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Topic: Clarification of power systems

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larkspeednl

15/7/2014 at 7:54am
Location: Emmen The Netherlands
Outfit: Home-Car Eureka 43

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I am totally new to Caravaning and this has me stumped.

I know that most modern caravans have 2 power systems in them the standard 220v system and a 12v system with a leisure battery to operate things like the fridge during transit.

These vans usually have either the old 7S 7N system or the newer 13 pin system for connecting to the car.

This is where my confusion comes in.

Our van a 1988 Home-Car has no leisure battery and only a single 7 pin plug to the car.

There is however what looks like a power distribution unit under the sink in the van.

It's labeled Calira HVS 30 Automatic.

and according to what i could find out about it, since all info I could find was in German, this unit is supposed to pass the 12v feed from the car through to the 12v system in the van, but as soon as it is plugged into 220v mains power it is supposed to auto switch and cut of the 12v feed from the car and produce 30 amps of 12v power and pass that through to the internal systems instead.

I have read that pin 2 (blue wire) on the 7 pin connector can be used for either fog light or aux power so i'm assuming that it pulls the power through that pin.

All that being said I would have expected there to be a leisure battery somewhere if they have installed a system like that in the van.

Can anyone clarify some or all of this for me.

trog100

15/7/2014 at 8:31am
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there is no permanent power to the van from the car with the 7 pin plug.. you ether need another grey 7 pin plug for van power or the newer 13 pin plug..

the fridge is powered from the car during transit.. not from the leisure battery.. the wiring is set up this way..

a newer van has a mains transformer which can also power the 12 volt system on the van without the leisure battery.. it also charges the leisure battery if one is connected..

a fridge consumes a little too much power and would soon flatten the leisure battery which is why its not permanently connected to the 12 volt system only when the car is providing alternator power..

it all a bit complicated and needs a bit of study to figure it out properly.. :)

trog

albee

15/7/2014 at 10:55am
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Hi, on early caravans no rear fogs were fitted and pin 2 was used to supply 12v to caravan. however once rear fogs were fitted then pin 2 was used to power them and an extra socket and plug was needed the 12s. If your caravan has no rear fogs than you could use pin 2 to power 12v to caravan but that would be at risk of flattening car battery. but if rear fogs are fitted then law says they have to work from the car. IT would be easy enough to fit an auxiliary battery into the caravan.

saxo1

15/7/2014 at 11:07am
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A lot of foreign caravan don't have leisure batteries.
If you usually have EHU then there isn't any need for one
If you do decide to fit one you would need a charger and also somewhere to fit the battery.
saxo1

larkspeednl

15/7/2014 at 12:48pm
Location: Emmen The Netherlands
Outfit: Home-Car Eureka 43

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Not sure we are going to fit a battery in this van or not.

Placing it would be easy there is a storage locker under the front bed that has more than enough room to hold a battery box with room to spare.

As far as the wiring goes I've just spent the morning figuring it out and putting it right because someone before me made a right balls up of it.

The entire 12v system now works properly and I hooked up a 12v power supply to earth and pin 2 on the 7 pin plug and sure enough the 12v system came alive.

The corresponding pin on the car socket however seems to be dead it does not operate with the key or the fog lights.

To use the fridge in transport I'm going to have to wire pin 2 to power from somewhere, preferably controlled by the key.

I'll probably install a relay near the car battery to pass power directly from the battery to the van but only when the engine is running.

Jax365

15/7/2014 at 3:28pm
Location: south cheshire
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You don't actually need to use the fridge whilst in transit - unless you're going abroad, though.

I freeze whatever I can for the coming days, chill the rest, and transfer it to the fridge on the day I go, complete with a couple of freezer blocks. This in effect, turns the fridge into a coolbox, and is ok for around 6 hours of traveling for me.

-------------

LlaniDavis

15/7/2014 at 4:27pm
Location: Llanidloes Powys
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We do as Jax does, and as long as you keep the door closed it will still be frozen after 12 hours.

trog100

15/7/2014 at 5:31pm
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to get power from the car a live cable needs running from the engine bay to the boot area.. mostly anyway which is why you wont find a live connection wired in on the car socket..

if youwnat car power to the van its best to wire in another plug and socket.. i just did mine my truck didnt have the extra van power socket..

trog

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