While this picture shows the battery cells lined up port to starboard, this is not how they shipped from the factory. This entire battery compartment was re-configured to allow for a larger house bank of two group 31 12V batteries plus a group 27 starting battery. The factory installation had the batteries bow/stern, and only had room for two group 27's.
Unfortunately the physical height of this compartment would not allow for deep cycle golf cart type batteries so a compromise was made to use 12V "automotive cased" quasi-deep cycle batteries.