Quote Originally Posted by jmb View Post
I was told that an alternator is designed to keep a charged battery charged. They are not designed to charge a dead battery.
This is for the most part, correct. Alternators do make for a poor battery charger. if a house bank is deeply drawn down while at anchor, its best to rely on shore charging to replenish the battery. The engine would have to run at above idle speed for a number of hours with no loads, in order to recharge the battery.