text: If a second AC power outage occurs before the batteries have completed charging, the 
  system starts in service state and does not permit I/O operations to be restarted until the 
  batteries are half charged, which provides enough capacity to perform a clean system shut 
  down in case of another power loss. The recharging process takes approximately 30 minutes. 
  
  The system automatically schedules maintenance battery discharge cycles to extend the 
  lifetime of the batteries and ensure that the system can accurately measure the charge in the 
  batteries. Discharge cycles ensure that the batteries have sufficient charge to protect the 
  Storwize V7000 system. For more information about maintenance discharge cycles, see this 
  IBM Knowledge Center web page. 
  
  To shut down your Storwize V7000 system, complete the following steps: 
  
  1. Ensure that no hosts are using the storage system, and that you stopped all FlashCopy 
  mappings, remote copy relationships, data migration operations, and forced deletions. 
  In the GUI, click**Monitoring**→**System**. Then, click**System Actions**and choose**Power**
  **off System**, as shown in Figure 4-43. 
  2. 