Originally Posted by dunk05
works pretty quick or just drive around a little
While you might think this works, you will never get more than 5 or 10% capacity replacement doing this. The voltage will mostly recover quickly but the capacity takes a lot of time.
Ignoring the tapering off of charging current as the voltage comes up (the alternator is a single stage charger) and say "on average" the alternator charges at an average 7 amps (if does NOT as on average it is MUCH less); it will take OVER 10 HOURS of "driving around" to charge up a 75 amp hour coach battery.
The physics is complicated but here are some charts to provide the visuals.
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW