Don Cooper, via email
First, make sure that you’ve connected the USB cable from the back of the UPS to a USB port or hub on your Mac. Without that connection, your Mac won’t know that it’s attached to the UPS.
Now launch System Preferences and select Energy Saver. You should see a UPS tab. Select it and you’ll find options for configuring the UPS.
These options are similar to what you see when you select the Power tab in this system preference – computer and display sleep times, and options to put the hard drives to sleep and restart the Mac after a power failure. To view more-arcane options specific to the UPS, click the Shutdown Options button. Here you can set limits on when to automatically shut down the computer running on UPS power.
You have the options to shut it down after a specific amount of time (from one to 15 minutes), when a certain number of minutes remain in the battery’s charge (again, from one to 15 minutes), and/or when the battery level reaches a particular percentage.