MIB: PowerNet-MIB
The date when the UPS system's batteries were last replaced
 in mm/dd/yy (or yyyy) format. For Smart-UPS models, this value
 is originally set at the factory. When the UPS batteries
 are replaced, this value should be reset by the administrator.
 For Symmetra PX 250/500 this OID is read-only and is configurable in the local display only.