No car 12v feed to charge battery on 1993 Swift

[sgtangel]

Hello all,

After making repairs to the 12N and 12S plugs on our 1993 Swift Corvette Diamond (thanks again storm Gertrude), I took the opportunity to hook up the car, and test the supplementary circuits, something I have never had the time to do since we started this whole caravanning rollercoaster

I discovered that, whilst we are getting a constant 12v across pin 4 (green) which I think provides the power to the caravan for lights etc, and an ignition 12v across pin 6 (red), which powers the fridge ?? I am getting no feed, permanent or otherwise, to pin 2 (blue), which I think should be charging the battery when we are driving.
(I had a battery meter monitoring the battery voltage whilst carrying out the checks, and it appears we are getting no charging)

I have checked all the fuses, and everything looks in order.
I then turned my attention to the car, and wonder if the fact that the car has a 13 pin socket, which we access via a 12N / 12S to 13 pin adapter, could be a factor ?

Can anyone advise if a 13pin socket on the car (assuming it has been wired correctly) connected via an off-the-shelf adapter, should provide a 12v feed to pin 2 on the 12S plug ?

Is there something else I may have overlooked in this problem (I am not a qualified electrician, more of a keen DIY`er)

Many thanks

 

[WoodlandsCamper]

Do you have a habitation switch in the van to switch between car and internal PSU for the 12v? If so have you set it to car for towing? The car engine needs to be running (and energised the relay) in order to provide the 12v supply for battery charging/fridge so as not to discharge the car battery.

 

[sgtangel]

Do you have a habitation switch in the van to switch between car and internal PSU for the 12v? If so have you set it to car for towing? The car engine needs to be running (and energised the relay) in order to provide the 12v supply for battery charging/fridge so as not to discharge the car battery.

Apologies, I should have mentioned that - I dont know if it is a habitation switch as such, but the only power switch in the van is a small analogue voltmeter panel with a 3 way selector.

Switch to the left when we are driving
Switch central is off - battery not charging from either 240v or 12v
Switch to the right when on EHU and charges battery.

When I was conducting the tests, the switch was to the left.

Thanks

 

[Woodentop]

Pin 2 might be allocated for battery charging put in practice pin 4 is used - in fact on a caravan of your age it will likely be connected directly to the battery.

Have you checked the earth connections?

 

[Gafferbill]

.........there is no provision on a 13 pin system for battery charging as such.
The modern system utilises the positive supply wire for battery charging via a habitation relay.
The habitation relay is fitted to modern caravans and basically permits battery charging to the leisure battery when the vehicle engine is running but isolates this charging circuit when the engine is not running.
Your 1993 caravan will not have this habitation relay.
You either need to fit one to your caravan together with all the relevant wiring or fit a relay controlled charging circuit to your tow car utilising one of the spare pins in the 13 pin socket.

 

[colin-yorkshire]

hi, the problem is simple, the car has a 13pin socket, so will have the standard pin configuration ,for 13 pin.
the adapter will have the 12N and 12S configuration to suit the post 1998 wiring [so it matches the 13 pin]. your van has the pre 1998 configuration [being a 1993] so the the pin configuration between the car and the van does't match. you will have to rewire the the 12N and 12S plugs of the van to the post 1998 set up or it won't work.as the power going down from the car plug through the adaptor doesn't match the van wiring.

 

[sgtangel]

hi, the problem is simple, the car has a 13pin socket, so will have the standard pin configuration ,for 13 pin.
the adapter will have the 12N and 12S configuration to suit the post 1998 wiring [so it matches the 13 pin]. your van has the pre 1998 configuration [being a 1993] so the the pin configuration between the car and the van does't match. you will have to rewire the the 12N and 12S plugs of the van to the post 1998 set up or it won't work.as the power going down from the car plug through the adaptor doesn't match the van wiring.

