An electrical circuit can include a power supply that provides primary power, and an electrical load coupled to the power supply. The electrical circuit can also include an energy storage unit coupled to the power supply and the electrical load. The energy storage unit can include at least one energy storage device that stores reserve power using the primary power, and a first switch disposed between the power supply and the at least one energy storage device. The energy storage unit can also include a controller that operates the first switch from a closed position to an open position after a first amount of time. The at least one energy storage device can receive the primary power when the first switch is in the closed position. The at least one energy storage device can fail to receive the primary power when the first switch is in the open position.