A system may include a first capacitor, a first switched-mode power supply configured to deliver energy from a power source to the first capacitor at an output load of the first switched-mode power supply, a second capacitor having a capacitance larger than the first capacitor, a second switched-mode power supply configured to deliver energy from the power source or a second power source to the second capacitor and one or more switching elements coupled between the first capacitor and the second capacitor. The system may operate in a plurality of modes, including a first mode in which the first switched-mode power supply transfers energy to the first capacitor and the second capacitor, a second mode in which the second capacitor transfers energy to the first capacitor, and a third mode in which first switched-mode power supply transfers energy to the first capacitor and the second capacitor and the second switched-mode power supply transfers energy to the first capacitor and the second capacitor.