Alternator/Voltage Regulator problem

[bbwlwb88]

I am having an intermittent problem that started about 3 weeks ago.
Sometimes, when starting the engine, my alternator pegs at maximum
output (300 amps) and the coach batteries peg the gauge at maximum
voltage charge (18 volts). The cranking batteries charge shows only 12
volts when this happens which indicates to me they aren't charging at
all . If I shut down and restart the engine several times, the
alternator and the charging voltage on the coach batteries and engine
cranking batteries eventually will work correctly. Normally, when
starting this coach, the engine starts and the alternator goes to 300
amps and then drops quickly to normal output (30 to 40 amps) and the
coach batteries, as well as the engine cranking batteries, charge at
their normal level (about 14 volts). The engine is a Detroit Series 60
with the large alternator.

I would appreciate information on what should be done to identify and
correct this problem.

Royal Washburn
'97 43'WB