Power shelf for computer servers

A power supply circuit comprising:

• an AC-to-DC circuit configured to convert an alternating current (AC) phase from multi-phase AC inputs to a direct current (DC) at a shared voltage node;
• a DC interface to connect with a backup battery unit (BBU);
• an asymmetric conductance component having a terminal electrically coupled to the shared voltage node;
• a step-up converter electrically coupled, in series, between the DC interface and the asymmetric conductance component;
• a bulk capacitor electrically coupled between the shared voltage node and an electric ground to hold power for at least one cycle of the AC phase;
• and
• a first DC-DC converter configured to draw power from the shared voltage node to supply power to load in an IT equipment rack.

A method of performing a battery test in a power shelf, comprising:

• providing a DC voltage through a DC bus coupled in parallel to power supply units (PSUs) in the power shelf, each PSU paired with a corresponding backup battery unit (BBU), wherein the power shelf includes at least a redundant pair of PSU and BBU, such that voltage and power is supplied through the DC bus sufficient to power rack-mounted equipment even when one of the multiple pairs is inoperative and wherein each PSU includes a power circuit configured to rectify an AC phase from an external multi-phase AC power source or draw power from the corresponding BBU when the PSU fails to provide power and voltage sufficient to power the rack-mounted equipment;
• generating a first schedule for a first BBU in the power shelf to perform periodic battery tests;
• when the first schedule indicates a first battery test, directing, via a controller, a step up converter coupled to the first BBU to draw power at a constant current to feed the DC bus, wherein the step up converter is in the power circuit of the PSU corresponding to the first BBU;
• and
• monitoring the first BBU via the controller for potential failure or defect.