I watched a prog about Tesla cars last year. It showed building the cars. If my memory is correct they used a battery pack made of a lot of small batteries connected in a combination of series/parallel.
It's no different with any battery make up, they are made of cells - the highest voltage is around 3.7v from a LiPo cell.
Your old lead acid car battery is 6x 2 v cells.
Submarine batteries are no different, lots of cells
