Hi,

I'm after some specific info and instruction on split charging & distribution.

We have a trailer & leisure battery and are used to running lights, fridge etc, off 12v DC when we camp. This year sees the addition of an EHU 3-way distribution block as we are going to France for two weeks.

Our tow car - a Zafira 2.0 dt - has twin electrics. What I'm after is guidance on using the secondary hookup to provide split charge duties to the leisure battery whilst in transit. This would be as a backup to the EHU and for those times when we opt for campsites without the EHU facility.

Additionally, it would be useful to allow supply of suitable charging duties in order to charge various items - ie: phones, MP3 players, etc.

What I had in mind was: (1) Secondary hookup to battery pack - 1 lead to supply charge to the leisure battery; (2) distribution from the leisure battery to - say - some for of bus bar or distribution rail; (3) Connections from the distribution rail to - say - cigarette type outputs to allow plugins.

I'm concerned about calculating loads and how to go about designing the circuit to cope. Obviously I will need to fuse protect the outputs, so I was thinking automotive type multi fuse holders.

Other concerns include, how to protect the vehicle main battery from charge depletion, suitable housings for the required wiring and getting the finished product tested to ensure safety of operation.

I would also like to incorporate some form of future proofing to allow charging of the leisure battery from alternate sources, ie: mains, wind-charging, solar panels, etc. We also have a 17' trailer sailor, so the latter option would give us double uses.

What do you think? Can anyone point me in the right direction?

Thanks

DM

EDIT: Something I forgot to mention; I've only a vague idea for what I want or am likely to need, so I'm open to suggestions too.

Try this

Tow bar electrical sockets.

Cars which are fitted for towing caravans will also be fitted with at least one, if not two electrical connection sockets attached to or adjacent to the tow ball. Commonly known as 12N and 12S sockets. Power from the vehicles indicators, fog lights and sidelights is transferred to the caravan lights of the same type through the 12N socket, whereas the supplemental power required by the caravans reversing lights, battery charger and fridge are sourced through the 12S socket. If you are fitting your own 12S socket you need to remember to fit a split charge relay to your car as well, this ensures that power to these high drain devices on your caravan only flows when the ignition is turned on. Should you not fit a relay of this type to your car and take a break during a long tow, you are likely to find that your car battery will not have enough power to start the engine when you resume your journey.

There are some important differences in the 12N and 12 S socket wiring in caravans manufactured up to 1998 and after 1999. The 12N connection has larger cables to help reduce voltage drop, however the pin allocation is identical to that of 1998. The 12S cable sizes for 1999 models have been increased to reduce voltage drop and improve load capacity. The car charge line (blue cable) is now left unused, the caravan battery is now charged via the green cable whilst the car engine is running, when the car is not running the green cable reverts to providing a power supply from the car battery, this action is produced from a relay fitted in the caravan. Also the fridge negative has been separated to reduce the loading on the system which unfortunately may cause compatibility issues with some older cars.

The 12N socket.

The socket is coloured black and houses 7 pins which are are numbered 1 to 7 and need to be connected using the correct grade wiring as follows (1998 Pin Allocation).:

Pin Cable Colour Function 1. Yellow Left turn signal 2.  Blue Fog light's 3. White Earth 4. Green Right turn signal 5. Brown Right hand side light 6. Red Brake lights 7. Black Left hand side light

The 12S socket

The socket is coloured grey and houses 7 pins which are are numbered 1 to 7 and need to be connected connected using the correct grade wiring as follows :

1998 Pin Allocation

Pin Cable Colour Function 1. Yellow Reversing light 2.  Blue Caravan Battery or charger 3. White Earth 4. Green Constant 12v feed 5. Brown Sensing device 6. Red Refrigerator 7. Black Spare

1999 Pin Allocation

Pin Cable Colour Function 1. Yellow Reversing light 2.  Blue Spare 3. White Negative for Lights & Charge 4. Green Interior Light & Charge 5. Brown Spare 6. Red Refrigerator 7. Black Negative for Fridge

Please note.
Make sure that when you wire the 12S socket you independently earth pins 3 & 7 to the car. ( if you don't it could well cause a bit of overheating).

13 pin continental system

  1.    Left side indicator
  2.    Rear fog lights
  3.    Negative for pins 1,2,4 & 8
  4.    Right side indicator
  5.    Right hand rear position & end outline, & registration plate
  6.    Brake Lights
  7.    Left hand rear position & end outline, & registration plate
  8.    Reverse light
  9.    Constant 12v power supply
10.    Power from ignition switch
11.    Negative for pin 10
12.    Coding for coupled trailer (on the plug pin 12 to be connected to pin 3)
13.    Negative for pin 9

You could plug in an spare plug into the tow socket and take a lead out that normally charges the leisure battery in your caravan to charge your off board leisure battery and a lead from the 12volt spare to run lights etc..  Or run wires from the rear of the tow socket back inside the car to charge your leisure battery on the move, i did this in my jeep. I just wired it up to a twin cigarette socket. It also keeps the 3way combicool fridge 12v side going on the move too. I wire up  two crocodile clips on the leisure battery going to a cigarette plug that plugs into my twin sockets

Chees Delta...

Quote: Originally posted by DebtMan on 20/7/2007

---

Hi,

I'm after some specific info and instruction on split charging & distribution.

We have a trailer & leisure battery and are used to running lights, fridge etc, off 12v DC when we camp. This year sees the addition of an EHU 3-way distribution block as we are going to France for two weeks.

Our tow car - a Zafira 2.0 dt - has twin electrics. What I'm after is guidance on using the secondary hookup to provide split charge duties to the leisure battery whilst in transit. This would be as a backup to the EHU and for those times when we opt for campsites without the EHU facility.

Additionally, it would be useful to allow supply of suitable charging duties in order to charge various items - ie: phones, MP3 players, etc.

What I had in mind was: (1) Secondary hookup to battery pack - 1 lead to supply charge to the leisure battery; (2) distribution from the leisure battery to - say - some for of bus bar or distribution rail; (3) Connections from the distribution rail to - say - cigarette type outputs to allow plugins.

I'm concerned about calculating loads and how to go about designing the circuit to cope. Obviously I will need to fuse protect the outputs, so I was thinking automotive type multi fuse holders.

Other concerns include, how to protect the vehicle main battery from charge depletion, suitable housings for the required wiring and getting the finished product tested to ensure safety of operation.

I would also like to incorporate some form of future proofing to allow charging of the leisure battery from alternate sources, ie: mains, wind-charging, solar panels, etc. We also have a 17' trailer sailor, so the latter option would give us double uses.

Post last edited on 20/07/2007 13:08:50

---

Have a look at http://www.sterling-power.com/ They can provide you with a fool proof split charge system. Buy a more powerful one than you need then you will be OK in the future.

Your biggest problem in a Zafira is where to put additional batteries. I have just had a look at the Mem's Zaf. and there does not appear to be a lot of room. My opinion, don't waste money on Leisure batteries; buy good quality traction batteries instead from some-one like Varta