Battery Systems - Caravan v Car Hook up

[Merlin53]

Just purchased a new Swift Alpine with the new power system. Have read all the literature that came with the 'van, but I have a problem with the electrics when the 'van is connected to the car. The lighting panel denotes that both the van battery and the car battery are 'live', but I cannot get the panel to accept the van battery to run the 12 volt system when the car is stationary and not running.
If I remove the van socket from the car, all 12 volt systems are working as normal. Anybody got a solution? Or is it meant to be like this?

 

[WoodlandsCamper]

It's meant to be like that.

 

[Dustydog]

It's meant to be like that.

to stop the car battery draining and leaving you stranded.

 

[Merlin53]

Many thanks folks for the replies, so problem solved. I would comment that as the caravan 12 volt system is fitted with LED lighting, it seems a retro step that you have disconnect the caravan from the car if you are stopping for a few hours rest and a sleep. Can't see how the LED's would flatten the batteries if they were only on for a 1 hour max, (Is this progress?).

 

[ProfJohnL]

Hello Merlin,

Dusty's answer is only part of the story.
Yes it will help to prevent draining the car battery, but as you point out with low energy systems that extends the point at which the car starting may be compromised.

The more important reason is that many cars now use a 'canbus' or similar system to send messages to systems around the car, the EU are concerned that some of the systems now fitted into caravans if left on whilst connected to the car could compromise the safety signals used in the car. One could argue the cars signals could interfere or damage some items of equipment in the caravan also!

Their solution is to fit a disabling relay (Habitation Relay) in the caravan that isolates all the nonessential equipment in the caravan from the running gear when connected to the car.

It also reduces the possibility of a spark occurring inside the caravan when filling the car with fuel.

 

[Merlin53]

Many thanks, you think the dealers would be aware of this condition and inform clients at the handover stage. I spent many hours pondering over the Swift owner manual, but could find no reason to see that I should disconnect the electric plug from the car to get the inboard lighting system working.
It was pouring with rain when I finally gave up and disconnected the plug from the car. I was elated that we had the 12 volt power restored from the leisure battery, but not knowing about this 'safety system' was really annoying. Maybe this post will help others who think they have the same 'problem'. Thanks again!

 

[Gafferbill]

Merlin53.........you may find reading this link useful as it is a guide to caravan electrics.

This is the best guide I know of as regards caravan/vehicle electrics.
For what it is worth I do not think you should have to disconnect the connecting lead in order to use your caravan lights etc when stationary with the engine turned off.
The author of the quoted article is also of the same opinion.

I would have your tow bar wiring checked.

 

[Sproket]

Merlin53.........you may find reading this link useful as it is a guide to caravan electrics.

This is the best guide I know of as regards caravan/vehicle electrics.
For what it is worth I do not think you should have to disconnect the connecting lead in order to use your caravan lights etc when stationary with the engine turned off.
The author of the quoted article is also of the same opinion.

I would have your tow bar wiring checked.

That's a well written article ......

I have never had any problems with switching the power on when the van is still connected to my truck, maybe it's because i decided to fit a dedicated wiring harness ?

 

[Merlin53]

I have read the articles and unfortunately I am more than ever 'confused.com'.
Witter fitted my tow bar and electrics, which worked perfectly on my previous van, and checking with several of my fellow caravan friends they say that ALL post 2014 caravans need to be disconnected from the car for the internal 12 volt system to work, It means that you cannot run the caravan system from your car battery as a 'stand alone' system.
I guess on the odd occasion whilst we are on long journeys and need an overnight stop, I will just have to disconnect the lead to the car!

 

[Gafferbill]

Merlin53.........do you know about Swift Talk

This is Swift Caravan's own forum..........their staff will answer technical queries and you could get a definitive answer on there.

Please let us know what they say if you do contact them!

 

[Craigyoung]

Hi , just to join in the confusion , we are goings to France soon , via the eurotunnel , so when on there , what should I be able to use in our caravan when I want a brew , should the kettle work , the microwave ? And I take it I need to unplug from the car . . . ? :huh:

 

[Damian]

Reply from Sargent:

" With the car connected, do you notice on the control panel that both the Caravan and Vehicle battery LEDs are flashing?

The system will switch off all habitation 12V supplies when the car is running, with the exception of the fridge. This is identified on the control panel by the flashing of both battery LEDs. This also shows the unit is in split charge mode (I.e. Charging both batteries from the alternator)

If the car is hooked up, but the engine not running, and the system is flashing both LEDs then somehow voltage is present on pin 10 of the 13 pin connector. Pin 10 is the fridge line which the caravan PSU uses to identify that the engine is running.

