What Is the Best Solution to Charge Two Starter Batteries and One House Battery?

Question:

Hi Jeff, I bought my boat a couple of months ago. The owner’s manual says that the battery charger only charges the two starting batteries - not the house battery on shore power. When I’m on my boat at the dock, should I have the battery selector switch on “All” so everything can charge? My refrigerator is 12v only. Aside from running a separate charger on my house battery, is there a practical way to keep it topped off? - Mitch

Answer:

Leaving the switch on "All" is a common way of charging all the battery banks from a single charger. A better solution may be to update the charger to one with 3 outputs and a higher charger rate.