so on my way back to dock the other day I got a low battery warning. I started the motor and continued on assuming this would charge my batteries. I had the motor running for a few hours. when I got back to dock I noticed the batteries did not seem to have taken any charge. I plugged the boat in to shore power and have turned on the charger. I have not been back to the boat so do not know if they have charged am going later today. I am assuming if the batteries have charged the alternator or the voltage regulator from the alternator has gone bad. if the batteries are not charged I assume I have a loose wire somewhere or the batteries them selves are bad or need fluid. beyond this I am not sure of what it could be. I have a 1991 hunter 30 with a yanmar engine. any other input of what I might check beyond this would be appreciated.