It seems like a lot of people are running two batteries. One for the stereo and one for starting the boat. I have bought a new starting battery and plan on using the current battery for the radio.

Question 1: Do you wire them in parallel or series? Seems to me it would be in parrallel to get more amp hours out but not for sure.

Question 2: I also bought one of the switches that allows you to use battery 1 or battery 2 or both batteries. It seems like a good idea but there is really no good place to mount it for easy access. Do I need this? If I do have this and lets say I have the starting battery at position 1 and the radio battery on position 2. I want to start the boat so I have the switch on position 1. Does that mean I can't have the radio on? Or does that just mean the radio battery wont get charged? And vise versa. If I have the switch on position 2 I won't be able to start the boat or the starting battery just won't get charged? I can leave the switch in the position where both are being accessed and everything works but then what is that really doing for me? I assume both batteries would get drained if I am listening to the radio but then they would both get charged too. But that is no different than if I just wired them up in Parallel.

Any suggestions?