only just getting 12v on camper battery with car running ?

3 ways suck alot of power 12 to 16 amp hour so it's probably for that reason that your reading is not the same, still it should be higher than 11.7 after a 5 hour drive, look at the cable it may not be a true 6mm it may only be 2 or 3 inside diameter and 6mm outside diameter, and your voltage drop is the cause, we got 6mm cable on ours but i made sure the inside diameter was 6mm the wire itself less the insulation.

Oh i'm no expert this is only a guess.

Baz.

Sounds like too much resistance in the power supply cable.

The three way will draw about 10 amps or so off the line on 12 volts

Check out this link. It is fairly long winded but eventually gets to the point.

http://www.fridge-and-solar.net/wire.html

I had the same problem about 2 years ago. Found that it was the earth return to the car. Put in bigger earth and fixed the problem.
Do you have 6mm neg via the anderson plug ?
Vince

yes vince i used the narva two core heat shrunk 6mm positive and neg

I have an almost identical setup to yours in the L/C and I'm getting about 12.2 V at the fridge. I guess it's a function if the length and gauge of cable run from the car battery to the fridge.

There are methods of calculating voltage drop over a given length of cable.
Try this one.

Mike

Not sure if you are testing while running - just a quick point from my recent learnings on that subject area - gotta have the whole lot running when checking voltage levels and drop in cables etc. Re batteries - I think the experts suggest that a group of healthy, charged batteries can all have different voltage levels at rest, for various technical reasons. The camper battery probably never gets the same boot as the front units - and it'd need to be the same type as the front ones, for the comparison to be valid.

I'd be heading down to Jaycar and looking at some 4awg cable. It's think like your little finger. Run both + and - cables. Don't rely on the car body for the earth return and you should find there is minimum voltage drop. Also keep using anderson plugs.
what is the voltage measured with the fridge disconnected?

Leroy

just wondering how hot was it outside and was you fridge and contents chiiled down before you left hme on your 5 hour journey. i have learned over the yers before a trip chill all content down at least 2 days before or longer on 240 if possible or if you load up the frige with hot gear it wiil sux the guts out of your batteries no matter how good your set up is good luck dags

Have you looked at Collyn Rivers Site - very thorough explanation of all things electrical, with a special section on auto wiring to fridges :

From the main page, select 'Fridges - making them work -Part 2'
http://www.caravanandmotorhomebooks.com/articles/index.htm
regards................Keith

Assume there is 8 metres from Main Battery to CT Fridge (or Battery) so you will have 16 metres of wire (supply and earth). If it is 8Ga (4mm diameter of copper) then you will have 16 x 0.0025 ohms = 0.04 ohms. Assume an additional 0.02 ohms across connectors and fuses. Total 0.06 ohms

So at 10 amps you will have a voltage drop of 0.6 volt between Main Battery and CT Fridge (or Battery). If your Alternator can maintain 14.2 volts at the Main Battery, then you will have 13.6 at the CT - enough to maintain charge or slowly charge any battery.

Mike

It's almost certainly a voltage drop problem over the distance. Easiest fix is to "twin" the supply cable to the van, ie run another cable the full circuit and solder both cables at each junction. 3-way are heavy power consumers and are only marginal units on 12v DC. However, they are best on LPG and after all that is what they were designed to do.

Time waster, not really solving your problem, however can I suggest not having the fridge on 12 volt when driving. I reason I say this is that for a 3way to work it has to be level and you will find that as the car is moving it will not be level long enough for the evaporation process to work, thus drawing power for nothing. I would just make sure it is a cold as you can get it overnight and when you hit the road turn it off and it will be like an esky. I am sure if you do a search on 3ways you will find this elsewhere.
As for the battery, years ago I had a similar problem with the deep cycle as the Aux and was told it was because they only accept a charge at a slower rate they need a long time (more than 5 hours driving) to get full once they have gone right down. I now only use starter batteries with a low voltage cut out and have never had a problem.
Cheers Tony.

When most people quote 6mm cable they are meaning that the cable is 6 square mm of area across it, and the actual diameterof the cable is only about 2mm./

In my vehicle we have 6mm diameter wire for both positive and negative and if the vehicle batteries are showing 14 volts the voltage in the van will be 13.8 or 13.9 volts. Our terminals are soldered.

I think most likely cause is undersized cable or poor connections at one or more of the joints.

Brian

Run 8mm cable. This is the size I run on my trailer and caravan for charging batteries though anderson plug. No Problems with running 3way electrolux caravan fridge on 12volt.
Cheers
Charlie

You must use at least 8mm wire to charge a battery in a van.
Jayco now use 2/ 6mm wires one for fridge one for battery.

Hi TW

We have our 50l chestcold mounted in a custom made box on the draw bar, fridge runs on gas even when travelling heat is removed by one of those whirly thingos mounted directly over the chimney. Fridge sits on a slide for access and removal and yes it is all legal checked and approved by a gas guy

TW
Just a thought,the cable has been Soldered into the Anderson plugs hasn't it crimping has its problems!!!

eerfree

Three-way fridges draw 10-12 amps. The existing 6 mm cable is hopelessly inadequate. To do this job properly you breally need to use two twin 8 mm cables. Parallel each cable to give you twon by 16 mm. Overkill? Not if yoiu want that fridge to really perform as intended.
Trust this helps
Collyn Rivers