The battery can be as simple as a 12 volt battery of moderate size, much like a car battery. The capacity, or the energy storage capacity, of the battery is directly related to its physical size. The larger the battery, the higher the capacity. A 7 Ampere Hour (AH) battery might be the size of an envelope box where as a 220 AH battery would be larger than a car battery. The battery bank is made up of several batteries connected together in series and parallel combinations to develop the voltage and current capacities needed for a particular system. Two 12 v batteries connected in series make up a 24 volt battery. This battery would have the same current capacity of either of the two batteries individually. If the 12 volt battery were to be rated for 12 v at 220 AH, then the series connected battery combination would be rated at 24 volts at 220 Ampere Hours. If we carry this out further, making a 48 volt battery by connecting the original two batteries in series with two more batteries in series (a total of 4 batteries) we make one 48 volt battery with a capacity rating of 220 AH. Once the battery voltage is satisfied, by connecting batteries in series, we then consider the total battery Ampere Hour capacity needed. To meet this requirement we connect the 4 series connected batteries in parallel with 4 more series connected batteries, making a 48 volt battery with 440 AH capacity. The process continues until the battery is sized to meet the load demand.
CAUTION – Even a single cell battery at modest AH ratings has the ability to supply very high currents for short durations. Shorting the terminals of a battery will cause maximum current to flow, and the power will be dissipated in the load. Resistance is the limiting factor in the power transfer process. Without resistance, as in the case of a short circuit, maximum current flows for the duration of the batteries ability to contain the power developed during energy transfer process. This is limited by the physical construction of the battery and the duration of the short circuit. The battery can, and most likely will explode causing the contents of the battery, to be sent in all directions. This is a very serious mishap often resulting in major physical injury or death.
