On generator you stop the charge at 80 or 90%. the last bit top "full" would take forever.
How to tell when to stop? the boost lasts four hours when you put it there manually so that is longer than you need as seen above, so you stop at the amps marker for 90% (5 amps per battery) so when amps taper to 10 amps with two batts.
If you want to stop at 80% or 85% just look at the above graph and see what the amps are for that SOC and adjust for the number of batts you have. it is proportionate. Four batts you stop at 20 amps instead of stopping at 10 with two batts.
If your charger does not have an amps read-out and you don't have an ammeter Trimetric, whatever, then use the ugly graph times and just stop when you have run that long.
Another way to do it is suggested by smk on here, that you let it run till your batts reach 14.4, then run it for one more hour and stop. You can see that would work by looking at the ugly graph