Interesting charging graph
Still you don't share all the info here
Does this graph start when you start charging the car, or after some seconds/minutes ....
Above you mention "Started at 25.4% and is now at 29.something"
Looking at some screen shot of my EvBatMan (almost 1Ah less time ago) .. I see 3.80v at 28.5% ..and 3.815v at 29.5%
So ... per what you said ... 25.4% is for you 3.82v
And 29% is 3.85v
So .. it is looking SOC and resting volt ... is something "remapped" for each PHEV
Is looking like the charging process stop after 10min .. and has a balancing pause for 15minutes ... which I don't understand the logic ... possibly the pack is seen too unbalanced for continue on normal charging .. and pause until the balancing level is acceptable for continue charging ... just a guess .... hard to know what is the logic here ... it can also be used for measure the IR under a know charging current ....
Also ... it is not visible what happen after 3.98v (with load) .. which apparently you got only after 25min of charging from 3.85 (unloaded) / 3.885 (with load) .... 388v to 3.98v in 25min ... does sound quite fast to me .. but possibly you use 16A charger .. still it is "fast" .. so a sign of a weak battery capacity)
What we also don't know is when and which cell get balanced at any time ... it will be an important information to know what the BMU is doing ... when I charge my hobby Lithium battery ... I know all the time which cell get balanced at any stage
PS: How can you track these info ? ... my OBD2 adapter is not working when the car is "off" or it is connected to the J1772 plug (even if not under charging)