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How do the electrics work in the caravan?


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While the caravan is connected to car incoming 12v circuit i notice not all lights work in caravan for some reason...can you turn on the 240v mains at same time? While connected to cars 12v supply?

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Yes, ok to turn on the mains but you won't achieve anything.  You need to be physicaly connected to 230v before any mains fed items in the 'van will work.

2019 Adria Adora Thames

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In short ,  anything with a plug on is the 230v mains electric, the rest are powered by 12v  leisure battery. The fridge and the heating  and ovens & hob are gas and electric and 12v .

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1 hour ago, joanie said:

In short ,  anything with a plug on is the 230v mains electric, the rest are powered by 12v  leisure battery. The fridge and the heating  and ovens & hob are gas and electric and 12v .

 

No.

When you plug the van into the car a relay (electrically operated switch) in the caravan changes over and all 12V in the caravan runs from the car battery - the caravan leisure battery is isolated. Some items may not work correctly due to voltage drop along the cable from the car battery.

 

When you start the car engine a second relay activates which feeds 12V from the car to the leisure battery to charge it and isolates all 12V from caravan circuits. At this stage the 12V from the car also powers the 12V side of the fridge cooling - the light in the fridge is usually from the leisure battery and/or mains.

 

If you connect mains to the van the power supply or charger will supply all the 12V needs of the caravan and charge the leisure battery at the same time. If you plug in to the car - engine NOT running - at the same time as the mains is on the power supply will charge the leisure battery as they are usually wired in parallel, but all other 12V in the caravan will run from the car. You should NOT connect mains whilst plugged into the car with the engine running as the caravan power supply will then try to supply the car and anything could happen!

The gas ignition is provided by the leisure battery, the electric hot plate on the cooker and the microwave if you have one are supplied from mains only, the fridge works from mains or gas only when on site, and is kept cool by a dedicated 12V supply from the car when towing.

 

Caravan road lighting is supplied only from the car on dedicated wiring and has no connection with the leisure battery or the caravan mains power supply.

 

Edited by Woodentop
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2018 Passat B8 Estate 150GT TDi150 towing a 2018 Bailey Unicorn S4 Seville

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8 hours ago, John1993 said:

While the caravan is connected to car incoming 12v circuit i notice not all lights work in caravan for some reason...can you turn on the 240v mains at same time? While connected to cars 12v supply?

Have you got a battery fitted to the caravan ?

 

Is the van new to you ?

 

What year is the van, some vans have a mixture of 12v and 240v lights, usually two 240v  in the corners at the front window.

 

Wondering why would you want to connect to 240v and the car at the same time, though as others have said it may do some harm.

Edited by Silversurf

Common sense isn't a gift, it's a punishment because you have to deal with everyone who doesn't have it.  :rolleyes:

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Hi, Is it a British van, which uses a leisure battery to run the 12v system, or a foreign van, which may not have a leisure battery, instead depending on its 12v supply to come from a 240v powered transformer??

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On my van when I connect it to the car, other than the fridge none of the 12 volt appliances operate.

Land Rover on SORN so not towing anything for a while

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slightly off topic but I am looking to fit a wireless  rear view camera to my van.  Its a garmin one which transmits to the sat nav.  You have two choices wire into reverse lights so it only activates when you put vehicle in reverse or wire it into constant power so you can toggle between map and camera when driving.  Id prefer to have it on constant so I can see more easily whats behind me when driving. I already have a rear view camera when reversing -  shes call the wife! My question is has anyone wired one in and what would be the best way to wire into constant - would it be the road/marker lights?

 

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11 hours ago, John1993 said:

While the caravan is connected to car incoming 12v circuit i notice not all lights work in caravan for some reason...can you turn on the 240v mains at same time? While connected to cars 12v supply?

sorry john 1993 if I misled you , I admit that I didn't read your post properly 

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1 hour ago, OWOMW said:

On my van when I connect it to the car, other than the fridge none of the 12 volt appliances operate.

When I returned to caravanning some 3 years ago (20 years after my previous caravan and after switching to motorhomes) I too was perplexed by this new fangled 13 pin plug and 12v electrics which didn't appear to make any sense. 

With the previous caravan and two 7 pin plugs everything 12v appeared to operate normally whether connected or not.

So after reading around the subject I think the answer is (but correct me if I'm wrong).

Modern car electrics (canbus?) can be affected by 12v appliances in the caravan.

Therefore manufacturers have taken the easy option to disconnect them all when the caravan is connected and the car engine is running (as an aside it is possible to purchase appliances which have been tested certified not to interfere with car electrics, but in my experience only motorhome converters take this route as the internal lights and auxiliary 12v systems need to operate at all times).

The older separate connections for battery charging and fridge from the car (which operated through a relay when the engine is running) have now been replaced by a single pin (plus earth pin).  

