I apologize for the humongous bump, but I believe it will be of some note to add that the package called "libunwind" controls how the battery information is displayed in KDE(at least in KDE, haven't tested on others)

I almost tore down everything before remembering that I messed up this package dabbling with something completely unrelated.(Or at least I THOUGHT it was unrelated at the time)

If the output of

"cat /proc/acpi/battery/BAT0/state"

gives correct information regarding the charging state, remaining time etc etc, then you should check and re-install the "libunwind" package

This was, at least, what solved it for me, although my symptoms were exactly the same as the OP.