I see this is your first post so welcome to IRV2. There are a a lot of knowledgeable people who are willing to help you. Post often. I don't have 4 - 6 volt batteries but I believe each pair of batteries are wired in series to provide 12 volts. I believe the 2 pairs are then wired parallel to double the amperage available.
Don & Bev Morgan Weyauwega WI, 05 Itasca Horizon 40KD, 400 HP Cummins, Delorme GPS LT 40, Toad 07 Saturn Vue AWD, Air Force One, TST 510 TPMS, Mayor of Weyauwega 2007 - 2013, Waupaca Co Board Supervisor 2010 - 2014