Excellent write up Mex.
Your theoretical depleted 27's amp draw from a 130 amp alternator nearly exactly matches my observations.
My voltage regulator allows 14.9v, but will prematurely drop to 13.7 or 13.9. Where as it might have taken 65 amps to hold 14.9v, it only takes 13 amps to hold 13.7v. The VR is in the engine computer so I am not going to worry about the premature 13.9/.7. Sometimes just flicking on the lights or blower motor briefly will ratchet it back up to 14.9, and other times it just seems to go back up there for no apparent reason. So be it.
My depleted batteries always seemed to respond well to this Massive Morning alternator blast of bulk current. Much better than if my solar alone were to take and hold them in the high 14's / low 15's for several hours.
I've seen my current group 31 take 65 alternator amps for about a minute before voltage climbs to 14.9v, but I need to adjust/replace the V belt as it now starts screeching at that level on a damp morning.
Lets not forget the importance of proper cabling from alternator to house bank. I think too many people take power for the house bank from the starting battery, which leaves the OEM charging circuit as the weak link.
Amazing how a fused cable from alternator(+) directly to house bank or solenoid, in parallel to the OEM circuit, allows significantly higher amps to reach depleted house batteries.
I have a circuit breaker on my doubled 4awg parallel circuit. If I deactivate this parallel circuit, current into the battery can be cut by 2/3 with depleted batteries and enough rpm to make a difference.
Perhaps some wish to baby their alternator with thin wiring. Not me. If the batteries are thirsty I'll let them drink through a doubled mcdonalds straw, not a single kinked cocktail straw, and my Current alternator has been subjected to this "abuse" since 2006.
