Towing Electrics

[DDJC]

We are looking at towing a small trailer to carry extra gear. One of the things that we want to do is put a small compressor freezer in the trailer and connect it to the trailer electrics.

Do I connect it to 9 & 13, or 10 & 11?

Thanks

 

[pappajohn]

I would put it 10 and 11 as that connections is designated for a fridge already.
No 9 will be on regardless of engine running or not and will draw power from the engine battery if left parked for a period.

 

[David and Sally]

Looks like 9 is a permanently 12v whilst 10 is switched.

 

[cmcardle75]

We are looking at towing a small trailer to carry extra gear. One of the things that we want to do is put a small compressor freezer in the trailer and connect it to the trailer electrics.

View attachment 536757

Do I connect it to 9 & 13, or 10 & 11?

Thanks

It depends on how your electrics are wired. Is this for a motorhome?

10 & 11 would only work with the engine on, 9 & 13 all the time. This is assuming they're wired correctly (they often aren't).

If it was my van, I'd be wiring 9 & 13 up to the leisure battery and use those. This means the freezer stays cold even when you're not driving. However, I wouldn't do it if I hadn't wired it up myself, as it would probably go to the engine battery.

 

[Mikeco]

You are of course assuming that the van socket has been wired up as it would be for towing a caravan which it may not have been. Unless you know that’s the case.

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[DDJC]

It depends on how your electrics are wired. Is this for a motorhome?

10 & 11 would only work with the engine on, 9 & 13 all the time. This is assuming they're wired correctly (they often aren't).

If it was my van, I'd be wiring 9 & 13 up to the leisure battery and use those. This means the freezer stays cold even when you're not driving. However, I wouldn't do it if I hadn't wired it up myself, as it would probably go to the engine battery.

Thanks. There seems to be a mixed feeling about this.

Looking more closely at the issue, so if I connect to the permanent current on 9 & 13, what if you stop on the Autostrada for a well earned prosciutto panini? How long before the leisure battery is empty? We have a solar panel, but I have heard that a permanently connected fridge or freezer can run down a leisure battery inside twenty minutes.

And I thought (could be wrong) that running down a leisure battery to flat, is never a good idea.

 

[DDJC]

You are of course assuming that the van socket has been wired up as it would be for towing a caravan which it may not have been. Unless you know that’s the case.

The lights on the trailer have always worked with no problems, but I have never tested the power take offs. You have a point. I will get the multimeter out and check 10/11 and 9/13, engine on/off.

 

[cmcardle75]

Thanks. There seems to be a mixed feeling about this.

Looking more closely at the issue, so if I connect to the permanent current on 9 & 13, what if you stop on the Autostrada for a well earned prosciutto panini? How long before the leisure battery is empty? We have a solar panel, but I have heard that a permanently connected fridge or freezer can run down a leisure battery inside twenty minutes.

And I thought (could be wrong) that running down a leisure battery to flat, is never a good idea.

That depends on the size of your battery and the type of freezer. Assuming the battery starts 100% charged, I would expect my battery (300Ah Lithium) to run a compressor freezer (say average 24W) for 6 days. If you are running a absorbtion fridge (say 120W) using a 85Ah lead acid to 50%, you have just over 4 hours.

That's assuming no solar. Solar would extend the absorbtion fridge by a few hours, or until evening. It would extend the compressor fridge to around October/November.

 

[DDJC]

That depends on the size of your battery and the type of freezer. Assuming the battery starts 100% charged, I would expect my battery (300Ah Lithium) to run a compressor freezer (say average 24W) for 6 days. If you are running a absorbtion fridge (say 120W) using a 85Ah lead acid to 50%, you have just over 4 hours.

That's assuming no solar. Solar would extend the absorbtion fridge by a few hours, or until evening. It would extend the compressor fridge to around October/November.

Really?
I didn't know compressor fridge/fridges were that efficient.

 

[cmcardle75]

Really?
I didn't know compressor fridge/fridges were that efficient.

My CRX80 averages 12W over a long period. I doubled it for the calculation for a freezer, but this might be pessimistic.

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