They previous owner may have left the batteries on a charger too long and killed them. Don't ask me how I know. I will deny ever doing that. I actually have a dead battery now. My 60amp alternator in my APU will not charge over 12.8 volts. Should be up around 13.7 to 14.0
So the shop put in 4 new Champion batteries. 950 cold crank amps each. I'm hoping this takes care of the problem. I really appreciate all the input fellas. I'll update tomorrow while I'm out working
Have 2004 Volvo vnl When ac's on voltage drops from 13.9 to 13.2,3,4 Alternator fine,new starter,new batteries... Any idea? 3 mech said leave it
check your voltage at the battery's and the alternator. you may find you still have full voltage at the alt but not the batterys or the batterys but not the cab. witch would indicate a bad connection between point a/b/or c if you have the same voltage drop at the alternator as your dash gauge might pickup a spare alternator and throw it in the side box might be getting a bit weak.