Comparator Capacitor charge indicator
HVDC measurements are usually done with a capacitive transformer or a resistive transformer ( C or R Divider ratio)







simulate this circuit &ndash; Schematic created using CircuitLab

The series element connected to the HVDC must be rated for a voltage greater than what is measured.

There are other methods which use the internal design feedback coils and turns ratio to determine the peak current of charging the cap and voltage remaining from start to finish, but not always such as CC pulse chargers with voltage doublers.

Something like this.  THere are other chips with "LED bar driver" and built in comparators or use any Quad Comparator.