Isaac - Thanks for the feedback. You've convinced me to go with a stand alone MPPT controller. Do you have a smart alternator and if so how did you run the wire that lets the charger know the vehicle is turned on?
I'm building the basic 400 watt system that will have three 100 AH SOK lithium batteries. I watched the Long Long Honeymoon solar install video where they installed a stand alone Renogy DC to DC charger and a separate Victron MPPT controller. I'm looking at the suggested MPPT controllers you...