Interesting thread.   I have an optima yellow top as my house
battery, and have chronic under-charging problems.   I recently
bought a new bosch alternator as my old one was failing (I think) and
added thicker wire and a new relay to charge the house battery, but
even thus my optima rarely charges to above about 70% ish (12.4v)
even after a full day of driving.   Voltage when driving measured is
about 13.5V at the battery.

1. Is there a chance that my brand new Bosch alternator is
adjustable?  What model #s do that?

2. If not, as a cheezy workaround, what if I put in a battery
charger.  How about a 120VAC one that could run off an inverter
connected to 12V supply.  Or maybe a DC-DC charger?   Assuming I
don't create a black hole or something, seems like the charger could
deliver higher than 13.5V and get the durn optima fully charged, no?