Dave (and others),
Thanks for your knowledgeable replies, but now I have a new question. You say that it should take 12 to 18 hours to top off a single battery, but I get a reading of "full" after two to three hours of charging. I charge the batteries every week during the winter, either by taking the boat out, or by hooking up the charger. Does this mean that the batteries haven't drained that much and there really isn't that much charging to do, or is that "full" reading misleading?