Can I assume then that, when new, this van would have charged the leisure battery directly from the car 12v feed, i.e not through a relay, therefore I could re-wire the 12S, adding an ignition 12v to the wire which would have went to pin 2, by perhaps joining it to pin 6, and this should solve my problem ?

 

[colin-yorkshire]

hi, the problem is simple, the car has a 13pin socket, so will have the standard pin configuration ,for 13 pin.
the adapter will have the 12N and 12S configuration to suit the post 1998 wiring [so it matches the 13 pin]. your van has the pre 1998 configuration [being a 1993] so the the pin configuration between the car and the van does't match. you will have to rewire the the 12N and 12S plugs of the van to the post 1998 set up or it won't work.as the power going down from the car plug through the adaptor doesn't match the van wiring.

Can I assume then that, when new, this van would have charged the leisure battery directly from the car 12v feed, i.e not through a relay, therefore I could re-wire the 12S, adding an ignition 12v to the wire which would have went to pin 2, by perhaps joining it to pin 6, and this should solve my problem ?

yes it would, the relay would have been on the car, think they called them smart relays had three take off's a permanent live to feed the interior lights and two that sensed the power drain and cut off the feed if the engine stopped.

you would have to check which wire feeds each circuit on the van and transpose the pins off hand I think the supply feed for the van lights was pin 4 and the charge circuit pin 2 and the fridge pin 6.
you could change the wires over to supply the charge circuit and fridge but remember then you would not have a feed for the lights while the car was stood, as you will not have the habitation relay fitted to the van.

look at this it might help. https://www.volvoclub.org.uk/towbar_electrics.shtml

 

[sgtangel]

Thanks for that - I think I know what I need to do.
First trip away next weekend :woohoo: - will see if I can get it done and working before then.

 

[colin-yorkshire]

Thanks for that - I think I know what I need to do.
First trip away next weekend :woohoo: - will see if I can get it done and working before then.

ok mate good idea, you will see from the illustrations that the pin configuration changed post 1998 [ie from 1999] where instead of the charging pin 2 and interior lights pin 4 the circuits flipped to battery and charge pin 4 and then pin 2 was deleted and left spare, while pin 6 still provided power for the fridge it got it's own earth wire on pin 7.

I AM guessing your problem is the adaptor is supplying charge power down pin 4, and the van requires it down pin 2 and of course because pin 2 was deleted you have no charge power to the van,

let us know how you get on, it is a while since this cropped up think it was twindaddy had the same issue and solved it by moving the power/charge wire [green] from pin 4 in the van plug to pin 2. but check the the power output of the pins on the adaptor just to make sure.

 

[Gafferbill]

Can I assume then that, when new, this van would have charged the leisure battery directly from the car 12v feed, i.e not through a relay

No this is not the case..........when your caravan was new the tow car would have been fitted with relays to automatically switch on and off a positive supply down 2 individual wires to pin 2and 6 in the 12S socket.
One wire for battery charging and one for the refrigerator supply.......separate wires are needed so as to cope with the current demand.
One wire is not sufficient and relays are needed as the current demand can only be supplied whilst the vehicle engine is running.
The relays also serve to protect the wiring during use of the engine self starter motor.

therefore I could re-wire the 12S, adding an ignition 12v to the wire which would have went to pin 2, by perhaps joining it to pin 6, and this should solve my problem ?

No ......you would overload the single wire as explained above.

Your choices are as I outlined in my earlier post......

1. Modify your tow car by adding another relay controlled positive supply through to your 13 pin socket utilising one of the spare pins ........ this may not be advisable depending on your tow car.

2. Fit a habitation relay to your caravan and utilise the positive supply from pin 9 of the 13 pin socket for battery charging. You would need to tap into the controlled supply for the refrigerator to provide a very small current as a switching signal for this habitation relay.

