Battery ....RIP,......... Death By Polar Vortex??

Daves69 said
12.3V before start.
Looks like it's runnin' high. Hovers between 14.85 and 15.03.
Top at batt. Center at alt.
View attachment 1715284171

That's pretty high charging voltage. Pry the caps off and see if the cells are dry. Sounds like overcharging to me. Distilled water to refill.