All power supplies offer hold up or buffer time that is provided by the electrolytic capacitors utilized in the power supply design. Power supplies typically provide 15 to 40 milliseconds (ms) of hold up time in the event of a power loss; however, many applications require additional backup time. The timeline shown here compares the maximum amount of backup time for a 24V, 10A load for the three methods of providing backup power – buffer modules with capacitor-based energy storage, DC-UPS systems with super-cap based energy storage, and DC-UPS systems utilizing lead acid batteries to store energy. The backup time shown for each DC-UPS controller is based on the largest battery size allowed by each DC-UPS controller.