I recently purchased a 2006 Mobious LS. It has the factor installed dual battery system (I don't believe it is aftermarket). I am not versed in these types of electrical systems, so please bear with me. It has a switch that allows you to either select 1, 2, 1+2 or off. The manual suggests that I should always set it to 1. However, in reading various forum posts, it seems some folks suggest that you should leave it on the 1+2 setting while cruising (therefore chargine both batteries) and set it on 1 while floating (which causes battery 1 - the starting battery - to be sensed and only run down to a certain level before being turned off).

Can someone please explain to me exactly how this system is designed to work and what settings I should use for various uses (cruising vs. floating vs. docking the boat)?

Of note, when I have it set to 1, it will not start. I have to have it set to 1+2 for the boat to start. I may be that starting battery is bad. Or it may be that I don't understand the system.

Thanks for your help!!