Put a 6 volt Optima in my 50 five years ago and haven't touched it. Sits all winter and fires right up in the spring. Never seen a charger or had the terminals cleaned. Another plus is it seems to not drain much at startup. Sometimes it takes a few cranks to start the old girl after sitting for a couple of weeks and the ammeter shows a slight charge for just a few seconds after startup before it drops back down in the normal range.
Bob
