Good background. Kinda takes all the mystery out of the experience. Yes, without that cluster in place, only the luck of a bit of residual magnetism in the alternator rotor's core got you putting anything back into the battery. I've had the same experience, where the radio was my first clue the alternator had stopped charging, and that was _with_ the benefit of the idiot light in place.

Based on the fact the predominant number of Volvo strandings I've incurred have been the result of battery charging failures, I believe a low-voltage warning indicator or alarm to be more useful than the trunk full of spare parts some advocate.
--
Art Benstein near Baltimore

If a cow laughed, would milk come out her nose?