“Most DC-DC chargers draw a higher rate of amperage from the alternator than would be supplied if you let the alternator ‘push’ down the cable. This can be up to 40A or more per hour, quickly replenishing the house battery system.”
Hmmmmmm???
That is an odd quote you found there, because if you have an alternator running it’s charging the house battery.
The alternator could be charging at 80-100A but a dc-dc charger is typically 20-60 depending on what model you have. So the alternator can easily put more into the house battery than the dc-dc can take.
I think what that is trying to say is a dc-dc charger draws its boost current for longer and more consistently than an alternator.
Its true that some dc-dc chargers and VSR’s will ckeep charging until the house/starter battery reaches 12.6v after the engine has stopped. But the latest chargers like the one I used above also have a control wire that shuts it off as soon as the engine stops so your starter battery will not be plundered at all.
VW should really have upgraded the leisure electrics by replacing the relay with a DC-DC charging system when the T6 was designed.