ok right the level of battery is not updated.

But you can rely on voltage.current and voltage.design to approximately determine the remaining time, with the same method as above.

And better, you can check at the first launch of your program the voltage.current when battery is considered as full, to know what's the max level the battery can achieve.

Because everyone can have a battery with a max voltage different, so once again I don't see how the results sent by users will help you.