I run an 80 litre fridge in my Landcruiser. I have a two battery set up and the "slave" battery is good for about 12-14 hours before the power drops off. Travelling around that suits me OK as I'm using the vehicle on a regular basis and keep things topped up. Purely for a bottom line consideration I would use the car battery while travelling and the generator for stationary and camping purposes. there are multiples of alternatives for power such as those you mentioned but they all cost money and you say you have a generator already.

Mate i would have all 3 options . Cant fail .

Dual batteries , with the one designated to the engel being a pure deep cycle.

Hook a solar panel up as well.

Then the gen set is a back up and you shouldnt have to run it all the time. I run the gen set during the day and allow the solar panel to charge the battery, then turn off the noisy gen set and switch to battery at night so everyone can get some sleep without a motor running all night .

C-Teck do a smart managment system that would be worth looking at

I had dual battery setup for my engel in my old hilux, always worked a treat, 2nd battery in the tray, i have a red arc isolator and everything to set it up minus the battery if you wanna make an offer on it?

Was only removed due to roll over/write off :(

 A good Duel batery system  added with an arkk pack  portable batery unit with 120ah ATM batery  with a dc 12v charger system should keep your engel going for atleast 4 days  or add a solar panel onto it and will keep it charged also can hook in the generator for backup 

 I set up Hilux up with a dual battery when we traveled round Australia.   Have just set up Triton up with one, you'd be surprised how cheap it is to do if you DIY

 I have a 57L engel fridge / freezer and would suggest a dual battery setup, and run a full tank of fuel through the generator each day, with a large  capacity battery charger charging the battery, and run the engel off the generator at the same time, with the engel cranked right up. If possible a cheap solar system putting something into the battery all day will also help a lot!

 Just fitted duel batts and 80watt solar panel. Had 7 night camping trip and had to drink warm piss after day 4. Luckily the meat was frozen solid first and held on. Dodgy cigarette lighter socket (it was a narva one).. If you go that way do you self a favour and fit Anderson plugs and take the gen set.

 Sounds like most prefer some kind of dual battery setup. 

So what size battery (or batteries ) do i need? What about a isolators/releys/etc? How much would an averaged sized system cost to set up?

Mjohns i probably will take u up on your offer, i just dont know what i need yet, or what to offer you!

 Make sure your wiring is up to scratch too, at least 6mm to the fridge.

Scotto...

I only run a 40ltr engel, but if you have got a new engel since the gold edition, make use of the battery low voltage cut out. Just keep in mind that its set to "off" as the default setting from the factory.

I run duel batteries in all my cars, but in the suzuki, i have "tweaked" the wiring. Ive installed a second battery, moved the alternator cable and starter motor cable to the "extra" battery, then use a red arc solienoid to charge the "origianl" battery. This means no matter how much i party and drink up the beach with the lights and radio on, i wake up in the morning and she still starts every time.

Like others have said, when ya out and about driving make the most of your cars 12Vdc charging system, but when ya running the genny at night time, plug the fridge into the 240vac supply from that.

Your question about the 0.5 - 4.2amps max, and what it means... Basically ya fridge will pull half an amp when everything inside is at the temp your fridge is set to, and its only working a tiny bit to retain that cold temp. As compared to pulling over 4 amps if you drop a carton of hot beer in there and turn it down to get them cold. The harder the fridge works, the more current it will pull.. Rule of thumb would be to stock the fridge up and have it working hard when plugged into the Genny, they have it just ticking over keeping it cool when plugged into the car.

I use a 120 hour deep cycle battery and charge it every 2-3 day.

 We have two 60l ARB fridges - one used as a fridge and the other as a freezer.

We use a dual battery system in the car while travelling. Aux battery for the fridge and cigarette lighter for freezer when travelling. 

When we pull up for the night firdge remains on second battery and the fridge is swapped over to aux battery on camper trailer. 

