Leisure batteries question

[roadtripper]

They may do it but it's against all good practice for long term battery health. VW don't do it and neither does any UPS manufacturer (nearer the day job).

If they have fitted a changeover switch or similar so one discharges before the other I've not seen such a system before and I'd question it's effectiveness trying to squeeze an extra 20ah capacity (about half a day run time) Vs the dead simple pair of 75ah approach.

It's very common not to charge the starter on EHU as generally if you are putting no load on them from the habitation side they don't need it. Folks that need it are in either off grid a lot or store the van for long periods and make alternative arrangements.

 

[Glenhyrst]

Folks that need it are in either off grid a lot or store the van for long periods and make alternative arrangements.

I guessed that to be the case but I cannot see any disadvantage to having all the on-board batteries charging on EHU. Just plug in one cable and job done.
I now have to provide a second charging source to the cab battery. Less frequent if the van often driven but a mild irritant if only used occasionally.

 

[roadtripper]

On the other hand as the vast majority of folks don't need it it's extra cost, extra space, extra wiring and something else to go wrong.

Those people that do want to do it tend to arrange for the charge to come from places other than EHU as it suits them off grid.

95% of Transporters on the road are not campers and are just fine without being plugged into the mains to charge their starters.

There are a ton of solutions though, just have a search around:

• Ad hoc internal maintenance charger plugged in 240v inside into 12v socket (though very recent from factory 6.1 don't seem to have the traditional gear lever one connected to the starter)
• Fit solar with twin outputs
• Fit a DC-DC charger that can reverse charge
• Fit something like the Ablemail AMT12 battery to battery trickle charger

I use a maintenance charger through the 13pin towing electrics to look after my single battery T6.1 as it sometimes sits idle. I didn't really need to but it was a fun thing to figure out and build.