This circuit is also only "live" when the engine is running and carries out 3 functions

- isolating the caravan internal 12v systems (to test leave the porch light on then start the engine)

- charging the auxiliary battery

- operating the fridge if switched to 12v

One other pin in the 13 pin socket (and dedicated earth pin) is permanently "live" and connected to the car battery, but does not operate any caravan 12v appliances and used by the AL-KO ATC controller if fitted.

 

Well, this explanation works for me!

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40 minutes ago, CliveB said:

When I returned to caravanning some 3 years ago (20 years after my previous caravan and after switching to motorhomes) I too was perplexed by this new fangled 13 pin plug and 12v electrics which didn't appear to make any sense. 

With the previous caravan and two 7 pin plugs everything 12v appeared to operate normally whether connected or not.

So after reading around the subject I think the answer is (but correct me if I'm wrong).

Modern car electrics (canbus?) can be affected by 12v appliances in the caravan.

Therefore manufacturers have taken the easy option to disconnect them all when the caravan is connected and the car engine is running (as an aside it is possible to purchase appliances which have been tested certified not to interfere with car electrics, but in my experience only motorhome converters take this route as the internal lights and auxiliary 12v systems need to operate at all times).

The older separate connections for battery charging and fridge from the car (which operated through a relay when the engine is running) have now been replaced by a single pin (plus earth pin).  

This circuit is also only "live" when the engine is running and carries out 3 functions

- isolating the caravan internal 12v systems (to test leave the porch light on then start the engine)

- charging the auxiliary battery

- operating the fridge if switched to 12v

One other pin in the 13 pin socket (and dedicated earth pin) is permanently "live" and connected to the car battery, but does not operate any caravan 12v appliances and used by the AL-KO ATC controller if fitted.

 

Well, this explanation works for me!

Nearly right, but slightly off. 
The permanent 12v from the car is used for ATC(if fitted) and battery charging (via habitation relay). 
The switched 12v from the car drives the fridge and the habitation relay. 
The habitation relay does two things, it isolated the vans electrical systems, and connects the car to the leisure battery for charging. 
The requirement for isolation of the van electrics is down to some regulation. IIRC it’s something to do with ensuring that the vans electrics cannot interfere with the cars systems. 

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I thought caravans had a relay that you could not draw 12v from the car battery when on site to prevent you draining the car battery thus not being able to start car.

Regards, David
Ford Kuga ST line 2ltr. Diesel 2017,  Bailey Pursuit 11 400/2 2018, Emove em303 motor mover, Hyundai 1000i Generator.

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1 hour ago, David 38 said:

I thought caravans had a relay that you could not draw 12v from the car battery when on site to prevent you draining the car battery thus not being able to start car.

It seems to depend on the van manufacturer. 
My 2018 lunar has a button to permit using leisure battery or car battery. However my daughters 2019 Bailey has  no such option

Edited by Lost in the wilderness
Typo
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1 hour ago, David 38 said:

I thought caravans had a relay that you could not draw 12v from the car battery when on site to prevent you draining the car battery thus not being able to start car.

On my 18yr old Bailey, there is a 3 way rocker switch. 

1 - van battery, 

2 - off

3 - Car battery  (if the car is attached of course).

 

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4 minutes ago, daveat92 said:

On my 18yr old Bailey, there is a 3 way rocker switch. 

 

 

Yes in the past I recall switches but for all my later caravans it as been automatic and only the fridge to select, towing site gas or mains, although I believe upmarket models are also automatic.

Might be the changes came in with 13 pin connections.

Regards, David
Ford Kuga ST line 2ltr. Diesel 2017,  Bailey Pursuit 11 400/2 2018, Emove em303 motor mover, Hyundai 1000i Generator.

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8 hours ago, OWOMW said:

On my van when I connect it to the car, other than the fridge none of the 12 volt appliances operate.

 

Correct but only when the engine is running. If it is not running then all 12V electrics including the fridge light but NOT the cooling should work. If they don't check the fuses, and make sure there is 12V across pins 9(+) and 13(-) on the socket - they should always be live.

 

2018 Passat B8 Estate 150GT TDi150 towing a 2018 Bailey Unicorn S4 Seville

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Just been thinking about this and I recall when we had 7pin connector system we had a special lead when on site and the car battery was used for 12v supply.  But when 13 pin system came in this practice ceased.

Regards, David
Ford Kuga ST line 2ltr. Diesel 2017,  Bailey Pursuit 11 400/2 2018, Emove em303 motor mover, Hyundai 1000i Generator.

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Hi everyone 

I have 2020 hobby caravan bought in Germany  and has no leisure battery fitted. So I'm thinking about adding a battery myself and trying to get live feed from 13pin towcables (orange wire ) and earth and join to battery then I'll get 12v lights in caravan 

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Hobby vans do not have a battery as the power , both 230v and 12v is managed by the power distribution unit.

