BBU · Battery Backup Unit
Rack-level battery that rides through power dips and absorbs sudden GPU load swings before the BESS or genset reacts.
Current numbers
~50% / 2–3%battery-capacity cut and double-conversion-loss cut from distributed BBU + supercaps vs central 2N
<2 msORV3 BBU ramp to full power on 48.5 V busbar droop; busbar held ≥46 V; PSU ≥97.5% (30–100% load)
<5 msrack BBU (OCP ORv3, 5+1 redundant) switchover — backup energy migrating down to the rack/silicon