After all these years (5 Nautiques) I still don't quite understand this gauge. I plead ignorance. So, we here in the north sometimes in the Spring or Fall are forced to have the boat set for a week or two between sessions. So as not to be disappointed when I get to the lake, I will throw the charger on it. Do I need to do this? If I check the gauge, what should it read so it will start the boat?