Factory options for second battery charging?

[rod_vw]

We’re maybe ordering a new bespoke LWB Auto Crafter or TGE to replace our current one. I am researching the factory options for second battery charging WITHOUT factory fitment of a lead acid second battery. The Volkswagen Body builder guidelines document talks about various options including lithium charging and maybe a second alternator. I am aware that a Grand California and some of the Knaus campers built on the Crafter / TGE chassis have a switch on the dash for what I believe is enhanced charging,
Has anyone got knowledge of these for use in our world of camper building? If so the relevant PR (option) codes would be helpful.

 

[Poleman]

Our 2025 TGE has the factory second AGM Battery located in the engine bay. The converters of my van removed the battery, sensor and positive terminal from the engine bay split charger when they upgraded my van to lithium. The van has been in for a manufacturer update for the batteries and it cannot complete because the battery is not detected. The dealer even refitted the battery and removed parts and disconnected the Lithium battery. Still won't update, so they suggested completely disconnecting anything to do with the conversion and trying again. It's waiting to go in for the converters to try this. I think in future fitting a second battery ex works would be the better option with the new infotainment system fitted which reportedly is causing many issues with conversions on the new models.