There are several possible configurations you can create when connecting batteries together. There are three things to keep in mind.
1. When connecting batteries in series, you will increase the voltage and the amp-hour capacity will remain the same.
2. When connecting in parallel, you will increase the amp-hour capacity and the voltage will remain the same.
3. To increase both numbers, connect multiple sets in series/parallel.
Connecting Batteries in Series - Picture 1 is the connection of two matched batteries used to double the voltage at the same amp-hour capacity, e,g, two 6 volt batteries to give 12 volts or two 12 volt batteries to give 24 volts. Picture 2 is the connection of four matched batteries to quadruple the voltage, e.g. 4 X 6V = 24V or 4 X 12V = 48V. Often used in golf car, sweeper / scrubber machines, and smal EV and marine deep cycle applications. Also seen in large trucks, RV's, and buses for engine cranking applications.
Connecting Batteries in Parallel continued... Picture 4 is the connection of three matched batteries to triple the capacity at the same voltage. Used when eve more engine cranking or deep cycle capacity is needed at the same voltage beyond Picture 3. (Note: Fore engine cranking applications, cranking amps CCA, are multiplied by the number of parallel connections as with amp-hour capacity in deep cycle applications)
Connecting Batteries in Series / Parallel - Picture 5 is the connection of four matched batteries used to double both the voltage and the capacity. Often used in trucks, buses, marine, RV, Solar Energy Battery Back-up applications, and Wind energy back-up applications.
Connecting Batteries in Series / Parallel continued - Picture 6 is the connection of eight matched batteries to quadruple the voltage at double the capacity. Often used in larger golf cars, sweeper / scrubber machines, large electric vehicles, and solar energy battery back-up systems.