This value will be fixed for devices powered by a single source. This value may change for devices able to transition between multiple power sources (mains to battery backup, etc.).<br/>
The default polling rate for this function set (this resource and all resources below), in seconds. If not specified, a default of 900 seconds (15 minutes) is used. Clients SHOULD poll the resources of this function set every pollRate seconds.<br/>
If the device has a battery, this is the time since the device last switched to battery power, or the time since the device was restarted, whichever is less, in seconds.<br/>
If the device has a battery, this is the total time the device has been on battery power, in seconds. It may be reset when the battery is replaced.<br/>