A power supply is a device that stores and generates electricity through a chemical reaction brought upon by the unique mixture of chemicals and gases contained within. When activated the power supply converts the chemical energy into electricity, which is then channeled through the focusing crystal. The electricity is then concentrated into a beam which, when moving through the cycling field energizers, causes enough ionization in the surrounding molecules to create a constant, controlled beam of plasma. Excess energy is then channeled back into the power supply, resulting in energy being lost only when the energy blade comes into contact with other forms of energy or dense material. The specific properties and color of the plasma is mostly dictated by the unique composition of the focusing crystal, but the power supply also contributes to these properties.

Contrary to popular belief, any type of power cell is capable of being used as a power supply. As long as the chosen power supply is integrated properly, the lightsaber will function correctly. While newer versions of the power cell are more efficient, many sentient beings still prefer to use diatium power cells as their power supply. The reason for this preference is partly due to tradition and partly because diatium power cells are capable of recharging their energy stores naturally over time. This factor combined with the low energy usage of the lightsaber allows the diatium power cell to last almost indefinitely; therefore becoming accepted as the most ideal power supply.