Battery Health Detection

Hi All....

I am working on programming Zigbee microcontrollers, i have implemented many things for RF communications.. Now my aim is to dynamically track the battery health level of each Zigbee node and display these level on LCD attached with Controller board/coordinator. Can anybody tell me how to accurately determine the battery remaining charge? just like battery level is shown in Laptops and Mobile phones.
I would be really thankful if someone suggested a circuit for it.

Bro you can use that (https://www.ti.com/tool/boostxl-battpack) design features and if u want to design your own controller(https://www.ti.com/lit/ds/symlink/bq27510-g2.pdf) use . that used in boosterpack ic - provides to measure battery feaures.