I have seen a similar issue in another thread 6 month ago but without a clear reason/solution. Perhaps now the issue is more known and already solved
I installed 5 days ago an off-grid system composed by 2 x pylontech US5000, smartsolar 250/85, cerbo gx, multiplus II 48/5000/70-50 and a 3000w solar grid prviding 150V and 25A.
When i connected batteries to the off-grid system they were at 49% charge and they reached 100% in few hours.
2 days later theymoved down to 89% as it was a raining day and solar panels did not produce power.
After that the batteries stay at 91% charge. SmsrtSolar only produce the energy required to feed the load. Load is quite low as I was testing system before connecting high loads.
Firmware versions in smartsolar, charger and multiplus are the latest one.
Why does the charge percentage stay at 91% if load is very low and there is enough PV power to increase batteries charge?
DVCC is enabled, charge current limit has not been reached and there is not voltage oberload alarms.