... the UPS Site wiring fault warning On-battery power-on function Smart RS232 communication interface ... Intelligent slot available Sealed lead-acid, maintenance free battery Technical SpecificationsProduct SeriesCASTLEModelBS1KBS2KBS3KRated PowerVA/W1kVA / 0.7kW2kVA / ... 4 ms from inverter to bypass and vice versaLED IndicatorsStatusLoad level / Battery level, Battery , Utility Power, Inverter, Bypass, ...