The batteries in the datacenter are simply there to hold the power until the generators are all up and running, and the phases are in sync. They create 3 separ

The batteries in the datacenter are simply there to hold the power until the generators are all up and running, and the phases are in sync. They create 3 separate arrays of batteries in each back. Each array represents a power phase, A-B-C.. if I remember correctly, each array has a number of low voltage/2000 amp batteries connected in series to make up for a 2000amp 480 volt leg on the other end. In a tier 4 plus+1 datacenter, they have 4 battery rooms and 4 generators for each data pod. You have a primary generator and UPS battery set, and a backup generator set for each pod. And then that generator set has its own primary and secondary backup set. The end result is that they can work on any piece of equipment without interrupting power. In the event they lost the primary set or needed to take it offline for maintenance, they have the whole secondary redundant set to fallback on. The servers on the received on the power cord after it passes the switchgear never know that there has been power source changes on the other end.