 

[colin-yorkshire]

hi, Sorry Bill that is not right, there is no need to alter the the 13 pin socket on the car as this will be fully wired as per usual specification with 3 power wires and 3 earths, you can add an extra power wire into the circuit using the spare pin 12 [light blue wire] if you require one for some other use, but that is not the issue.

the adaptor cables is where the cross over is done splitting the power cables from 13 pin into 2, 7 pin plugs, at one time when the 13 pin came in think it was about 2007/8 the adaptor cables were available in two types pre 1998 wiring where the battery charging went down pin 2 on the 12s socket.
and post 1998 adaptors [for newer caravans] where the battery charging went down pin 4 on the 12s socket.

the OP has this type of adaptor but the van plug is the other type so when plugged in the charge wire goes down the wrong pin it is a simple as that.

either the adaptor socket or the van plug [suggest the van plug] needs the power pin changing from pin 2 to pin 4 then it should work without any other modifications.

there is a explaination of the two types in this document.
http://www.caravanclub.co.uk/media/1022790/towbar-wiring-mo.pdf
sections 3.2 and 3.3 are the relevant sections.

 

[Gafferbill]

..........but the caravan is a 1993 Swift that is expecting two ignition/ relay switched +ve 12 volt supplies.
One to pin 2 and another to pin 6 in it's 12S plug.
There is one such supply available at the tow cars 13 pin socket at pin 10 for the fridge.
Where is the other?...........I am willing to learn!

 

[colin-yorkshire]

..........but the caravan is a 1993 Swift that is expecting two ignition/ relay switched +ve 12 volt supplies.
One to pin 2 and another to pin 6 in it's 12S plug.
There is one such supply available at the tow cars 13 pin socket at pin 10 for the fridge.
Where is the other?...........I am willing to learn!

pin 9 [orange]

 

[Gafferbill]

Pin 9 is permanent live +ve and is not switched.

If this is connected to the battery charging circuit in the swift you are directly connecting the vehicle battery to the caravan leisure battery in parallel as soon as you connect the adapter.
This is potentially dangerous when starting the tow car's engine.

 

[Dustydog]

I must be missing something here.
Everything Emmo and Bill say is how for 38 years I know things work except one thing.
Now years ago I was told when towing to ensure the caravan battery never linked direct to the caravan unless the engine was running.
So all my tugs from 1978 had split charger relays fitted by me.
A direct live power source is not good practice and I suspect not intended.

 

[colin-yorkshire]

edit, forget it, the wiring is as it is read and learn,

note for the OP, you know whats wrong, but I will let others advise who seem to know better, there is no need for my further involvement, in any way. if you are not sure the advice is correct would take it to an auto electrician and tell him to sort it out, roger and out.

 

[Gafferbill]

.......................don't leave this amiable discussion now Colin we may of stumbled onto something.

I admit my outfit still uses the dual plug 12N / 12S electrics and incidentally on a 1995 Swift that electrically will be identical to the OP's 1993 Swift.
Electrically this vintage of caravan is quite different from today's caravans as you know.
The OP has a newish tow car fitted with a modern 13 pin socket and presumably this is wired using the modern convention to suit a caravan with modern 13 pin electrics.
These modern caravans have a relay fitted to the caravan (Habitation relay) which allows the permanent +ve 12 volts supplied from pin 9 to be used for battery charging but only when the engine of the tow car is running.

Adapters are being retailed to allow an older tow car with 12N / 12S to tow a modern caravan with 13 pin electrics and I can understand how these can work electrically.

Adapters are also being sold to allow a tow car fitted with 13 pin electrics to tow an older caravan with 12N / 12S plugs as in the OP's case.
The OP has found that his adapter set does not provide a battery charging circuit and I do not see how it can unless further modification is carried out to the tow car or caravan.

