Thanks to many who have answered, I now understand that an isolator prevents a discharged bank from sucking voltage from a charged bank, but at a voltage cost. Not good. A combiner does the same thing, without the voltage loss. Comes now the ACR, which is billed as "dual sensing". It appears to be a technological advance over the combiner, but I'm not entirely sure how so. Following the very much appreciated help from the forum, I wired the alternator directly to the house bank and removed the isolator. So is there a cost/benefit to using an ACR in the system to distribute the charge from my Freedom 20 inverter/charger?