Just a note...If you get to your boat regularly, perhaps live aboard (and can stand the hum), like to baby sit, etc., there isn't a better battery charger for your money than a ferro resonant. They are easily the most versatile chargers ever created...but NOT for AGM's. As an evolutionary product, AGM's have become very finely adapted to their working environment, but very finicky when it comes to their diet. You really do need to pay attention to their charging regimen..you'll need a programmable charge routine both on the alternator and shore charger sides. You'll be glad you did.