Apple’s official Smart Battery Case for iPhone isn’t as smart as it could be…
Quanta smartly combines the battery percentage of your iPhone and Smart Battery Case in the status bar. As batteries wear down over time, Quanta takes into account the usable capacity of your batteries to provide a more realistic view of your battery life. It will only show as charging when the Smart Battery Case itself is charging. The charge percentage of each battery is also displayed by opening the Control Center.
Quanta also provides some useful data on your battery health in the Settings app.
iOS 13 only for now. If you think Quanta would be useful on iOS 12, let me know!