These isolaters will introduce a voltage drop between the charger and the batteries and as a result, the batteries will never fully charge. I have been a marine service technician specializing in electrical and electronic systems for 40 years. While it will not become an issue immediately, it will significantly reduce the life of your battery. No type of battery charger will overcome this issue. We no longer use isolaters in the marine industry, instead we install battery combiners or chargers that allow the charging of separate banks. For RV's, an excellent option is a 3 stage smart charger to the coach batteries with an echo charger connected from the coach batteries to the engine battery. Your start battery actually needs very little charging capabilities when the coach is sitting, just enough to keep it topped off. Hope this helps. Chuck
