Considered low-voltage batteries, 12-volt and 6-volt batteries are similar in basic construction; they are both categorized as lead-acid batteries. However, they differ in number of cells, amp-hour capacity and sizes.
The voltage of individual batteries is dependent upon the total number of battery cells in each unit. Determining the number of cells is simple, as each cell represents two volts each. Therefore, a 12-volt battery has six battery cells while a 6-volt battery has three cells.
Amp-hour capacity concerns the battery’s ability to measure the amount of functional energy — the higher the voltage, the greater the amp-hour capacity and total watt-hours. The 6-volt batteries have an amp-hour capacity of 100, equaling a total of 1200 watt-hours. The 12-volt batteries have an amp-hour capacity of 200 with 2,400 watt-hours.
The 6-volt batteries, individually used for small applications, do not vary as widely in dimension as 12-volt batteries, which are commonly used in automotive and marine-related applications. The 6-volt batteries are generally approximately 10 inches in length, 7 inches in width and 11 to 17 inches in height. The 12-volt batteries vary in size from approximately 8 inches in length, 7 inches in width and 9 inches in height up to 20 inches in length, 11 inches in width and 10 inches in height.