3 way fridge wiring

Member - peter K (QLD) replied:

Hi Bob Most like to run power though an Anderson plug rather than the 7pin plus the right type of cable but these three way fridges don't run very well on 12v they only use 12v for intransit mode but work far more efficiant on gas then 240v then a distant third for 12v PJk Thumbs UpThanks 0

Member - sdr00y (Beecroft,NSW) replied:

Bob, running the wiring through the utilux (or similar) trailer lighting plug will not be suitable. As you point out the voltage drop is too great.

You really need to run a separate positive and negative set of wires to achieve what you want, along with the correct fuses or circuit breakers and connectors (Anderson plugs).

Do you have a battery in the caravan? You could either run the separate set of wires to the fridge or to a battery in the caravan. An extra battery may be of advantage in some circumstances.

Anyway, not being an electrical guru, I am not really sure of the actual size of wire required but something like what Derek sells in his store at ABR. http://www.sidewinder.com.au/page106.html See that link which will show (hopefully) the different wires he sells. I have used some of the twin sheath wire before for running power to the rear of my troop carrier. Email Derek and he will be more than happy to advise I am sure. Something like the TW60 or TW100 will do the job. But check with him for everything you will need.

Lastly, do a search of the forum here. There are many threads asking similar things. Maybe search Anderson Plugs or 12 volt wire or second battery wiring or something like that.

Hope this helps.

sdr00y Thumbs UpThanks 0

Phillipn replied:

I agree with the other reply's. Use wires NO lighter than 6 B & S through an Anderson plug to the van.

Most failures are due to the wiring being too light, causing voltage loss. Thumbs UpThanks 0

Ray replied:

Hi. The first thing that I would do is to check the voltage at the terminals at the back of the fridge. Voltage drop can be considerable.
The second question I would ask is has the c'van a built in battery? If it has have you considered wiring up the fridge to this battery?
What I have done with my 3way is to connect it direct to my batteries in my caravan (150amphr) via appropriate fuses and a relay. This relay is situated between the caravan batteries and the fridge and is closed when the ignition on the car is turned on and the engine running. The activation cables for this relay run via the terminals of a large 7 pin plug. So with my system the fridge runs on 12v only when the car engine is running and by having it wired close to the caravan batteries I am avoiding most of the voltage drop. I have used
8 aswg cable between the batteries and the fridge but the cables from the car to the relay need not be too heavy and should be able to fit in a large 7 pin plug and socket. All cabling is fused both ends.
Before you ask, the caravan batteries are charged from the cars alternator via a relay, in the car, 4 aswg cable and an independent Anderson plug. Also I have a multi stage built in battery charger in the caravan that charges the batteries when plugged into the mains (240).
You must remember to change over to gas or 240 if you have stopped for any length of time. Thumbs UpThanks 0

Member - John and Val replied:

Bob,

As already said, wiring through the 7 pin plug will not be adequate. What you are proposing is quite feasible but will call for heavy wiring (6 square mm or more for both positive and negative) from the front of the vehicle to the fridge. Anderson plug would be far better for the connection between vehicle and van.

Why the heavy cable? To minimise voltage loss - the fridge will draw at least 12 amps continuously and there will be significant losses in smaller cables. The energy reaching the fridge is proportional to the square of the voltage, so even the loss of a couple of volts will result in the fridge only getting 2/3 of what's available.

The other issue to be aware of - as already said, these fridges don't work very well on 12V, not nearly as well as on gas or 240V.

The previous suggestion to put a battery in the van probably won't help the fridge much because of the voltage drop in the cable. Even if this cable is very big there will be sufficient drop to ensure that the battery doesn't get a decent charge if the fridge is drawing current through the same cable. If you do want a battery for other purposes it would be best to run a separate cable from the front to the van to charge the battery. Note that you'll also need a separate relay for this as otherwise the van battery will be connected to the fridge via the 2 lines (from van to front and back to van, unless each has a dedicated relay.)

Hope that makes sense!

Cheers

John Thumbs UpThanks 0

PradOz replied:

Hi - after you attack the cabling size you may find you still have issues with the van manufacturers install of the fridge. Have a read of FRIDGE VENTING. If you fix this and the cable size you should notice a dramatic improvement - cheers....

Thumbs UpThanks 0

Bob48 replied:

Thanks for all the info.

Ill get some larger cable and give it another go.

wish me luck.

P.S. If all fails, and not wonting to throw too many bucks at the problem what would be wrong with travelling with gas running.

I have heard of some people doing this. Thumbs UpThanks 0