The Battery Backup Unit (BBU) comes factory calibrated from the manufacture. When turning the BBU on it should be started in the following order:

 1-  Sense 2-  Charger 3-  Maintenance 4-  Output

The BBU provides DC power for Honeywell TDC 2000 in emergency situations when the default power unit may stop working. This switching on when the power goes down is automatic. When the power comes on again, the BBU will automatically switch off. A three amp fuse protects the ac line monitor, and a 50 amp circuit breaker protects the BBU output line.