Hello,

We need your expertise and could do with some electronics insights as we are about to get the towbar installed:)

We found a Puck that meets our expectations. From the 90s but already upgraded to a 13 pins socket for the towbar. It has a leisure battery which is not connected to the 13 pins socket circuit (lets call it circuit - we actually dont have any glue as we have never ever dealt with these kind of things) but only charges via external charger.

What we would like to achieve:
- Car drives -> leisure battery charges
- Car drives -> fridge works using the energy coming from the connected towbar plug.

What we would like to know:
- What towbar to get? One with 13 pins as the Puck also has 13, correct?

- What else do we have to ask for: "please fully wire the 13 pins so we can charge the battery and fridge"? "Please also install relay XYZ because this is needed to properly run the intended setup"? Yes, we will also ask the towbar fitting company but today's phone call with one of them was rather disappointing as it was more of a sales pitch than knowledgeable guidance...so we stopped asking around and thought to consult with you first.

- What is the generic bypass relay that comes with the wiring kit? We understand this thing coordinates the car electronics vs. the Puck electronics voltages etc so everything runs smoothly, right?

- Does this bypass relay also coordinate stuff for the leisure battery charging and fridge? We understand that there also splitcharge relays that power the caravan's 12 volt supply, battery charging and fridge via the socket. But is this the same as the bypass relay but just another name for it?

- And what is a "voltage-sensing caravan combination relay"? We understand this is yet another relay that controls current from the towing vehicle to a towed caravan's auxiliary (fridge/battery) circuits. They are designed to stop the battery of a vehicle connected to a caravan from being discharged when the
vehicle's alternator is not charging. So is this something different to the other two relays?

- And this one is probably more difficult: currently, the leisure battery is not connecting to the 13 pins socket, it wont charge even if the car is properly setup as told by the seller. So, what exactly step by step is needed to make it work? We would obviously never intend to do this ourselves after looking into Complete new Electrical System in 1998 Familia but with your input we would ask around if someone with some kind of electrical work experience could assist us.

- And does it get easier if we just wanted the leisure battery to charge when connected to the ehu? What step by step is needed to make it work? A work around we see without doing any work is just using ehu, and connecting the battery charger to one of the power sockets inside the van and connect it to the battery. Or will this cause issues?

So, you can see we really dont have any clue whatsoever with electric stuff. Anyone with any experience who could guide us to the light ?

Thank you,

You also need to consider your car/towing vehicle. If it is fairly modern with "fancy" electrical systems, it is usually best to specify a dedicated wiring kit, which will provide all of the required connections to the socket and all of the relays etc. If your car is still under warranty, you definitely need a dedicated kit - preferably manufacturer supplied. You may also need to have the system re-programmed. When we did this on our volvo s40, I fitted the towbar and volvo electric kit / towing module (about £380) and had to have the programming done at Volvo for another £200. With our newer Ford Kuga, I struggled to get a dealer to even offer towbar fitting, but one put me in touch with a mobile fitter which they use. Ended up with a fixed towbar, dedicated electrics all programmed by the fitter for about £350 all in. The only difference is that the Kuga had non factory reversing sensors so no button to turn them off when reversing with the caravan. This isn't a major problem. In each case I went for a 13 pin socket.
You can get adaptors in either direction so doesn't really matter which you go for except that with 7 pin sockets you will need 2, one for the lights, the other for the power feeds. Usually one is black the 2nd grey. I think 13 pin sockets are neater and give a more reliable connection as they lock on, rather that just push fitting on the 7 pin ones.
There are loads of towbar fitting business around so you shouldn't have too much trouble finding one although I would avoid little one man bands without a good recommendation.

As for the caravan wiring, this gives a diagram of the wiring for 13 pin electrics.
https://www.google.com/search?q=13+pin+w...=9hlTfjirJlS6mM:

Pins 9 and 10 provide the power supply (for fridge) and battery charging. I would have thought that if you had 13 pin electrics these would exist but may not be connected to anything. If you have 7 pin on the caravan, they would be missing altogether and you would need a 2nd cable to provide the power and earth connections.

