I’m wondering if it’s possible to charge my caravan’s battery by using a 7-pin to 13-pin trailer adapter followed by a 13-pin to 7-pin splitter. Is this setup capable of charging the leisure battery in my caravan, and are there any specific considerations or wiring requirements I should be aware of when using these adapters for this purpose?
Additionally, if anyone can shed some light on why it’s challenging to find 7-pin to 7-pin caravan Y-split cables, that would be greatly appreciated. Thanks in advance for any advice and insights!
If you’re asking whether it’s possible to use a 7-pin socket on a vehicle to operate the battery circuit on the caravan: no. This is known as a 12N socket, and has no power line and only runs the vehicle lights. This is why the 12S socket was introduced, back in the day; the twin 7 pin system is very much a legacy arrangement, 13 pin being the current standard. (I’ve just come across a US site which says that they have power on their 7 pin sockets. Another country, they do things differently there!)
It looks as if you’re going to need a charging relay on the car, that only operates when the engine is running. This is known as a switched circuit, and is there to prevent a discharged caravan batttery exhausting the car battery while stationary. There will also be an unswitched circuit, and a reversing light pin. This will then need to be attached on the car to either a 12S socket, or a 13 pin socket using an adapter.
If you’re planning on using pitches with hookups, so long as the caravan battery and onboard charger are in good condition, you’ll get a better charge that way. Hope this helps.
To work it out and put it into simple terms, the onboard battery charger operates via 240 volt mains electricity only. The electrical circuit in a vehicle functions by 12 volt power so a totally different circuit altogether.
On modern caravans after 1998 a habitation relay is fitted to the caravan.
This operates in 2 ways depending on whether the engine is running or not.
Engine running, internal 12 volt electrics in caravan all isolated except battery charging and fridge operation on 12 volt.
Engine not running, internal 12 volt electrics in caravan all operate from the car battery and fridge will not operate on 12 volt.
In practice, the charging of the caravan battery from the car is not overly effective. It is a long way from the cars alternator at the front of the car to the caravan battery so there is a lot of volt drop in the cables.
Also, some modern cars now do not fully charge the car battery, leaving some room for regenerative braking to recover energy. This will reduce the charging voltage after a relatively short time meaning the caravan battery will not be charging.
Most cars now have power saving systems which switch off electric consuming equipment in the car after half an hour or so to stop the battery becoming discharged. You may notice the radio stops working after awhile due to this system.
However, on my 2017 Seat Ateca with factory fit towbar, the smart alternator is made "dumb" when a trailer is connected. It gives out a constant 14Vdc.
No help to the original poster's requirement though!
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Topic: Charging Caravan Battery with Adapter
via mobile 01/11/2023 at 10:36pm
