Current is the rate of flow of electrons per unit time and is measured in amperes (A). A coulomb (C) is the quantity of electricity conveyed in one second by a current of one ampere.

Resistance is opposition to the flow of current. As resistance increases, current decreases as resistance and current are inversely proportional.

Voltage (V) is the electrical potential difference between two points. Electrons will flow as current from areas of high potential (concentration of electrons) to areas of low potential. Voltage and current are directly proportional in that the higher the voltage applied to a conductor the higher the current that will result.

Connecting the 8 batteries in series multiplies their voltage while keeping their current the same yielding a 120V 25A configuration. Connecting the 8 batteries in parallel multiplies their current while keeping their voltage the same yieleding a 15V 200A configuration. Using a series-parallel connection, 4 batteries can be connected in series and 4 can be connected in parallel resulting in a 60V 100A configuration.

Direct current flows in only one direction in a circuit, from the negative terminal of the voltage source to the positive. A common source of direct current (DC) is a battery.