VOLTAGE REGULATION IN A DC UNINTERRUPTIBLE POWER SUPPLY

Disclosed is a system that includes a plurality of battery cells connected in series; a first connection path from an intermediate battery cell of the plurality to an output bus of the system; a second connection path from a last one of the plurality of battery cells to an output bus; a circuit switch installed along the second connection path, the circuit switch configured to open or close the second connection path; and an undervoltage relay in the output bus, wherein the undervoltage relay is set at a threshold voltage, and wherein the undervoltage relay is configured to control the circuit switch when a voltage on the output bus exceeds the threshold voltage or drops below the threshold voltage.