Car/Van Electrics. How should they work?

[David_374301039]

Hi, When we tow our van to Spain the fridge is working fine on 12 volts. The problem is when we stop to make a cup of tea none of the electrics work in the van unless we disconnect the electrics from the car. Is this how it should be. We have tried all sorts of combinations but nothing works with the 12N and 12S connected. I was under the impression that when you stop you are using the car battery for the van. Could somebody explain to me how it should work. I would really appreciate it.

Regards David

 

[Damian]

David, the 12v from the car will only work with the engine running, as soon as the engine stops, the 12v is cut, to prevent you running your car battery down, and all done courtesy of the Habitation relay.

 

[WatsonJohnG]

Hi David

When you switch on the car ignition it should energise a relay in the car that works the fridge on tow

The lead to the fridge also energises a relay in the caravan called the habitation relay that switches off all the caravan internal 12V except on later vans electronic fridge controls

It also switches the car 12V supply to the caravan to caravan battery charging via pin 4 the green wire

If you can not operate the van internals with the car ignition switched off either your car has been wired without the relay or the relay is faulty

I have met people on rallies who have had flat batteries after a lengthy stop due to a faulty relay causing the fridge to drain the battery

Have a look at wiring diagrams here

www.towitall.co.uk

Hope that helps

 

[David_374301039]

Thank you both for the replies. When I stop the fridge goes off as it is supposed too. Everything seems to be working as it should, apart from there being no 12 volt supply when the ignitiom is off. I will check out the link JohnG. What should happen when you switch off the ignition so that you get 12volt in the van?

Regards David

 

[WatsonJohnG]

When you switch off the ignition the relay in the car to the fridge circuit on pin6 red should open so that no power is going to the fridge and that will allow the habitation relay in the caravan to close and let power from the caravan 12V battery operate the 12V van accessories

If it does this with the car unplugged then it would indicate that the its the car relay at fault

Later voltage sensing relays (eg smartcom) have a small adjusting screw

 

[David_374301039]

Thanks JohnG, I will have to get it checked out.

David