13pin Towbar Electrics - charging leisure battery!

[MKC]

Hi All,

I’ve just had a towbar fitted to my T6 and during the fitment I had a lengthy conversation with the fitter about leisure battery charging. He was fully NTTA approved so I would say qualified.
I mentioned the need for a DC2DC charger on the EU6 ‘Smart Alternator’ vehicles, but he said non of towbar Specific electrical wiring systems incorporate this for charging leisure battery on the towed vehicle (caravan or trailer tent). They still only utilise an ignition relay or VSR.
Surely, charging a leisure battery inside the T6 should be no different from charging one on a towed unit? I have read the very informative post on DC2DC systems, but just find it strange how Westfalia and Right Connections, to name 2 companies still use the ‘old system’

 

[mmi]

Or possibly we are outsmarted by VW and the others - by changing charging regime to "old fashioned one" when trailer is connected.

A while ago requested the trailer users to keep eye on this - unfortunately no replies to confirm or overrule the above.

Trailer/Caravan Charging from a T6 (Help requested – Voltage Measurements When Towing)

Help – voltage measurements when towing a trailer/caravan requested. When towing, what’s the voltage at your cigarette lighter socket (in the lower one in the dash)? No fancy instruments are needed, just any gadget will do. The following background data is appreciated: 1)...

www.t6forum.com

 

[MKC]

Curious what charging system is utilised if a 2nd battery is fitted as optional extra on new van. I’ll look at charge voltage next time I have something in tow?

 

[catfood12]

There's a second two pin connector on the Westfalia loom to pin 9 of the socket, that's not connected with the standard loom/ecu, and stays loose under the passenger seat. Westfalia make an additional kit as below to power this via a relay from the starter battery. I just ran it to the second battery though.

 

[Phil_G]

Curious what charging system is utilised if a 2nd battery is fitted as optional extra on new van.

A relay

Surely, charging a leisure battery inside the T6 should be no different from charging one on a towed unit?

It isnt different VW themselves use a simple relay.

I have read the very informative post on DC2DC systems, but just find it strange how Westfalia and Right Connections, to name 2 companies still use the ‘old system’

Three companies. VW
A cheap, easy and effective improvement is to replace the standard relay with an ideal diode circuit. Then the aux battery cant feed back to the starter as Loz witnessed, its unidirectional so the aux battery can only receive current from the alternator, which it will whenever the starter voltage is higher than the aux voltage (an ID has no forward voltage drop). Its not as good as a B2B but costs a fraction and is a big improvement on the VW relay, negating the 'discharge ' problem and needing no 'ignition live' or VSR-style switching You could very easily incorporate one into a tow-bar aux charge feed.
Cheers
Phil