Thank you for your reply, which confirms my assumption regarding the counting down and up.
I also searched for any relevant topics and must have read through about twenty or so before starting this thread, but as soon as I posted this, the topic “BMV 712 Smart 100% state of charge too early” appeared at the top of the related topics list beneath my post, and in that thread @pwfarnell confirmed the same thing:
I think the reason that I never experienced the BMV resetting to 100% outside of the conditions determined by the charged voltage/tail current/charged detection time settings with the old batteries was because it overstated the amount of discharge, as I had deliberately set the battery capacity 10Ah lower then their stated capacities, so it probably always resynced on the synchronisation settings before the Coulomb counter returned the calculated net deficit to the batteries.
With the lithium battery, I found that the BMV was quite markedly understating the SOC compared against the counted Ah deficit, and I have had to disable the Peukert setting completely to bring it anywhere near to the %SOC and Ah discharged figures agreeing with each other as calculated against the battery capacity.
I think I will experiment with reducing the CEF to see if that will reduce the early 100% reading from the Coulomb counter calculation.
As for reducing the charging voltage to 13.6 V, I understand what you are saying, but my B2B and Solar chargers, neither of which are Victron units, only have options for Lithium charging settings of 14.4V/13.8V and 14.2V/13.6V. The battery manufacturer recommends 14.4V and charging until one cell hits OVP, but I already decided against that and settled for the 14.2V/13.6V algorithm. I have my IP22 charger set to 14.2V bulk/absorption, with no float and 13.25V storage, as I don’t anticipate leaving it on continuously, only to fully charge the battery periodically.
The battery has both active and passive cell balancing, both of which are only active above 3.4V per cell, so as I see it, only charging to a maximum of 13.6V would mean that balancing will never happen.