The status of the UPS batteries. A batteryLow(3) value
indicates the UPS will be unable to sustain the current
load, and its services will be lost if power is not restored.
The amount of run time in reserve at the time of low battery
can be configured by the upsAdvConfigLowBatteryRunTime.
A batteryInFaultCondition(4)value indicates that a battery
installed has an internal error condition.