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Wiring of 12S socket - confusion



 
 
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  #1 (permalink)  
Old June 26th 04, 04:15 PM posted to uk.rec.caravanning
Simon Hawthorne
external usenet poster
 
Posts: 137
Default Wiring of 12S socket - confusion

Hi all

Just bought a Smartcom dual relay and a 12S socket (pre-wired) - and
need to wire it up to my car. My van is a 2003 model - so there
should be no confusion (or so I thought).

The Smartcom instructions claim that it's connections use:
Pin 2 is Aux Battery (blue)
Pin 4 is perm live (green)
Pin 6 is fridge (red).

This, I think is the pre '98/99 wiring - so I should ignore.

So, to John Wickersham's Caravan Manual (printed in 2000).

That states that post '98 vans...
Pin 2 is spare
Pin 4 is Aux batt + live
Pin 6 is fridge
(this is different to the Smartcom instructions).

Another source of info
(http://www.caravanninglinks.co.uk/el...iring_code.htm)
claims....
Pin 2 - spare (but may be connected to pin 3)???
Pin 4 - power feed (plus battery charge)
Pin 6 - fridge

So, to summarise - I am confused. I know that pin 6 is for the
fridge.

Pin 1 - reverse (yellow)
Pin 2 - battery charging or spare?
Pin 3 - earth (or/and return for pin 4)
Pin 4 - either perm live or battery charge (via relay)??
Pin 5 - spare OR sensing device (?? - caravan manual)
Pin 6 - fridge
Pin 7 - Fridge earth

Can anyone put me right - nice and easily. I am not an auto
electrician and don't want to start blowing fuses.

I am confused about pins 2,3,4 and 5 - and how they fit my Smartcom
relay.

Thanks in advance

Simon
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  #2 (permalink)  
Old June 26th 04, 04:18 PM posted to uk.rec.caravanning
Simon Hawthorne
external usenet poster
 
Posts: 137
Default Wiring of 12S socket - confusion

Sorry to reply to my own post - but I also need to understand...

If the live feed is connected via the relay - am I correct in assuming
that if my caravan battery goes flat (over a week with no hook-up) -
if I connect the 12S socket to use the car battery - it won't work
without the engine running (because the relay won't let it)?

Thanks again

S.
  #3 (permalink)  
Old June 26th 04, 04:51 PM posted to uk.rec.caravanning
Tony Maris
external usenet poster
 
Posts: 161
Default Wiring of 12S socket - confusion

Hello Simon,


Wire the Smartcom exactly as it says on the unit. The one thing you need to
do extra is earth the black wire in the 12S socket to the car body,. along
with the white. Done this way, the Smartcom will work either old or new 12S
systems.

However, on post 1998 caravans, there is a problem with the centre pin
burning out. This is NOT a wiring fault, it is due to the change in
legislation (EN1648-1 Oct 1997). The cure for it is on my website at
http://www.towitall.co.uk/faq/faq1.htm but in short, you need to put a link
wire in the caravan plug, between pin 7 and pin 5, then while installing the
12S wiring on the vehicle, make an additional earth by using the brown wire
in the 12S. In other words, simply earth black, white and brown all
together, to a good earth point on the vehicle.

Whilst linking the 2 wires as described, I would also link pin 6 (fridge) to
pin 2 (spare) (again in the caravan plug). The result id that fridge now
has double the size of cable to power it and splits the load across 2 pins,
equally, it has double the earth also across 2 pins. It will be
significantly more efficient on 12 volts and you will never suffer pin burn
out.

Pin 4 in the 12S socket needs to remain permanent live. Its true that in
post 1998 caravans, the caravan battery is charged through this, but it is a
changeover relay in the caravan that changes the function of the pin. The
caravan battery will NOT be connected to the car battery until after the
engine is started. The changeover relay ensures this by sensing a voltage
on the fridge feed (which is voltage switched by the Smartcom). When there
is voltage to the fridge, the changeover relay is activated and switches off
the caravan interior lights and changes the power feed from no4 to the
battery charging mode.

The only thing I would say is, ensure that in wiring up the Smartcom, you
have a sufficiently heavy power feed to it Directly from the vehicle
battery. Existing feeds supplied by car manufacturers are almost always
inadequate. I test my installations with a 20 amp load applied and by
wiring direct using 6mm CSA cable (or twin 44/0.30 doubled up) I can
guarantee a voltage drop of less than 0.6 volts (to the output side of the
voltage sensing relay that I use) with a 20 amp load applied. Using
manufacturers feeds, we have recorded 3 volts drop and more. Bearing in
mind that a 12 volt fridge will not operate at less than 11.5 volts (at the
fridge), you can see the need for controlling the drop.

I hope this answers your question........

