@peerv in my situation, if i click on any of my child devices, like temp, lux, humidity, etc. i can see the battery level. so i have to create a new sensor, in this case i'm creating computer_room_15_0, and i pull the value from child 1, i could pull it from 2,3 or 4, but i chose 1. and the value that i'm pulling is an attribute of child 1 called battery_level
now that i have created that sensor. i can place it where ever i want.
so the newly created sensor computer_room_15_0 is my entity_id that can go in a card or whatever.
before you do that, i would trouble shoot in the following way.
- pick a child device and open it, ensure you can see the battery level.
- create a new sensor based on the template above (restart after)
- go into the the states dev tool page and ensure it's there and has the correct value.
- if yes, then open the standard states based screen see if it shows up at the top in the circle.
- if yes, put that entity in your lovelace ui as you see fit, if no, go back and figure out where it's not working.
you can also tail the log file and you restart and look for any error messages that may offer a clue to why.
here is my states screen for the battery sensor.