Ron,
IMHO, do this before you do anything else:
Run your coach batteries down a bit, then find the solenoid in your PC that hooks the alternator to the coach batteries, then start up the V10 (this should automatically switch ON the solenoid), then use a voltmeter to measure the voltage on the (incoming) engine alternator side of the solenoid, then measure the voltage on the (outgoing) coach battery side of the solenoid. Compare these two voltages - if they're not equal to each other, then your solenoid is part or all of your low charging current problem and needs to be replaced before you proceed with any other changes.
AFTER YOU DO THE ABOVE, then proceed with further troubleshooting and changes. What DiploStrat talked about in his excellent post above is good stuff - but there are other very good comments earlier on things to try, too.
Note: The cable size DiploStrat talked about is very large. My Winnebago cabling size between the alternator and coach batteries is only 6 AWG ... and I do see up to 50 amps at an initial ~50% state-of-charge going into my 200 amp hour AGM coach battery bank with this cable size. However, the total cable length between my coach batteries and the alternator is probably no greater than 8 feet.
