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Problems with S Plug!

Question

Posted

Doing this on behalf of Terry G.

We have only had our new van (Bailey Pageant Bretagne) from new since 18th March.

Used it for about 2 weeks in total since then.

After our 10 day stint away at Easter, encountered a problem with the lights on the caravan.

To cut is short, took car to where I had the tow bar fitted and found the fuse had blown on the main auxillary electrics and the S Plug on tow bar was melted, so they changed it.

They told me to check the caravan S Plug also which too was melted badly.

Has anyone experienced this and what caused it and are there any solutions to stop it happening again?

Thanks.

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44 answers to this question

Posted

It's the fridge...and there is a fix.

Same thing has happened to mine.

See here for details.

I've yet to fix mine though........... :blush:

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Posted

Sorry I dont know the answer.

However, It's always awkward trying to ascertain whether the fault lies with the caravan or the car.

As Jim has posted, the info from Tony Maris is the best advice you'll ever get in relation to towbars and electrics.

Tony's also a member on here too

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Posted

Cheers guys! :thumbsup:

Still cant understand it.

If this is a common fault, why have the manufactures not adapted the plug to cope with the load that a fridge puts on it during transit?

Is it better not to connect your S Plug whilst travelling?

Does it actually chill your fridge enough during a short journey or is it worth melting it on a long journey?

Its the large black earth cable (centre pin) which is melting.

Terry

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Posted

I still connect it - but I don't have the fridge switched on.

As you say...it doesn't seem to cool much anyway, unless you're on a really long journey. Anything we need to keep cool is in a coolbox in the car, the rest can be chilled when we arrive.

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Posted

You need to chill it first from gas or mains .... 12v is only meant to maintain the fridges temperature.

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Posted

You need to chill it first from gas or mains .... 12v is only meant to maintain the fridges temperature.

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Posted

But Nikki & Willy have a brand new van and a new towcar and obviuosly want everything to work properly.

So, Is the answer to take the van back and say the electrics aren't right. Or, take the car back to the towbar fitter, with the same question ?

I'd start with whichever is the easiest, which'll probably be the car !

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Posted

I would agree with Ron ... car first.

This is not an unknown problem, but I can't remember the cause!

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Posted

I think that basically, the fridge draws to high a current for the 12s plug, the 12n/12s design is pretty poor, from a technical point of view. Fridges, as they've got bigger and better have required more and more power, and basically the design isn't up to it. The suggested remedy in the link I posted earlier is to make a couple of wiring modifications which enables the load to be split between two pins, therefore lessening the risk of the heat being generated to such a level that the plastic melts.

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Posted

I had the same thing happen to ours. When I took it to bits found out that the screw that holds the wire in the plug on the caravan was loose causing it to short and overheat.

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Posted

It's the fridge...and there is a fix.

Same thing has happened to mine.

See here for details.

I've yet to fix mine though........... :blush:

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Posted

But Nikki & Willy have a brand new van and a new towcar and obviuosly want everything to work properly.

So, Is the answer to take the van back and say the electrics aren't right. Or, take the car back to the towbar fitter, with the same question ?

I'd start with whichever is the easiest, which'll probably be the car !

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Posted

:wine:

Hmmmmm ......

It's definitely a 'common' problem BUT not everybody suffers from it ...........

Not using the fridge is unacceptable - it works for some so there MUST be a proper solution !

One thing I've noticed is that there are differing pin designs - some of the male pins are divided into 4 and some only into 2 - I've had lighting connectivity issues in the past when using plugs where the male pins are divided into 4 and have had to splay them out regularly to maintain connectivity ....... it could well be that the fridge connections have the same issues but are not as obvious - until the plug melts !

I succesfully bodged a dual pin connection in my 12S a couple of years ago to avoid any issues - unfortunately we managed to trash the 12S the other week and it got replaced when it was serviced - regretably without the 12S bodge so that's another job on the list before the Loire Rally .....

