# adding an extra 12v socket and what is this?



## stevegos (Jun 23, 2013)

Hi

I am adding an extra couple of 12v sockets for phone charging etc.

I have bought the sockets and a 7.5A fuse to protect it.

The nearest 12v supply is the leisure battery itself so I though I would connect it straight to that. .

The leisure battery appears to connect directly to a small circuit with a 30A fuse and a relay. See the attached photo.

First question is what is this relay circuit for? I did wonder if it is some form of isolator when the battery is charging?

Second question is if I connect my new 12v socket direct to the battery will it cause problems with say a mobile phone that is connected (on charge) if the battery is also charging?

The motorhome is question is a Burstner i572, 1998 model.

Any ideas?

All help greatly appreciated.

Steven


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## safariboy (May 1, 2005)

I don not know but it is likely to be either the 12V fridge relay or the split charge relay. Probably the former. Possibly both in one relay - 70A would be enough and I cannot think why you need two relays.
You would have to follow the wiring to find out.
It looks part professional and part amateur (the white wire) so beware!


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## Penquin (Oct 15, 2007)

I do not know but wonder whether it is the relay so that battery only is charged when the engine is running? This prevents the starter draining the leisure battery and ensures that the leisure battery gets a charge when it needs it.

I may well be totally wrong, but all MH have such a switching device to isolate the leisure battery from the vehicle and also another such circuit to isolate the fridge 12v supply so that it can only function when the engine is running.

I am sure someone will come along with a much better (and probably more accurate) thought, but that would be my initial thinking.......

Dave


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## stevegos (Jun 23, 2013)

Thanks. Your replies prompted me to do a quick Google search and I found a wiring diagram (in French).

The relay also has a feed in from the starter battery and then an output that also goes to the fridge so that makes sense now.

I also wondered about the two white wires but they have Burstner printed along the cable so perhaps they are original!

So my question still remains as to whether to connect my 12v socket to here or find a different connection which is after the 12v control box which is where most of the other 12v stuff connects to?

Steven


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## safariboy (May 1, 2005)

I still find it hard to believe that the white wire is original. The joint looks poor, the type of wire looks like mains lamp flex or loudspeaker cable, and a two core cable seems to be being used as a single wire. Perhaps it has had to be replaced in the past.
If the fridge is at all modern it may require a permanent 12V feed. (Mine does).
Your original question. There is no reason why you should not connect near the battery, but make sure that you put a fuse very close to the take off point. The disadvantage is that most of the connections round there will be quite large wire. It is not always easy to make a good firm connection if you have very different sized wires. Where the wire goes through anything put a grommet to prevent the insulation wearing.

Connecting onto internal wiring has the disadvantage that motorhome wiring is only just big enough for its design current and extra could cause it to overheat and catch fire.


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## 747 (Oct 2, 2009)

A lot of Burstner wiring is white, 2 core cable. One core will have a coloured stripe to denote it is the live feed. Plain white is normally the negative side.


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## Spacerunner (Mar 18, 2006)

I'm sure your motorhome has a 12 volt socket already, most probably for the TV.
So why don't you buy a multi-socket from Halfords. The sell a twin socket with integral USB socket plus a retractable micro-usb lead. It also has a battery condition indicator and pretty blue led,s.
With one of these you can charge almost anything.


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## brynric (Oct 17, 2009)

I'm with Spacerunner on this one. I was thinking of hard-wiring in extra sockets but in the end an Aldi extension enabled me to have 3sockets and 2 USBs up to 2meters away from the original at little cost and virtually no inconvenience.


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