This message is posted when the Battery Backup Unit starts a battery test. The test estimates the battery capacity in hours, which is how long the Battery Backup Unit can back up the 3ware RAID controller. This test performs a full battery charge/discharge/re-charge cycle and may take up to 20 hours to complete. During this test the Battery Backup Unit cannot backup the 3ware RAID controller; all units have their write cache disabled until the test completes.