FWIW, there is another option.....buy/use a 3-battery charger. We have a Pro-Mariner (West Marine) Pro-Nautic 50-3 to charge our 3-battery house system. The batteries (each "battery" is 2 Trogen T-105) are all connected to a (+) bus bar and a (-) bus bar with equal size & length cables; the house load is then connected to those bus bars. But the Batt chgr has 3 separate charge leads, one for each of the 3 batteries, and (supposedly) charges each "battery" as it needs. We've had this system for 7 years, the batts seem to do well on it, and we've never run out of power. We do run our genset daily (the admiral very much prefers cooking electric, and our refer and watermaker are both AC too-the refer needs to run at least 1/day to keep the boxes at temp. It seems to work well.