If the engine is not running you should have no issues using 12V in the van. "
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The problem then seems to be the car wiring, with maybe the fitter bridging Pin 9 to Pin 10 instead of running a dedicated feed for the fridge.
Pin 9 is the permanent live(which also provides permanent 12v to the fridge electronics), Pin 10 is the fridge live.

 

[Gafferbill]

Hi , just to join in the confusion , we are goings to France soon , via the eurotunnel , so when on there , what should I be able to use in our caravan when I want a brew , should the kettle work , the microwave ? And I take it I need to unplug from the car . . . ? :huh:

.........you will not have a supply of mains electricity and any gas supply in your caravan must be turned off and is liable to inspection.
Basically all you will be able to do is find something to amuse yourselves for the trip!

 

[WoodlandsCamper]

Basically all you will be able to do is find something to amuse yourselves for the trip!

But don't forget to put the steadies down first.

.... and put them up again before you drive off.

 

[Gafferbill]

The problem then seems to be the car wiring, with maybe the fitter bridging Pin 9 to Pin 10 instead of running a dedicated feed for the fridge.
Pin 9 is the permanent live(which also provides permanent 12v to the fridge electronics), Pin 10 is the fridge live.

Vehicle electrics are very difficult to diagnose and explain on a forum..........what Damian has written here is exactly what I would suspect to be the case if owners have to remove the 13 pin plug to get 12 volt systems to work in their caravan when the tow car's engine is not running.
They should not have to.......... the most likely fault is incorrect wiring of the vehicle towbar.

 

[Merlin53]

Hi Damien, Thanks for the post. I never travel with our fridge on (12 volt supply), so I am at a loss how 12v power from the car can effect the system if the ignition in the car is off, and the fridge is off.
How also can 12v power from the car battery get to the fridge?

 

[Damian]

If the supply to pin 10 is taken from pin 9 as has been suggested as a possibility, the habitation relay will sense that voltage and shut all other 12v systems apart from the battery charging and fridge power circuits which will only then become active when the engine is started.

The fridge heating element should never be able to draw power from the car battery, it is only a supply to the electronics board that remains live so that you can select which power source to use.

 

[SirRogerFFS]

Its not so many days ago when we had this discussion.I did post to say a fellow caravanner had just had a towbar fitted and when plugged into tow vehicle all 12v was dead apart from the fridge.I have to say all the vans we have had have worked this way.Gaffer bill posted .....The Road Vehicle ( Construction and Use) Regulations 1986 Regulation 60-Radio interference suppression.To thin it out a bit it basically says while in transit all 12 volts internally will be dead .Prof L made a good point that a caravan that had a live circuit within the caravan a spark set of a fire in a filling station. Im happy with my van having nothing live while Im towing I have no need to worry about unhooking when we stop for a break.
By the way Im not trying to cause trouble here I just thought it was a point worth bringing up again
Sir Roger

 

[Merlin53]

I started this post due to the fact that I stopped for an overnight stop, didn't want to unhook the car and electric cable, just wind down the steadies, and jump into bed. Unfortunately, after a lot of 'hassle' with Swift manuals etc, I gave up, and in the pouring rain, disconnected the car lead. Success, the 12v leisure battery system was up and working. The forum has been really helpful, no I haven't got the system working yet. As many of you point out, the electrical 12v system is complicated on the car and the caravan.
What now, While I now know that I have to disconnect the caravan lead, I think I will 'call it a day', and hope that the next time I do one of these stops, its not raining.
Am I happy camper with this state of affairs in 2015, not really, but hey ho, there are other things to get on with.
In conclusion, many thanks to the forum for all your help.

 

[Gafferbill]

What now, While I now know that I have to disconnect the caravan lead, I think I will 'call it a day', and hope that the next time I do one of these stops, its not raining.
Am I happy camper with this state of affairs in 2015, not really, but hey ho, there are other things to get on with.

..........that is a shame.
I repeat it is very difficult to solve a vehicle electrical problem on a forum.

However the most likely fault causing your problem is12 volts being present at pin10 in the electrical socket of your towbar.
There should only be 12 volts present at pin 10 when the vehicle engine is running or the ignition is switched on.
You can test for this yourself even if you have no electrical knowledge.

Here is a wiring diagram of the socket of your towbar.

With your car engine and ignition turned off test for any voltage across pin 10 and pin 11.
You can do this with a test bulb or a multimeter.
I suspect you will not have a multimeter so get yourself one of these vehicle circuit testers they are cheap and always useful to have.
I made my own test bulb for pence and always carry it in my car.

If you find a voltage across pin 10 and pin 11 then that is your problem.
Remember there should only be a voltage across these two pins when the vehicle engine is running

 

[Merlin53]

Many thanks, will do at the weekend. I do not have a multimeter but I do have a 12v bulb connected up that I use to see if circuits are 'live', so will have a go
Watch this space!.

 

[Gafferbill]

..........so what happened?