Caravan Wiring

[Robot]

I have just purchased a Navara D22 model and I am going to run 12V to my caravan to run the Fridge while we are driving.
The navara has 2 batteries one that is used to operate the starter and the other to run the accessories.
I am going to put in an isolater and 2 fuses the question is do you need to isolate the batteries in the narvara or just connect the isolater between the accessories battery and the wiring to the caravan I am a technician by trade and can follow ccts etc so is there a diagram available out there that I can read if the batteries have to be isolated.
Robot

 

[s14 panda]

I have just purchased a Navara D22 model and I am going to run 12V to my caravan to run the Fridge while we are driving.
The navara has 2 batteries one that is used to operate the starter and the other to run the accessories.
I am going to put in an isolater and 2 fuses the question is do you need to isolate the batteries in the narvara or just connect the isolater between the accessories battery and the wiring to the caravan I am a technician by trade and can follow ccts etc so is there a diagram available out there that I can read if the batteries have to be isolated.
Robot

Just run the isolator between the car and the caravan, you can get the 12v waterproof plugs from Jaycar, put the fuses on the active just before it leaves the batteries. Just use some orange circ twin in red and black and tie it to your chassie with stainless steel ties, Jaycar has a wiring diagram and all the info its easy!!!

 

[Robot]

Thanks for the reply just another question which applies to the caravan end.
The 12V from the tow vehicle can it be connected straight to the fridge which is directly across the transformer which supplies 12v when the van is connected to 240V on site.
The transformer is a Bainteck SP-200-12 as I don,t have a cct of the transformer I don,t know how the output is wired, I have sent an E-Mail to Bainteck but haven,t Have a response as yet.
Also which or what type of isolater did you or would you use.

 

[happy john]

I can help you with this but need to know what van you have does it have a battery also is the fridge a 3 way dometic? because if you don't wire it properly it won't run as it draws 10amps on 12volt
john

 

[Old.Tony]

Welcome to the forum.

Most 3-way fridges don't use thermostats on 12V operation. We've got a 12V/24V/240V Waeco fridge in our caravan and I even run that on 240V while we're driving so that the house battery is unloaded (for better charging). When we buy our new van, we'll go back to a 3-way and I'll run it on an inverted supply fed from the tow vehicle, because I want the fridge to run on thermostat - it will cool more efficiently.

 

[BravoBrad]

As you are planning to run it whilst you are driving, I wouldn't bother with an isolator, just hook it up.

I wouldn't run it when the car isnt running.

a) It wont run for long if its a 3way fridge, as tony said, they dont run a theromstat and will flatten the battery in a fairly short time.

b) Due to the consumption, and voltage drop, they wont really run that well without the engine going.

 

[Robot]

Thanks for the reply, The van is an Olympic 2000 and the fridge is a Dometic 3 way and there is no battery in the van, I would still like to connect an isolator which would you suggest as there is a chance that the fridge or wiring can develop a short so if you park the vehicle and van the battery will discharge very quickly and the isolator is a safe precaution.

 

[happy john]

OK its simple as tony said these fridges draw huge power one of the biggest problems they are not installed correctly heat build up is a major problem
a computer fan on the top vent will help draw away the heat.anyway without going on i have a coramal off road it has a house battery charged while driving via the anderson plug without seeing your setup iwould suggest that the transformer won't power the fridge on 12volt as normally in van parks ect 240 is available.If i was in your case i would run at least 4-5mill wires from the rear plug to the fridge the teminals are located at the back via the bottom vent
these fridges are designed to run on 12volt while you travel if you ran it on 12 volt whilst car not running battery will be flat in 2 hours.as for isolaters i have duel batts in the 4 cars i have owned i use a simple marine switch not your normal setup have seen so many fail in the bush.I simply run welding cable from main batt to aux with the switch in line when i pull up to camp just flick the switch rear batt is isolated.but i do have volt gauges on both batts.i would say when you connect the fridge check the voltage at the rear terminals while fridge is running anything below 12 volts is no good forget about the transformer any caravan producer wont use this to power the fridge on 12volt ie no thermostat

 

[Old.Tony]

The 12V side is even worse with some fridges - they don't know when to stop.

Let's say we're comparing the following two scenarios for use while on the move, assuming a typical 90L 3-way caravan fridge:

a) 12V from main battery via anderson plugs to trailer and fed directly to fridge

b) 12V from main battery via anderson plugs to trailer into inverter driving 240V circuit of fridge.

For option a, current draw is about 10A = about 120Watts. There's no voltage detection circuit so if you leave your ignition on and get side-tracked, your fridge is sucking away like Debbie and sooner or later your battery is like Dallas (although without the stupid grin). While you're driving, it takes 10A and that's about the same as a SINGLE 130W driving light. There's no regulator, so it won't cool the fridge back down if you open the door.

In option b the inverter will need to supply around 200W (about 16A). The fridge is running regulated for your extra 6A - this is about the power that a pair of 100W driving lights use - so if you stop to grab a cold drink it's not a real big problem. Even better, most inverters have low-voltage cutoff, once they fall below about 11.75V they automatically turn off - which should leave you enough power to crank the car over again and get everything charged up again.

I know 240V is dangerous. But it's bloody convenient!

 

[joe2006]

It's not the volts that kills ya, it's the amps .

 

[Robot]

Thanks again for the replies I have a choice of either the Projecta or powertech battery isolators has anyone used either of these and which one would you recommend.

 

[terryc]

Hmm, my final set up for the fridge/freezer in the CT will finally be;
0: connected across on of the dual starter batteries batteries
1: Manual isolator switch(emergencies and to reset the resetable fuse)

2: Auto isolator. Sends power back to the CT battery when the engine is running and the starter battery has recovered. Can also be switched on manually from cab. the actual one is the basic one on the andersonpower.com.au
3: Resetable fuse.(20Amp)

These are going to be mounted on a plate mounted on the RH side inner wheel arch under the air filter(D22 2010). there are two captive nuts and a usable(?) square hole to give three points of attachment.

4: Wiring to rear(substantial 10mmsq?) I'm planning to run this inside the chassis inside a thick plastic pipe/hose(reduce/prevent rubbing wear).
5: Anderson plug, 50Amp grey from above or other supplier. As I write, the tow bar is off to have a couple of flat plates attached to mount the anderson plug/socket on it (and to fix a replace the hitch lock slack remover nut that was ripped off).

6: Trailer tail with anderson plug to match 5. Tail(both can be made by anderson power on order) goes into CT "power box" and attaches to a;

7: C-tek D250S dual supply battery charger. The other power is dual 12v 120Watt solar panels on the boat rack. The handbook for the D250s says this can be connected in parallel across the batteries with a C-tek mains charger.

8: The CT batteries, two sets, either a pair of ??? GC2 or Trojan T105s. 225amphours each set.
9: Low battery cutout device(from Jaycar). What I need to source is a "alarm/flashing light" device that will work when the power cuts off from low battery voltage, to go with this.
10: Evakool 70L fridge freezer(runs 24v or 12V). Max power is <60watts when it is running on max setting(freezing water).

Hope that sort of helps.