NOt so easy to perform the Concorde conditioning procedure on a generator, and while still cycling the batteries.
My Northstar specs a 14.46 @77f absorption. I have been using 14.7v for most of its life.
It's holding 12.3v under a 14.6v amp load with 22 Ah removed from its original when new 90AH capacity, at I type.
Your batteries are out of warranty, and they are likely not dried out from overcharging, most likely sulfated from thre opposite, so I'd not fear a few more tenths of a volt for absorption.
And you need to hold absorption not to "100%" as indicated by your meter, you need to hold absorption voltage until amps taper to 4.
If amperage ever tapers to 4, then perhaps you cn consider them at that point, 100%. and then reset your battery monitor, and still eye the Effing thing with a bucket load of suspicion, scorn, derision and possibly contempt.
Give up on the percentage readings of your battery monitor.Its readings are likely false and are likley responsible for the condition of your lifelines. So ignore it.
read these a few times:
https://marinehowto.com/installing-a-battery-monitor/
https://marinehowto.com/programming-a-battery-monitor/