3-way fridge and power inverter

Hi,
Our first van had a 3 way fridge which didn't work. The heating element was never installed in rear of unit..
Wired in a new 1 and was ok.
Good luck. Cherry.

Carlo,

I'd suggest you'd need a bloody big inverter, ample battery storage and then have the risk of your Avan being at mains potential while you're driving along.

Those little coolers, fridge is a bit tongue in cheek, are okay as a drinks fridge while travelling, but are very power hungry once you turn the engine off. Also they struggle to keep internal temps low, except in ideal conditions eg. airconditioned car interior. We've had a couple of them and they were handy for cooling drinks while travelling. The cooling fan can be a little annoying too, until you get used to it.

What dramas did you have with the compressor fridge and solar panel?

Bob

Carlo,

I had an Avan Cruiseliner and had the 12V part of the fridge working as well as it can on 12V.

The secret is BIG cable from the tug charging system (preferably via an isolator) all the way back to the fridge in the van.

I used 6B&S to an Anderson at the rear of the car, then re-cabled the van with an Anderson to connect to the car and 6B&S going back to a junction box at a convenient location (under the bed in our case), from which other 12V stuff branched out. I then made sure the cable from that junction box to the fridge was as short as possible and a reasonable size (6mm from memory).

AFAIR that fridge pulls about 12 amps, maybe 15, when on 12V. That causes a big voltage drop if cabling is too small and the fridge wants a good 12V when it is running. 6B&S cabling fixes that.

Cheers

Carlo
I do what you are talking about.
I had a modified sine wave inverter and it played havoc with my HF radio on 8022Mhz.while mobile.
I have swapped it for a 360 w. pure sine from Jaycar and all is good now.
The 240v element in the fridge has a higher heat output than the 12v.
The fridge is now fine and holds the fridge temp from an overnight stop.
The fridge / inverter setup whilst mobile keeps the fridge fluids on the boil whilst mobile and when I stop at the end of the day swap over to gas and there is no recovery time.
I also have a relay installed to switch of the 12v to the inverter when the ignition is off for smoko or shopping in a town. When I am mobile again the inverter comes on.
The current draw is very similar to 12v. but much more efficient.
Stan

Have you tested to see 12v at back of fridge?could be as simple as a broken wire somewhere ,also carefully check the selector knob on the control panel, could be a slight misalignment, when turned to 12v it may be just missing the contact surface in the switch,move the knob a little each way and then try 12v. Keith

Like others have said the issue is most likely your cable size. My 3 way works fine on 12 volt because I made sure the cable was fit for purpose. In fact it will freeze if not watched carefully. I personally wouldn't like to run 240 volt in my van while I'm on the road. I think it's is fairly obvious why.

I bought one of the Waeco CoolPro coolers and again it works just fine as a cooler. It tends to be a bit noisey but it works okay for drinks and picnic items. It's not something I would rely on as a fridge.

Correct me if am wrong but typically the 3 way fridges never worked as well on 12v. Personally I would stick with Gas or buy a compressor fridge for 12v if you don't want to use Gas. The inverter scenario is not worth it vs the option of buying a 12v compressor fridge IMO. Cheers

This hasben dealt with in the past ....... the reality is .... there is no free lunch.

The reason that three way fridges in general do not work well off 12 volts is voltage drop due to cables too small.

therr way fridges run continuoulsy .... they do not stop and start like compressor fridges .... and they simply are not energy efficient.

SO ya have this 3 way fridge sitting there drawing about 10 amps continous and most likly it is a 10 to 15 meters away from the alternator as the cable runs.

if the cable aint big enough the fridge will be prodidgeoulsy inefficient on 12 volts ...... it is that simple.

if you try to run it of an inverter ... that voltage drop will still be there .... and you are introducing extra losses in the inverter ...... if the fridge is operating poorly on 12 volts ... so will the inverter .. if it runs at all.

the answer is heavier cable ...... like starter motor size cable ..... without going into calculations ...... over that distance 10mm2 cable will probably not quite do it .... if you want efficiency ya probably talking 20mm2 cable all the way back to the cranking battery and a 50 amp anderson.

cheers

Three way fridges do work well on 12 V if the wiring is heavy enough. Most tow bar installers only use cable that has about 1/4 of amount of copper in the cable that is required (or probably even less.) Same with the van makers, I am yet to see their wiring that is sufficient for the job. You need 8 gauge cable of bigger to do the job properly.

If the 12 V power cable is not large enough to run the fridge efficiently then it will probably also have too much voltage drop along it to run the inverter as well. First of all upgrade the cable and see if you can make the fridge work properly, if you can do that then there is no point in adding the inverter.

When you have your fridge working properly on 12 V, don't run it off a battery without the alternator running. You will flog the battery too much if you do. I have seen 3 way fridges flatten a Falcons starting battery in half an hour.

Carlo asked if he could use an inverter to run his 3 way.
I answered YES.
Because I use one and it works.
A family member has a jayco swan and it also works for them in practice.
There are probably many others that do the same, we would not be the first.
And the latest chinese made Dometic 3 ways perform better than the made in Denmark ones.
To convert to a compressor fridge of equal capacity with the required batteries (which may need replacing after 4 years) and solar panels will cost in excess of $2400.
Just try the inverter Carlo.