[trit21]

My recommendation at this point is to try and look at the connections on the battery charger you can get to and see if 2 of the banks are connected. On my 12405, 40 amp not 60 as I stated above (my bad), there is a small screw on the cover that once removed you can slid the cover up to see the connections. My guess is that this one charger is charging both port and starboard battery banks. If 2 banks are connected with a thick wire, then that is most likely the case.