You can have all the plugs, but it depends how it is wired. 

It is always best to keep the fridge well stocked with plenty of thermal mass (liquids!). If the fridge is off for a few hours driving or overnight it won't matter. Assuming it is a compressor fridge (two way).

Ideally the setup would have the car charge the caravan battery, with DC-DC charger (to up the voltage due to resistance because of the long wiring run from the engine bay) near the caravan batteries.

There should be enough amps to charge the batteries & run the fridge. Then switch over to solar when you arrive.

But it all depends how it is wired & what controller you have installed.

If it was a compressor fridge they use about 3.5 to 5 amps while running & only run about 15 - 20 minutes every hour, less at night.

A 3 way fridge you will need to run a dedicated cable from the engine bay to the fridge. Also it needs to be heavy enough gauge (calculate wire resistance) to minimise voltage drop, then you need a DC-DC charger near the fridge/battery to up the voltage. 

3 way fridge use about 12 - 15 amps continuously, so the wrong fridge to run off 12 volts other than when the engine is running.

So if the cable run is 12 metres, that is 24 metres for both + & -  6awg (American Wire Gauge) 13.3mm² for calculating resistance, & it still has a voltage drop of 0.475 volts. The DC-DC charger will fix that.

It sounds like your car will not be wired to run a three way fridge.

Visit an auto electrician and ask him to sort it out and to ensure your brake controller is correctly fitted.

I *strongly* suggest you do not run a three way fridge via a standard 7 or 12 pin caravan connector for the very technical reason that these connectors are utter crap. Instead fit an ignition dependent Anderson connector whose sole task is to power the fridge.

ALAW_Perth wrote:

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Hi all Picking up our first ever caravan next week and this is my first post so I may have some dumb questions If I'm towing without an Anderson plug will my fridge still be working? It's a standard 7 pin connector on the car and I do have a solar panel on the van. I assumed this would enable the fridge to stay powered using the 12v, but I'm not sure.

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For a new caravan the manufacturer will generally give you the information of what is required in terms of a 12 pin connector on the car, grey Anderson plug, a red Anderson plug and brake controller.  I would contact them and get it in writing of exactly what you need as it is no good just going to an auto electrician and asking for a 12 pin plug or an Anderson plug.

An example of this is that I have a 12 pin plug which one of the pins is wired as an ignition sensor for my 3 way fridge, a grey Anderson plug to provide power to a Redarc Manager 30 and a red Anderson plug for the electronic stability control.

Tim 

TimTim wrote:

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 as it is no good just going to an auto electrician and asking for a 12 pin plug or an Anderson plug.

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I would expect any half way competent auto electrician to sort all that out for the customer. If the customer has to act as liaison between caravan company and auto electrician he's in a heap of strife.

I missed that you had posted the make and model of the van.  I see that an optional upgrade is 

• 95 amp hour deep-cycle battery with built-in charger/transformer & retractable 10 metre lead.

Find out the make and model of the built-in charger/transformer.

Before I picked up my van I was given specific specifications of the wiring and connectors I needed on my tow vehicle.  If I had gone to an auto electrician it would have been a simple process of handing them a sheet of paper of what was required.  As it was I did the installation myself. 

That will save you $60 per fortnight in the outback.

Let us know what model & see if your off-grid network needs a bit of fine tuning.

3 way fridges & obsolete today.

We only have a small compressor fridge, but we can go a week on batteries due to inclement weather.

If you tend to move often then the car can charge up the batteries. If you stay put for a week or longer, then you may need a bit more solar & battery resources. Often a simple thing can solve a lot of problems.

ALAW_Perth wrote:

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Sounds good I will upgrade to lithium at some point and could also add an extra solar panel down the track. A lot to think about but that's the fun of it I suppose

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 Paul, for the sake of a one off cost, I would definitely get an Anderson plug installed. Most new vans have one wired on the A frame, either thru solar or battery charger, be a waste if you didn't use it.

Cheers Bob

ALAW_Perth wrote:

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Sounds good I will upgrade to lithium at some point and could also add an extra solar panel down the track. A lot to think about but that's the fun of it I suppose

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 If you have the payload nothing wrong with lead acid.

I did a spreadsheet for every last item including power cables for mobile phones etc. I thought we would be ok as we were careful what we carry, but was horrified to find out we were over our payload. It is frightening how all the little things add up.

Since you are starting with a clean slate it will be the easiest opportunity to weigh everything on the way in!

ALAW_Perth wrote:

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Sounds good I will upgrade to lithium at some point and could also add an extra solar panel down the track. A lot to think about but that's the fun of it I suppose

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 Then you will be hooked and want more solar panels, then more batteries, then more........

ALAW_Perth wrote:

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Hi all Picking up our first ever caravan next week and this is my first post so I may have some dumb questions If I'm towing without an Anderson plug will my fridge still be working? It's a standard 7 pin connector on the car and I do have a solar panel on the van. I assumed this would enable the fridge to stay powered using the 12v, but I'm not sure.

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ALAW_Perth wrote:

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It's actually a compressor fridge I have discovered, draws less amps so that's better isn't it?

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Being a compressor fridge it will operate on both 12v & 240v. 

With a single solar panel on the roof of the van there will be some charge going into the van battery (provided the sun is shining) whilst you are travelling. Whether it is sufficient to keep your battery topped up (so it is full when the sun goes in that evening -to get you through the night until the sun shines the next day) will depend upon the the wattage of the panel. 

It will help enormously if you put already cold stuff into the fridge, & pre-cool it all on 240v before leaving home. 

A single solar panel will be marginal at best. In overcast/poor solar weather it is better to have more panels to get the charge in. 

Reason for anderson plug connection is to utilise charging from vehicle alternator to van battery as you drive. A DC to DC charger mounted in the van (& fed from the anderson plug) - close to the van battery is best. (a slightly controversial statement to some - but that is my experience - especially in regard to longer battery life) . 

Main reason for more solar on the roof is to enable you to remain camped in one spot for longer periods. If you always move on daily & drive for long enough to recharge the van battery from the car (once anderson plug is fitted) then you have less need for additional solar, but having the solar gives you the freedom to stay longer without driving with the van in tow.  People vary in how much extra solar they fit, but essentially if you ever want to stay stationary for more than a few days you need sufficient solar to keep you powered indefinitely. This is often referred to as a 'balanced system'. ie. Without driving you have sufficient solar to return your batteries to 'full' (ie. to the solar regulator's float mode) *every* 24 hours, whilst using the appliances you need. 

Most people find having the charging from the car/anderson plug very useful as it allows you to reach camp with van battery(ies) as fully charged as possible. 

Having a good regulator/battery monitor  with a readout of battery voltage is very helpful. 'Familiarity' is the key. Get used to looking at it regularly so you learn the system's 'norm' so you know if anything is ever amiss. If you get up in the early hours for a 'call of nature', before sunrise this is an excellent time to check battery voltage with a glance as you pass the readout. (Less useful after the sun has risen). 

Solar panels are relatively cheap these days. Within reason as a general rule it is better to have more rather than less solar. Too much solar on a sunny day means some input isn't needed & just gets wasted, but on overcast days it ensures you are more likely to get what you need.