 

[TD42]

Hi pre 1997 caravans auxiliary 12s (grey plug) were wired differently to post 97 12 s plugs for battery charging & fridge
could your problem be that the car 12s is wired to post 97 requirements ???
see here http://www.watling-towbars.co.uk/wiring_guides_watling_towbars.html

 

[Dustydog]

Colin.
Please don't give up. You are one of the true technicians on here.
There are three issues for me on this subject.
1.The official correct wiring diagram.
2.The OP problem of using an"adaptor"
3. Personal tweaks to try and improve things as I do following the link below.

http://www.towitall.co.uk/faq/1.aspx
I'd like to know more about the OPs car wiring and how it runs into his caravan plugs etc.

 

[sgtangel]

I appreciate all the comments.... and clearly there is a few distinct opinions which provide contrasting thoughts...surely one of the reasons people post topics on forums such as this... to engage discussion and, dare I say it, a bit of friendly banter in the process

to clarify.... I don`t intend to modify my vehicle wiring to the 13 pin socket, as this was professionally fitted with the towbar, by a witter authorised dealer, and I have to assume it is correctly wired as per their guarantee.... If I am to solve this problem, it will be by modifying my van wiring to allow for safe charging of the battery whilst we are towing.

Let me just throw this one out there..... if I was to swap the pins between the fridge and the battery charging, I would lose the ability to operate the fridge whilst towing, but would this ignition 12v feed be sufficient to safely charge the battery ?

Having the fridge operate when towing is not a major criteria for me, and if it solved this issue, even short term, I would alter the plug wiring accordingly. It could always be put back if I was able to find a more permanenet solution which allowed for both

 

[colin-yorkshire]

I appreciate all the comments.... and clearly there is a few distinct opinions which provide contrasting thoughts...surely one of the reasons people post topics on forums such as this... to engage discussion and, dare I say it, a bit of friendly banter in the process

to clarify.... I don`t intend to modify my vehicle wiring to the 13 pin socket, as this was professionally fitted with the towbar, by a witter authorised dealer, and I have to assume it is correctly wired as per their guarantee.... If I am to solve this problem, it will be by modifying my van wiring to allow for safe charging of the battery whilst we are towing.

Let me just throw this one out there..... if I was to swap the pins between the fridge and the battery charging, I would lose the ability to operate the fridge whilst towing, but would this ignition 12v feed be sufficient to safely charge the battery ?

Having the fridge operate when towing is not a major criteria for me, and if it solved this issue, even short term, I would alter the plug wiring accordingly. It could always be put back if I was able to find a more permanenet solution which allowed for both

OK, for the benefit of the OP, do not change the circuitry of the fridge, OR the wiring in the caravan.

it will cause more problems than you could possibly imagine, the problem you have will be in the tails of the adaptor I am assuming the caravan has been used before and the problem arose because you changed the car that has a 13 pin plug fitted, and therefore require to use tails to convert the 13 pin to two 7 pin plugs.

on caravans that were produced before 1998 the 12s plug used pin 2 to provide power to the caravan for both the internal electrics and battery charging, after 1998 from 1999 on, this changed to pin 4, pin 2 was then left unused.

from 2008 the standard configuration is 13 pin but you can if required still have a vehicle fitted with two plugs, this will however be the later specification. I believe your problem is the tails are wired for the later configuration and do not match the plugs on the van, the power wire of the tails [although you must check this with a mulimeter] will most probably be pin 4, while pin 2 will be dead, you need to change the wires round from pin4 to pin2 I believe this will solve the problem.

however for the doubters out there, 2 things, even on a 1993 van there will be a relay that only allows power to the van battery, once the engine is running, this will be done either by sensing the power from the fridge wire or by a 3 way switch panel or internally inside the charge unit, that is why this wire can be perminantly live, and is so in all wiring after 1998.
you do not have to have both feed wires to the caravan [fridge and charge circuit] switched at the tow vehicle.
[only the fridge] if you switch the power wire at the tow vehicle as suggested by Bill you effectively make the internal van wiring redundant, this will throw up problems by its self for instance because if the power wire is switched there is no live wire to the van to run the lights pump ect while hitched to the car but with the engine stood as there is nothing to power them,

how many posts have there been with the question why have I no internal power in the van with the plug connected,
well they probably have a switched power wire from the tow car.

finally if there still is any doubt I suggest you refer to the vans handbook and schematics for a definitive answer the wiring of caravans has been evolving since the days of a single strip light powered by the blue aux wire in the 12N plug some caravan manufactures were quicker than others to up date their vans,
I will now retire, you have the information do with it as you will.