Some lights are 12v but others are not.

The best advice as it is a new van is to get the correct "Autark" pack and leisure battery fitted by an approved engineer so as to retain the warranty .

If yo udo it yourself and make a mess of it , all the repair costs will be down to you, and if you damage the PSU they are VERY VERY expensive.

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As Brecon mentions, Hobbies don't come with a leisure battery or charge control circuit as standard, so they have a limited 12v supply to the van from the car with engine off, for a few lights, toilet and sink pumps and possibly the ignition circuit for gas appliances, for comfort stops.

 

Yes in theory you could link into this 13 pin plug supply for a 12v battery, but you will still need a charger, the correct wiring, safely locating and monitoring the battery and a good chance of zapping the PSU, which as Brecon says, on the latest vans is very expensive and Hobby are very shy on supplying PSU's , wiring diagrams and other items to Joe Public, only allowing accredited dealers and workshops access to them and instantly voiding your warranty.

 

Yes it's a pain and a price to pay for the extra kit, but would be a great selling point in the future.

 

One thing I can say about the latest Hobbies is that at least they have wiring looms with more than three or four colours  and the 12v system is now all DC, it used to be a mixture of 12v AC and 12v DC as well as 240 v AC, don't ask how I know. 😲🤭

 

I have friends in Sweden and Kauko bought a 2020 model in Germany around mid 2020 and got a free Autark kit before driving it home to Boras, it may well be worth enquiring about.

 

I'll send him an email to see what the deal was and what it entailed but may not receive a reply for a while, he's in the Swedish Royal Navy so vanishes off the radar sometimes.

 

 

 

 

Common sense isn't a gift, it's a punishment because you have to deal with everyone who doesn't have it.  :rolleyes:

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12 hours ago, John1993 said:

Hi everyone 

I have 2020 hobby caravan bought in Germany  and has no leisure battery fitted. So I'm thinking about adding a battery myself and trying to get live feed from 13pin towcables (orange wire ) and earth and join to battery then I'll get 12v lights in caravan 

Hi John, I mentioned the point about foreign vans as we bought a brand new Hobby, in Germany, in 2004 and, like yours, there was no battery.

 

We had considered this before buying and decided it was not an issue as we had no intention of using non electric pitches.
We kept the van seven years, the longest we have kept a van, and it is the only van we have not had warranty issues with.


So, my question is-would be are you likely to use it ‘off grid’ and, if not, is it worth the hassle for any questionable gain??

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On 23/10/2020 at 13:31, Lost in the wilderness said:

The switched 12v from the car drives the fridge and the habitation relay. 
The habitation relay does two things, it isolated the vans electrical systems, and connects the car to the leisure battery for charging. 
The requirement for isolation of the van electrics is down to some regulation. IIRC it’s something to do with ensuring that the vans electrics cannot interfere with the cars systems. 

Lost...

Thanks for the additional information.  Makes more sense.

However, it did get me thinking ...

If the relay for the auxiliary battery charging is now effectively on the caravan side (and operated by the fridge circuit going "live" when the engine is started), does this mean that for those who have an older caravan and have replaced the 7N and 7S plugs with the newer 13 pin plug for a modern car that the auxiliary battery is now connected to the car battery without a relay when the caravan electrics are connected to the towcar?

Edited by CliveB
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6 hours ago, CliveB said:

Lost...

Thanks for the additional information.  Makes more sense.

However, it did get me thinking ...

If the relay for the auxiliary battery charging is now effectively on the caravan side (and operated by the fridge circuit going "live" when the engine is started), does this mean that for those who have an older caravan and have replaced the 7N and 7S plugs with the newer 13 pin plug for a modern car that the auxiliary battery is now connected to the car battery without a relay when the caravan electrics are connected to the towcar?

I don’t think so. The 13 pin has a permanent 12v and a switched 12v. Just as 7 pin has. 
The permanent 12v is what charges the leisure battery, via habitation relay.   The switched 12v drives the habitation relay, and powers the fridge. 

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1 hour ago, Lost in the wilderness said:

I don’t think so. The 13 pin has a permanent 12v and a switched 12v. Just as 7 pin has. 
The permanent 12v is what charges the leisure battery, via habitation relay.   The switched 12v drives the habitation relay, and powers the fridge. 

Although there are standards, they have changed over the years and manufacturers do not always interpret them the same way.

The switched feed from the car is sometimes on if the ignition is on, sometimes on if the engine is running faster than tickover and sometimes only on if a smart alternator decides that it has power to spare.

Likewise there can be different changeover provisions in the caravan.

One of the few consistent points is that the habitation relay should prevent most internal 12 equipment from working if the battery is charging to prevent its use while actually on the road!

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