I have a API 20025 alternator installed on my yanmar 2gm20f which has three batteries, one starter for the engine, one operations and one starter for windlass and head. I keep my batteries charged using a battery charger while at the dock so the alternator is only used to maintain the batteries while i'm out on the water enjoying the boat. No solar panels or wind generators. What are my alternatives to changing this model or do I just get the same one? I am leaning towards a simple Napa alternator which half the amps but can do the trick. Just noticed that the connectors are a bit different. Any thoughts are welcome.