The thread about the direct vent heaters got me thinking how nice it would be to have a heater on the boat. So I did a little research and ended up calling the Espar dealer in Seattle. In our conversation about the heater and installation he told me that all outboard motors don't have large enough alternators to charge the boats battery system. Even though the outboard manufactures claim x amount of output, the actual output is much less and eventually if you don't charge your batteries from an outside source they will go dead. He said they helped an Alaska Fish and Game boat that was having issues with their navigation electronics going out and when it was all said and done the problem was the twin outboards on the boat were not putting out enough charge to keep the batteries full and the heater was drawing the batteries dead. They fixed the problem by installing a house battery and another type of charger that has slipped my mind. I'm new to boat mechanics but does this sound right? I ran my boat all summer long and never charged the batteries by an outside source and when I brought them in for the winter they took very little charge. What do you guys think? Spoiled One did GC do anything special to your boat for your Espar installation?