That's funny! Back on our old boat when we were mostly daysailing off a mooring, I would just pick up "new" batteries each spring out of the boatyard junk pile. There were always boats throwing out batteries with life left in them (mostly gin palace power boats doing this) - at least one more season's worth for the type of sailing we did.

Ah, the good old days when batteries were free...You don't want to know what we just paid for T105's in Panama.

Mark