Mr ERFisher wrote on Sat, 25 March 2017 08:01

Your earlier post said you removed it
Barton told you the alternato volts should be 15 volts
Read here
http://www.gmcmotorhome.info/engine.html#alternator

Is prob not the APC

15V sustained is too high, except in sub-zero tempeatures. But 13.6V minimum, generally. More than 14 after a long starter crank.