13 pin battery charging

[Jasmon]

Hi how’s it goin? I have a 2022 transporter with a factory fitted towbar- I’m looking to charge a leisure battery in a trailer which I plan to tow with the van. Does anybody know if the ignition switched 12v wire in the 13pin trailer connection will have all the relays needed to charge the leisure battery correctly or do I need a split charge setup?
Jason

 

[n10n]

Hi,

The ignition switched feed to the trailer socket is only 2.5mm2 wire. This basically means you can't put significant currents through it without risking burned fuse or worse, melting wires. Now, consider if you were to just connect the leisure battery in the trailer directly. Then one day, your leisure battery is empty but starter battery is full and you turn ignition on. There's nothing to limit the currents so a huge current rush will go through the wire.

Imho you can't really do it safely/reliably without having a DC-DC charger in between to limit the current. In this case it would also have to be quite modest one because of the thin wiring.

 

[Jasmon]

I was wondering what size the wire was,yes I can see that it’s far too small. I have also been looking at using the ctek d250se as a charge controller ,but over the this length the cable needs to be at least 6mm2- looks like some new wiring needed to achieve this,thanks

 

[roadtripper]

You may be better off fitting an Anderson connector to the battery and arranging a way to charge it in the van as you drive.

Getting significant charging currents from the alternator at the front back to the trailer, especially if you want to connect through the 13 pin socket, is going to be tricky.

Have a look at @Dellmassive power box projects.

If you want to look at modest DC-DC Sterling now produce a downrated one designed to help charge lithium power pack type systems that runs at 10A (and can be downrated further by a remote) which if your power needs are modest may be an option.

 

[Jasmon]

You may be better off fitting an Anderson connector to the battery and arranging a way to charge it in the van as you drive.

Getting significant charging currents from the alternator at the front back to the trailer, especially if you want to connect through the 13 pin socket, is going to be tricky.

Have a look at @Dellmassive power box projects.

If you want to look at modest DC-DC Sterling now produce a downrated one designed to help charge lithium power pack type systems that runs at 10A (and can be downrated further by a remote) which if your power needs are modest may be an option.

Thanks for that- the power box projects look interesting- lithium power bank may be the way to go for this-it would come in handy when not using the trailer also-I would have to tailor my power usage to suit

 

[Dellmassive]

Renogy show that for trailer and caravan battery charging, a dc-dc charger should be placed in the caravan/trailer.

The tailor sockets normally have a 30A fuse, but will volt drop you night only have 10A to play with.

Either way.

A dc-dc can be fitted in the trailer, with associated 12v battery, and charged with the trailer socket when driving.

A charger with adjustable settings would be preferable.... But even the normal chargers will work.

They normally try to ramp up to full current, but then detect the volt drop over the run, so scale back with the charge power.... 8-10A may be possible.... But I've not tested it.

 

[Jasmon]

Thanks for the info - Renogy are a new one on me-will have a look at their stuff