When stationary both fridge and freezer are moved into shady, cool spot in camp and we permanently connect fold-up portable 120W + fixed 50Wsolar panel to camper trailer battery and fridge and freezer draw from the one battery.

As sun goes down I kick generator in guts for a few hours to boost battery for the night ahead.

Overnight the battery provides power to fridge and freezer before solar panels kick in next morning. 

Spent 4 weeks with this set up at Ningaloo in July and managed to freeze plenty of fish on top of our frozen meat etc we brought up with us.

Works for us.

http://outbackjoe.com/macho-divertissement/macho-articles/design-guide-for-12v-systems-dual-batteries-solar-panels-and-inverters/

if you need a solar panel this is by far the best deal I have come across

I use one of these on my boat at the Abrolhos for my 50L Waeco, had it 18 months and numerous Island runs.

http://www.ebay.com.au/itm/NEW-12V-120W-FOLDING-SOLAR-PANEL-KIT-MONO-CARAVAN-BOAT-CAMPING-POWER-BATTERY-/360466559807?pt=AU_Solar&hash=item53ed7b333f

come round and have a chat mate, we can sort something out

pretty much consists of red arc isolator (6 months old)

wiring to reach tray

and large fuses etc.

all you will need is a deep cycle battery

I have a 2011 hilux that i set a duel battery up in to run my engel and think that would be your best bet.

Rough estimate on prices.

Ctek Smart charge $350ish

Bosch deep cycle N70ZZ equivilant $150ish

ARB Battery Tray $115

Wiring $50ish

Easy as pie to do it all your self.

There are a heap of different setups but the Ctek would be the best for what your doing. Has a port so a solar panel can easily be wired into the smart solonoid to trickle charge batteries. Can jump from aux bat to starter battery if for some reason your starter battery dies.

If your not confident to do the wiring your self you can fit everything in place easy as and then take it to a sparky to do the wiring.

 For an extended trip like yours away from 240V power and the fact you will be using it mainly as a freezer means you'll need something more than just an auxiliary battery which is charged when you run your car.

For example, if you have a 120 amp hour auxiliary battery means you can get approx 60 amp hours out of it (damage the battery if you regularly drop it to 50% charge) before it needs recharging.  Not too sure how many amps your fridge will draw when you're on freeze but factors such as outside temperature, how often you open and close it and whether you will be putting food in there to freeze all make a fairly big difference. And leaving your freezer in a hot parked car like you mentioned will also draw a lot more power.  (there's graphs online somewhere that show power consumption vs ambient temperature)

Say for a real rough example your freezer draws an average of 2 amps/hour (big guesstimate) , over a 24 hour period it will draw 48 amps which is close to 50% of your battery so if you arent regularly putting charge back into your battery then it will go flat in a few days. 

So unless you're doing a lot of hours driving every single day then you'll definitly need a generator or solar panel to provide enough power. Not too sure how long it takes but most people massively underestimate how quickly a vehicle will charge a flat battery.

I have a 180kW solar panel I bought cheap online and put an upgraded mppt regulator on it connected to a 110amp hour deep cycle battery and that kept me going for a week long trip up at Steep point when it was fairly warm. Solar panel was slightly overkill and should have a second deep cycle battery in case of a few cloudy days but it works fine.

Theres a huge amount of info in 4wd and camping forums which can explain stuff a lot better and provide some actual calculations to determine how much power you will need.  Nothing worse than going on a trip of a lifetime and after a few days you cant have a fridge/freezer.

awesome feedback lads. seriously awesome. I knew nothing about this shit 24 hours ago.

after some extensive reading of the links and products provided and suggested, and just general googling, I think I have settled on going all 3.

I will get a 120W solar panel (cheers Rob H), and also install a dual batt setup, using the ctek charger and a 120AH battery. solar charge the batteries when I'm not using the car, and boost with the generator in the evenings, or when needed.

I reckon I can do this all for about $600, and coupled with the generator, should see me through the trip with no power hassles at all.

cheers again, bitchez.