happens to me before, wiring issue (later found out to be rat bite).
when driving, suddenly loose power. radio died, lights dim.
i can still drive so long i maintain >2k rev, alternator still supplying just enough power for vital components like hydraulic.

i noticed the issue & exit on next petrol station.
as i glide to a stop, rev drop, engine died, steering bcom stiff bcoz lost hydraulic, & it will lock up if i turn the wheel.
but managed to bring to a safe place to stop, pop the hood, giv the battery & alternator a couple of wack, then able to start bck.
i quickly to workshop.