6LOW BATTERY Status Indicator
When lit (orange) it indicates the battery pack charge level is low. When this indicator turns on it indicates that there is minimum, time remaining. The purpose of this warning is to allow time to shut off power to the equipment before the battery pack is fully discharged. The user can set the value (from 2 to 25 minutes). When the indicator is lit, leave the unit plugged in to allow batteries to recharge.
Note: The unit does not have to be powered on for batteries to recharge.
7LINE OK Status Indicator
When this indicator is lit, it indicates the input voltage from the utility is within the acceptable range (90V to 144V) for the S10 and S15. If it is not lit, the input voltage from the utility is outside the acceptable range, and it will go into boost mode or trim mode to compensate for the (low or high) incoming AC line voltage.
8FILTERING Status Indicator
When this indicator is lit, it notifies the user that the electromagnetic interference and radio frequency interference (EMI and RFI) noise reduction circuit is active.
9OVERLOAD Status Indicator
When lit (red) the unit is overloaded; unplug the devices connected to the unit one at a time until the indicator is no longer lit.
10Down Arrow Push Button 
This pushbutton is used to change (decrease or turn off) parameters for various
Display Dimmer, LED Dimmer, Go To Bat If, Outlet 1 & 2 Delay (in seconds), Low Bat Warning, Bat Rep Date, and so on.
11On/Off Switch
This switch controls power to all of the 12 outlets located on the rear of the unit. APC recommends the unit be left ON at all times. Control power to your system components as you normally would, instead of using the S10/S15 On/Off Switch.