Regards

--
Tony M
Towbars & Trailers
Chesterfield
Specialists in Towing Equipment
NTTA Council Member
http://www.towitall.co.uk
QSA accredited for Towbars and Trailers



"Simon Hawthorne" wrote in message
...
Hi all

Just bought a Smartcom dual relay and a 12S socket (pre-wired) - and
need to wire it up to my car. My van is a 2003 model - so there
should be no confusion (or so I thought).

The Smartcom instructions claim that it's connections use:
Pin 2 is Aux Battery (blue)
Pin 4 is perm live (green)
Pin 6 is fridge (red).

This, I think is the pre '98/99 wiring - so I should ignore.

So, to John Wickersham's Caravan Manual (printed in 2000).

That states that post '98 vans...
Pin 2 is spare
Pin 4 is Aux batt + live
Pin 6 is fridge
(this is different to the Smartcom instructions).

Another source of info
(http://www.caravanninglinks.co.uk/el...iring_code.htm)
claims....
Pin 2 - spare (but may be connected to pin 3)???
Pin 4 - power feed (plus battery charge)
Pin 6 - fridge

So, to summarise - I am confused. I know that pin 6 is for the
fridge.

Pin 1 - reverse (yellow)
Pin 2 - battery charging or spare?
Pin 3 - earth (or/and return for pin 4)
Pin 4 - either perm live or battery charge (via relay)??
Pin 5 - spare OR sensing device (?? - caravan manual)
Pin 6 - fridge
Pin 7 - Fridge earth

Can anyone put me right - nice and easily. I am not an auto
electrician and don't want to start blowing fuses.

I am confused about pins 2,3,4 and 5 - and how they fit my Smartcom
relay.

Thanks in advance

Simon



  #4 (permalink)  
Old June 26th 04, 04:54 PM posted to uk.rec.caravanning
Tony Maris
external usenet poster
 
Posts: 161
Default Wiring of 12S socket - confusion

Simon,

further to my earlier post, under no circumstances should pin 2 be wired to
pin 3. Pin 2 was the voltage controlled feed for battery charging and pin 3
has always been an earth return. With some caravans connected to your car,
you would have a dead short.

Regards

--
Tony M
Towbars & Trailers
Chesterfield
Specialists in Towing Equipment
NTTA Council Member
http://www.towitall.co.uk
QSA accredited for Towbars and Trailers



"Simon Hawthorne" wrote in message
...
Hi all

Just bought a Smartcom dual relay and a 12S socket (pre-wired) - and
need to wire it up to my car. My van is a 2003 model - so there
should be no confusion (or so I thought).

The Smartcom instructions claim that it's connections use:
Pin 2 is Aux Battery (blue)
Pin 4 is perm live (green)
Pin 6 is fridge (red).

This, I think is the pre '98/99 wiring - so I should ignore.

So, to John Wickersham's Caravan Manual (printed in 2000).

That states that post '98 vans...
Pin 2 is spare
Pin 4 is Aux batt + live
Pin 6 is fridge
(this is different to the Smartcom instructions).

Another source of info
(http://www.caravanninglinks.co.uk/el...iring_code.htm)
claims....
Pin 2 - spare (but may be connected to pin 3)???
Pin 4 - power feed (plus battery charge)
Pin 6 - fridge

So, to summarise - I am confused. I know that pin 6 is for the
fridge.

Pin 1 - reverse (yellow)
Pin 2 - battery charging or spare?
Pin 3 - earth (or/and return for pin 4)
Pin 4 - either perm live or battery charge (via relay)??
Pin 5 - spare OR sensing device (?? - caravan manual)
Pin 6 - fridge
Pin 7 - Fridge earth

Can anyone put me right - nice and easily. I am not an auto
electrician and don't want to start blowing fuses.

I am confused about pins 2,3,4 and 5 - and how they fit my Smartcom
relay.

Thanks in advance

Simon



  #5 (permalink)  
Old June 26th 04, 05:00 PM posted to uk.rec.caravanning
Simon Hawthorne
external usenet poster
 
Posts: 137
Default Wiring of 12S socket - confusion

On Sat, 26 Jun 2004 17:54:56 +0100, "Tony Maris"
wrote:

Regards

--
Tony M
Towbars & Trailers
Chesterfield
Specialists in Towing Equipment
NTTA Council Member



Tony - thank you.

I've had a good look around your site - but even then I was unsure
even then after reading the bit about burning out 12S sockets.

I will print out your reply - and take it down to the car with me!

Next time I'm passing Chesterfield I'll call in and thank you!

Kind regards

Simon
  #6 (permalink)  
Old June 26th 04, 05:08 PM posted to uk.rec.caravanning
Simon Hawthorne
external usenet poster
 
Posts: 137
Default Wiring of 12S socket - confusion

On Sat, 26 Jun 2004 17:51:37 +0100, "Tony Maris"
wrote:

Whilst linking the 2 wires as described, I would also link pin 6 (fridge) to
pin 2 (spare) (again in the caravan plug). The result id that fridge now
has double the size of cable to power it and splits the load across 2 pins,
equally, it has double the earth also across 2 pins. It will be
significantly more efficient on 12 volts and you will never suffer pin burn
out.



