You apparently have a 1998 coach and alternators and voltage regulators have changed a lot over the last 20 years - especially around 2005-6. That being said, if your coach has been sitting for a day or two, after you start your engine the alternator should be putting out about 14.1+ volts to charge up your depleted starting battery. At some point when the starting battery is sufficiently charged the output should drop down to around 13.5v. If the alternator is not initially putting out 14.2v it could be an alternator or voltage regulator issue or a bad cell in your battery or a bad wire.
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