Given that you admit that you are not skilled in this area, I would suggest that if you are going for wiring alterations you leave it to a dealer (or a competent mobile fitter) as you can cause a lot of damage if you get it wrong. They will be able to sort you out.

regards

Steve

also.... is the fridge set up for 12v operation? If it is mains only then the problem is academic. You would usually have 3 way (mains, 12v, gas), Mains only, or maybe 12v compressor (unlikely given that you don't have any charging yet).

Good day Colin, Steve and Aaron. That was quick. The towbar will need to be ok for the Alko stabilizer. Colin the "full functionality" specification is really useful. Steve, your estimated cost seem really low. We were quoted 600 with a car specific wiring kit and our car is 10 years old and has no "fancy" electronics I guess. It was 200 less with a generic wiring kit. The fridge is, based on information from the seller, a 3 way fridge.

So, basically we will call the fitter, and ask to get a towbar with 13 pins, that is compatible with alko stabilizer and has full functionality wiring?

Power to the fridge and charging the battery en route is always an expensive part of an installation as they have to run two heavy duty cables from the front of the towing vehicle ( as that's where most automotive batteries are) to the tow bar. This entails lots of interior trim removal. Even a 10 year old car will probably have "can bus" electrics which will need re-coding. Newer cars with "smart alternators" are even more of a problem but hopefully a decent tow bar fitter will be aware of all these problems when quoting you.

If your caravan battery does not charge from the tow car then your caravan probably wasn't factory fitted with the required Schaudt Booster. Perhaps a simple leisure battery was retrofitted which is only charged from mains hook up?

All of these thing are fixable eventually.

Just had another read of your first post.
The split charge relays and voltage sensing relays are all about providing power from the car's electrical system to the 13 pin socket for transmission to the caravan's electrical system. If your caravan is not currently wired up for these functions then more work needs to be done in the caravan which will not normally done by the tow bar fitter.

A simple step for charging your battery on site is to purchase an ordinary automotive battery charger, plug it in to one of your 230Vac sockets and attach the charger's crocodile clips directly to the battery terminals (checking polarity of course)
Anything more permanent would require the services of a decent automotive electrician, mobile caravan technician or, last resort, caravan dealer.

Just checked through my records, and the cost to kit out my Kuga was £375 including the Brink fixed swan neck towbar, dedicated electrics and programming.
I had the work done at home by these people; http://www.jwtowbars.co.uk/ ; who are based in Nuneaton.

'Smart alternators' have been mentioned. With my 2015 Honda CR-V & 2013 Troll 540, operation of the fridge when towing was very hit & miss - until I read about smart alternators and their programming that decreases output when the car battery was fully charged - this means that on a journey of any length the alternator output was insufficient to run the Eriba's fridge. Solution? Press the button that disables the CR-V's 'auto stop' function! This stops the alternator backing-off its output and ensures plenty of wriggly volts to keep the fridge fully cooled! :)

Thanks Ray for your insight and explanations, this really helped us to understand the whole thing better. Keith, good to know regarding the start stop but we dont have that :) Steve, thanks again for looking up for how much and where.

We now have the towbar installed and used all of your input when ordering. For us, it was more expensive. We paid 450 for a swan neck, 13pins socket with the full functionality wiring, the relays and all of this. We were quoted 380 for the simple wiring, meaning no fridge/leisure battery charging.

Thanks again everyone!

I think you have done very well get the whole shooting match for £450, well done.

Research and asking questions nearly always brings the best deals in all sorts of situations.

One last tip if it's not too late?

If you have a black painted towball then that paint must be scraped or sanded off before attaching a caravan hitch with a built in stabiliser. If you don't, the paint will become ingrained in the friction pads of the stabiliser rendering it useless.

Good idea. A sturdy nylon chopping board is about that size ! I can always buy Debbie a new one if she notices it's missing.