aux to lithium

[lvdbroek]

Hi there, recently bought a 2020 VW T6.1 multivan (L2 - 4 motion) which is now being converted. There is a factory installed auxiliary battery beneath the driver seat that probably powers the factory installed diesel heater. I want to install a Victron DCDC and 270AH Koven LiFePo4 battery. My initial thinking was to replace the aux AGM battery with the Koven lithium battery, install an Inverter beneath the passenger seat and MPPT, 230V->12V charger all in the back of a kitchen unit. But, the shop that is doing the conversion tells me that the aux battery underneath the driver side is specifically programmed in the onboard VW computer and should not be removed as it would give all sort of onboard issues. They have not done this before and their suggestion was to leave the aux battery in place, stick the Lithium battery underneath the passenger seat, run a cable from the starter battery via a DCDC converter to charge the lithium one. This seems overkill to me plus now my plan to put the inverter below one of the seats doesn't work anymore. Anybody out there who has done this and would be able to share their experiences? Many thanks