Charging of battery through cigi lighter outlet

Sorry for my ignorance crackles but where does the $700/800 come into it ?? I like your idea as far as using the duel controller, actually was just thinking before reading your reply would I be able to use the controller for anything else other wise I was going to get rid of it. But reading your reply Im thinking I could use it for charging a battery in the van/jayco when we get it ?? I'm a bit restriced for room under the bonnet for a duel batt set up compared to previous vehicles so was one reason I was thinking of other alternatives.........cheers

75 Ah Thumper would be the smallest size you'd need to run a fridge reliably stand alone. No doubt there are cheaper one's around.
Cheers Craig....

Sounds ideal to me, ours is 50L although we are looking getting another for a freezer but maybe slightly smaller (40L)?? not sure yet. Priced the thumper waeco but stupid me didnt think of asking what amp hour battery they have in them and if it goes bang can you pull it apart and replace with a different battery if required. there is a 4wd show at Eastern Creek soon so will check it out further........Didnt realize you could run from the thumper while charging at the same time..Cheers

I think they are about 40 amp. You can buy a 100 amp deep cycle battery and an Arc battery box for less than the Waeco.
You can also charge on the fly and run the fridge with this set up as well.
Ive run my 50 litre waeco for about 4 days on this set up with carefull use of the fridge

Cheers Ross, this really sounds the go for my use, will enquire on monday and get some prices. what style of battery would be best, taking into consideration the battery will be inside the rear of vehicle next to fridge when travelling ?? I have heard about some battery with glass matt inside ?? sorry but I know minimal about batterys but have always purchased them from battery world here in Penrith but have always just used a cranking battery as second battery and never had an issue, I know they dont last as long as a deep cycle but due to my short runs to and from work then the vehicle sitting in garage for a few days before driving again i just went with cranking. Have done this with 2 previous vehicles but as said very limited with room under bonnet and found that having the second battery under bonnet some times just didnt suit our needs.... Will definately get some form of deep cycle this time though..I like the sound of it lasting 4 days that would be impressive Regards Steve

I was using a 105amp Delkor,it cost around $240. Its a budget deep cycle ,no glass mat ,just thick lead plates.
Getting 4 days out of it means no kids touching the fridge and keeping it in the shade.Turning it off at night also helps.
I also had my fridge hard wired direct to the battery terminals,anything in between robs some power(inc battery boxes)
Its all wired to the cranking batteries in the front via a solenoid that isolates the deep cycle battery when the engine is off.(so you dont have flat batteries up front)
It may be possible to over charge the deep cycle battery but running the fridge while it was getting charge from the engine seem to keep it in the right range.

You can get a wet cell deep cycle at any battery retailer,but as you may have found battery world are not the cheapest.Look for other battery specialists,there is plenty in each city.
You can get the Arc battery boxes from supercheep,$60?
They have a cig lighter plug and other outlets as well a LED battery indicator.

Make sure the battery will fit in the box.
Deep cycle batteries can only be discharged to about 80% of their max charge,any more and you shorten their lifespan(of about 1100 recharges?).
Im not great on electronics either ,so you need to study up on that.