Tony - sorry - a further question. If I link pins 2 and 6 - what do I
connect to the smartcom. Pin 6 is for the fridge connection - and pin
2 is for the Aux battery connection? If I join the two......?? Am I
missing something?

S.
  #7 (permalink)  
Old June 26th 04, 07:00 PM posted to uk.rec.caravanning
Tony Maris
external usenet poster
 
Posts: 161
Default Wiring of 12S socket - confusion



"Simon Hawthorne" wrote in message
...
On Sat, 26 Jun 2004 17:51:37 +0100, "Tony Maris"
wrote:

Whilst linking the 2 wires as described, I would also link pin 6 (fridge)

to
pin 2 (spare) (again in the caravan plug). The result id that fridge now
has double the size of cable to power it and splits the load across 2

pins,
equally, it has double the earth also across 2 pins. It will be
significantly more efficient on 12 volts and you will never suffer pin

burn
out.



Tony - sorry - a further question. If I link pins 2 and 6 - what do I
connect to the smartcom. Pin 6 is for the fridge connection - and pin
2 is for the Aux battery connection? If I join the two......?? Am I
missing something?

S.



Hi Simon,

yes, you are missing something. Forget what John Wickersham said, Whilst
strictly correct, it confuses the issue. Connect both the blue and the red
wire into their respective terminals in the Smartcom. On pre 98 vans the
blue would do battery charging, on post 98 vans, it does nothing. However,
that gives us an opportunity to use it. At the moment your set-up would
only use the red wire, and 1/2 the relay to power the fridge. By linking no
6 pin (red) to no 2 pin (IN THE 12S PLUG) we can also use the other 1/2 of
the relay, and the blue wire to power the fridge. This doubles up on the
cable thickness to the fridge supply and spreads it over 2 pins in the
plug/socket interface. This SIGNIFICANTLY reduces voltage drop in the 12S
cable, which is the biggest bottle neck of all.

By simply inserting the links in the caravan plug, tests done on my training
courses have shown improvements at the fridge of over 1.5 volts. This was
purely down to voltage drop in the 12S cable and plug/socket, as nothing
else was changed.

Regards

--
Tony M
Towbars & Trailers
Chesterfield
Specialists in Towing Equipment
NTTA Council Member
http://www.towitall.co.uk
QSA accredited for Towbars and Trailers



  #8 (permalink)  
Old June 26th 04, 10:53 PM posted to uk.rec.caravanning
bill lord
external usenet poster
 
Posts: 291
Default Wiring of 12S socket - confusion

On Sat, 26 Jun 2004 17:15:22 +0100, Simon Hawthorne
wrote:


Can anyone put me right - nice and easily. I am not an auto
electrician and don't want to start blowing fuses.


Goto Tony Maris's site the information is spot on

http://www.towitall.co.uk/default.htm


(remove the spam to reply)
I don't suffer from stress..................I'm just a carrier
  #9 (permalink)  
Old June 26th 04, 10:53 PM posted to uk.rec.caravanning
bill lord
external usenet poster
 
Posts: 291
Default Wiring of 12S socket - confusion

On Sat, 26 Jun 2004 17:18:06 +0100, Simon Hawthorne
wrote:

If the live feed is connected via the relay - am I correct in assuming
that if my caravan battery goes flat (over a week with no hook-up) -
if I connect the 12S socket to use the car battery - it won't work
without the engine running (because the relay won't let it)?


No it will work but your caravan battery will not be in the circuit so
will not try to drain your car battery, though if you try to do too
much with the car battery it may go flat. I use my car battery as very
much an emergencies only source of power.


(remove the spam to reply)
I don't suffer from stress..................I'm just a carrier
  #10 (permalink)  
Old June 27th 04, 03:19 PM posted to uk.rec.caravanning
Simon Hawthorne
external usenet poster
 
Posts: 137
Default Wiring of 12S socket - confusion

On Sat, 26 Jun 2004 17:54:56 +0100, "Tony Maris"
wrote:


Regards

--
Tony M
Towbars & Trailers
Chesterfield
Specialists in Towing Equipment
NTTA Council Member
http://www.towitall.co.uk
QSA accredited for Towbars and Trailers



Thanks Tony. Job done this PM. Not sure where you normally site the
relay - but I decided to hide it in a corner under the chassis near
the rear wheel (I have a SWB Pajero). I wish now (having finished it)
that I'd have sited it under the bonnet - and then run three cables
from the realy to the back. Might have to do it again next weekend!

Anyway, thanks - it all works... and I did the linking of the pins in
the caravan plug.

Kind regards

Simon

 



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