My 2017 Newmar with 6.9 cummins voltmeter fluctuates at startup about 10-12 times, then settles down to 13+ volts. This started a few months ago. Bought 2 new chassis batteries , cleaned and tightend all connections, and it still continues. Does anyone else have this issue. The rv runs great 14k miles. Don't know if is alternator voltage regulator. 40 miles from cummins office