Earlier today I went to the library to work, to get a change of scenery. Shortly after I sat down, I glanced at the SystemPal icon on the menu bar: it showed an operating temp of about 180 F. Then I glanced at the Activity Monitor icon on the Dock: it showed high CPU and Energy usage. Both apps said CommCenter was the culprit. Restarting the computer did not stop CommCenter from draining my battery. After searching here and on the internet in general, all I could find were references to iPhones and iPod Touches. There is almost nothing about CommCenter on OS X. Thinking it might have something to do with WiFi Calling, here's what I did to stop CommCenter: I opened FaceTime and unchecked "Calls from iPhone." I rechecked the box but didn't click on Upgrade to Wi-Fi Calling. I like taking or making calls on my computer but since I always have my phone nearby, I don't really need to make Wi-Fi calls on my computer. Battery drain fixed. Hope this helps someone else who runs into the same problem. Our cell carrier, or Un-Carrier, is T-Mobile.