Mine is a 1976, my A&P says it is low equals a charged battery ie. good
Went over today to check it over, not really up to it last night sure enough a shredded alternator belt, off the pulley and delaminated, but still a ring even if only just.
Best thing really, cheapest alt failure to fix
I have to do something about making the low/fail voltage visible, thinking a UK style light in addition the annunciator; had this happened ahaof an hour earlier, this would have been a tale of going swimming and judt how difficult it is to get into a raft!
As soon as the belt is on over to Mustique for the training to land there, not as scary looking as St Barths but close to Barbados so I will be able to keep it current