I’m no expert either, I learn by the seat of my pants …
Theoretically, all the cells should discharge at the same rate, T&C’s like resistance per cell being similar and all that.
When discharging the 100ah cells drop faster, obviously, the Delta increasing quite a bit, expected, the 280ah taking “their time”.
When recharging, the Delta starts “wide”, yet “shrinks” as the 100ah cells are charged.
Why the 280ah cells are not “running” away, my “theory” is that the 100ah being more discharged, absorbs the charge faster than the 280ah, still being relatively charged.
At the top, THERE they must all “settle” with a Delta below 0.008v or some such.
The system has been sitting for hours at 97% SOC, 58.56v, and climbing, with a Delta of ±0.0010v as they head for 3.45v or 58.65v, where Victron will also stop.
This teeny bit of current being too small to register anywhere, helps to balance at the top, therefore the cells balancing themselves at a leisurely pace whilst the house is being powered with all the panels can provide.
Ps. As I was typing, the volts hit 58.68v … balancing stopped, now I watch if it goes above 58.75v … or I will have to intervene, like recently I figured, if I want the system to discharge NOW … switch on both ovens!
Like now, to force a fast hard discharge, the ovens my only recourse …
But so far all is holding nicely …