way: 200W/12V = 16.666A, then 12V/16.666A = 0.72 ohms

-- Edited by Outback_Tourer on Tuesday 30th of July 2024 07:58:03 PM

elliemike wrote:

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12v supply to the 3 way fridge while travelling  is never efficient,  but  it can hold temp in the fridge. That it if the van (fridge) can be kept level.

This is not possible it the van is already not level when on a level road on the hitch.

Then roads, even what appear to be flat roads undulate.

Up or down hills and the van is not level.

These absorption fridges require the fridge to be within + or - 3 degrees of being level at all times to work efficiently

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 Hi Mike, 

I have constantly achieved a drop of up to two deg in our 3 way dometic. This is after I wired a direct Anderson feed from the Jeep battery/75ah relay using 8 bns to the 12v connection of the fridge.

Also the eco tourer sits down a bit but does not effect the fridge while on 12v.

 

NB: can top pic be removed, i accidentally uploaded it.

-- Edited by 67HR on Sunday 4th of August 2024 02:59:22 PM

-- Edited by 67HR on Sunday 4th of August 2024 03:06:55 PM

Big Mal wrote:

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The first thing with a 3 way fridge is to check that it has been installed properly, most aren't with poor insulation and venting, the fridge just gets too hot and is working its guts out because of poor workmanship and not applying the makers installation instructions ...

I have pulled out and re insulated a few of them, sealed the area from venting to inside and improved the air flow so hot air is vented outside quickly, the fridge operation after wards is amazing, the recovery after the lunch time door swinging is very fast compared to before, insulating the outer wall now means you notice no difference in the wall temp outside as the sun beating down doesn't cook the fridge as much either ................................... My fridge will hold the freezer at about -13 and fridge at 4c now that it has been insulated and when the fridge is restocked it doesn't take long for the temp to drop back down.

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 A very good post ..thanks