:wine::wine::wine:

:England:

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Posted

the fridge 12v element has not really changed much in the 10years, its still draws roughly the same amps. the single biggest cause for the plugs melting on pin 7 is a bad contact. this is through dirt or the pin closed. by regularly cleaning the pin and making sure the pin is a tight fit into the car socket, it should stop happening. so make this part of your regular checks along with tyre pressures etc. i have approx 4000 caravans go through my workshop a year, and i would say we see about 15 a yr with melted 12s plug, so in my opinion its not a big problem. but then again i give this advice to any customer who comes to my workshop with this problem so it doesnt occur again.

the only other time i have seen this problem when checking the car side, the earth wire is far too small and usually because the towbar has been fitted on the cheap.

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Posted

:wine:

Cheers Mr S !

Question - what's the approved method of improving the contact ?

I've tended to use a small screwdriver to open up the pins but on two occasions I've managed to break a section of the pin - any better suggestions ????

:wine::wine::wine:

:England:

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Posted

i always use a small screw driver, and have never broken a pin. you just have to be careful. and use emery cloth or sandpaper to clean both the 12s plug and socket on pin 7. dont use any grease/lubricant just keep it clean.

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Posted

:wine:

Cheers Mr S !

Question - what's the approved method of improving the contact ?

I've tended to use a small screwdriver to open up the pins but on two occasions I've managed to break a section of the pin - any better suggestions ????

:wine::wine::wine:

:England:

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Posted

I think this is what is called pin burn out which as I understand is caused by too much current being drawn. I think it stems from the changes made around 1998/99. The link that Jim posted to Tony Maris's website is worth looking at as he shows how to reduce the current going through one pin by sharing the load. It seems that the continental 13 pin system is better but there seems no hurry to introduce it here!

David

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Posted

The problem is caused by dirty pins with a bad contact this causes a resistance and thats what generates the heat and melts the socket I changed to nickle plated plug and socket for the 12s connection, they are about 50p dearer then the brass ones and and have not had the problem since. :yes:

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Posted

Cheers guys! :thumbsup:

Still cant understand it.

If this is a common fault, why have the manufactures not adapted the plug to cope with the load that a fridge puts on it during transit?

Is it better not to connect your S Plug whilst travelling?

Does it actually chill your fridge enough during a short journey or is it worth melting it on a long journey?

Its the large black earth cable (centre pin) which is melting.

Terry

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Posted

im sorry doc but the size of the 12v element in the fridge has not changed in wattage.

so there is no higher powered fridge on the 12v side.

the only higher power is on the 240v where they went form 105w to 125w.

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Posted

I was talking generally 'over the years', Mr. S. rather than specifically about Baileys or any other 'van.

No problems of pin burn-out or voltage drop in the 80's with my Mardon or the early Swift. But as the size of frigs. has increased these problems have become more prevalent.

Although the pins appear smaller on the 13-pin plug/socket connections, pin burn-out is practically unheard of. Voltage drop though can still be a problem as that's down to the car's and 'van's wiring.

According to BS EN1648-1:1997, 'van makers are supposed to limit voltage drop to any fixed appliance to 0.8V, from the 12S plug, and to 0.3V to any battery charger/battery. I just wonder if they up-rate the wiring when they put in fancier frigs/freezers. etc. for their newer models.

So to get 12V, say, at the working frig, you should have at least 12.8V at the 12S (with the frig. ON).

Gives folks some numbers to check out, . . . . .if you've a mind to.

I have checked this a number of times 'over the years', but not recently; think I lost my anorak!!! :laugh:

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Posted

Sorry Mr. Sheens, according to my Dometic Manual the 7390 fridge is 230 ac 125 watt and 12v dc 120 watt. AFAIK these elements are standard in most of the current range of caravan fridges. The cable size recommended is 4mm sq for less than 6 metre run and 6mm sq for longer which includes the car. My van has 4mm sq internal wiring for the fridge and I have wired the car + and - direct (via a relay) from the battery to the socket for the fridge. The fridge interior light and ignition are wired to the caravan battery ONLY as recommended by Dometic. If only U.K caravan manufacturers and towbar fitters would follow suit, but "price rules- O.K." My van is a Hobby.

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Posted

So to get 12V, say, at the working frig, you should have at least 12.8V at the 12S (with the frig. ON).

Gives folks some numbers to check out, . . . . .if you've a mind to.

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Posted

Thats just what my auto-electrician said...

and then proceded to put in bigger cables...

and the it worked.... :thumbsup:

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