 

[Gafferbill]

sgtangel...........hello.

You can see Colin and I disagree on the solution to your problem.

I agree you should not alter the wiring on your tow car or utilise the ignition switched supply for battery charging.
My sole reason for taking part in this topic was because I believe wrong information was being given and that view has not changed.

I will just point you in the direction of this website which is the best explanation of all the different wiring systems.

Good luck with solving the problem.

 

[ProfJohnL]

I have deliberately not commented on this thread until now.

This is a classic example of how a forum is not the best way to resolve such issues, and the reasons is there are far too many unknowns, and having no contact with the actual components, the best we can do is speculate. this is akin to the "Blind leading the blind"

This is a 1993 caravan, and we know the standard wiring has changed since then. Perhaps a previous owner has attempted to modify the wiring and failed to do it properly?

We don't know if the OP has accurately described the symptoms.

If the matter were simple then the first steps the OP may have taken to resolve it would have worked. By all account it didn't, so the matter is no longer simple.

I would venture to suggest that if the car and caravan had been looked at by a competent techy, this matter would have been resolved within a couple of hours. Mainly because the techy could check all the systems in a way that would establish the wiring situation, and thus present an approved method of resolution.

Sometimes it is most expedient to admit defeat and let the professional do what they have trained for.

 

[colin-yorkshire]

I have deliberately not commented on this thread until now.

This is a classic example of how a forum is not the best way to resolve such issues, and the reasons is there are far too many unknowns, and having no contact with the actual components, the best we can do is speculate. this is akin to the "Blind leading the blind"

This is a 1993 caravan, and we know the standard wiring has changed since then. Perhaps a previous owner has attempted to modify the wiring and failed to do it properly?

We don't know if the OP has accurately described the symptoms.

If the matter were simple then the first steps the OP may have taken to resolve it would have worked. By all account it didn't, so the matter is no longer simple.

I would venture to suggest that if the car and caravan had been looked at by a competent techy, this matter would have been resolved within a couple of hours. Mainly because the techy could check all the systems in a way that would establish the wiring situation, and thus present an approved method of resolution.

Sometimes it is most expedient to admit defeat and let the professional do what they have trained for.

all right so I expected that bit at some time, if it has got to the position that a simple transfer of power in 12S plug warrants 2hrs at £50 an hour to sort out god help all you caravanners,

the OP wrote in the first post, "discovered that, whilst we are getting a constant 12v across pin 4 (green) which I think provides the power to the caravan for lights etc, and an ignition 12v across pin 6 (red), which powers the fridge ?? I am getting no feed, permanent or otherwise, to pin 2 (blue), which I think should be charging the battery when we are driving."

and "Can anyone advise if a 13pin socket on the car (assuming it has been wired correctly) connected via an off-the-shelf adapter, should provide a 12v feed to pin 2 on the 12S plug ?

so the OP has a good understanding of the problem and where the issue lies, if one needs professional help after that I am at a loss to explain any further, for a while now these subjects have amazed me just how unpractical some people appear to think caravans are,

moreover I can just imagine my fellow owners in the boat and motorbike fraternity laughing their socks off at the very thought of taking their pride and joy to a boat yard or dealer to fix the the simplist of issues.

I have had a long association with caravans but has now ended, this forum is the last bit of interest I had in the hobby. what is the point of having knowledge if it is not worth passing on, if the answer to just about every problem is take it to the dealer, my work is done,
good luck everyone and happy caravanning, at least with a boat you dont have to worry about flooding.

bye Colin,