I could never get the battery life working in HG and not sure why some see that and others don't.
You can remove that displaying item but I've never looked into adding it (seemed useless if it wouldn't work for me) I could set the value but it never changed (maybe I just didn't watch it long enough)
Update: Here is how to add the battery to existing sensors and change the value.
1:in the group the sensor is in click Actions/Configure Group
2:scroll to the sensor you wish to add the Battery to or edit its value
3:click on the Parameter icon for the sensor
4:Find an entry your not using (with a blank field) like "HomeGenie.ZoneSensors.5" and change the name to "Sensor.Battery" in the blank field type 100
5: Click save
6: Click Home, the 🔋 should appear and be full
Now there may need to be another thing added to make this work.
To delete the battery sensor just click delete after highlighting the Sensor.Battery line or set the field to nothing