Even if the control of current flow into house batteries were Ideal, one's house batteries are still at the mercy of the vehicle's voltage regulator which is more concerned with not overcharging a single barely discharged engine starting battery.
Most people take a voltage reading once at idle and will proudly declare my alternator puts out 14.2v, but the sad fact is the voltage yoyo's all around with load and rpm, and is never ideal for proper recharging of depleted house batteries.
UNless of course one can control their vehicles voltage regulator.
My VR was in my engine computer and would choose 14.9v, or 13.7v and very rarely 14.1v. it would decide 14.9v when the batteries were full, and 13.7 when they were not, and 14.1 just to screw with me.
With Mex's help, I now decide on the vehicle target voltage with an adjustable regulator to Which I added a remote potentiometer to and mounted it on my dashboard next to 3 wire digital voltmeters. 3rd wire is voltage sense.
Amazing, well not really, how many more amps flow into depleted battery, when I choose 14.7v, compared to 13.7v.
Alternators with internal voltage regulators can be modified for external regulation. Balmar makes 3 stage voltage regulators with adjustable setpoints and durations and all sorts of bells and whistles.
I find twisting a potentiometer dial located next to a voltmeter to release more serotonin than a 700$ voltage regulator ever could.
