Batteries in the aft lockers
Michael,For the last year, I had a large "starting and deep cycle" battery in the aft starboard locker" and two six-volt 220AH golf cart batteries in series in the aft port locker. I did not install a separate vent. These are all flodded batteries (gel batteries don't gas, but flooded batteries will during high charging rates or when conducting an equalizing charge). I have a 20 amp multi-stage, multi-bank battery charger. The only time I worry about gassing is when I do an equalizing charge. This I do about every other month depending on how many battery cycles the batteries have been through. I have a Link 10 battery monitor that provides a great deal of information about the condition of the batteries. I use the equalizing charge to prevent the batteries from aging prematurely and to achieve maximum possible charge. I selected golf cart batteries because they are relatively inexpensive and take a lot of abuse in being discharged. I have an inverter on board to power a microwave, TV, and hope to add a refrigerator soon - that's the reason for all the battery capacity.Whenever equalizing, I remain on board and open both doors in the aft locker. I also have a fan blowing in the direction of the lockers during this special charging.When the boat is left in the slip, I usually leave the aft locker doors open as well, not because I am worried about gassing, but to dry out the aft locker area where, until recently, I had some water leakage when heeling. I don't leave the charger on in the slip unless the batteries are not fully charged. I usually have charged them before returning from sailing either through the outboard's 10 amp alternator or by running my 1000 watt quiet generator for a few hours.I am in the process of removing the golf cart batteries from the aft locker. Hunter has told me that I have too much weight aft (the golfs are about 70 pounds each). I am still trying to decide where to put them. My problem is that they are tall batteries, about 12 inches high. That is too high to fit under the cabin bench seats. I am leaning towards putting them under the sink in the head, but haven't made a final decision yet. If I place them under the sink, I will probably place a small vent between the forward end of the undersink area and the cabin teak wall because this is a much more confined space than the aft locker.I hope my ramblings contain some useful information for you.