Wiring multiple batteries together in a series wiring arrangement as shown below creates a battery pack with a Voltage that is the sum of all the batteries Voltages in the pack added together. For example two 12 Volt batteries wired in series creates a 24 Volt battery pack, three 12 Volt batteries wired in series creates a 36 Volt battery pack, and four 12 Volt batteries wired in series creates a 48 Volt battery pack.