Well that is unfortunately not what you suggsted here and perhaps you didn't check my graph carefully. I uploaded 2 more pics. The left graph shows the SOC and the right graph shows min/max cell voltage. If you know LTO well then you know it has been changing something like from 50%to60% up to 80%. It was charging with 200W in the middle of the day, and my battery pack is only 2KWh capacity. So it actually charged around 10% per hour during the mid day. Or you can view it directly on my shared dashboard above and click onto the advanced tab. It has been charged with more than 8A from 12:33 until later after 5PM the sun goes down, the SOC is capped and not moving at all. This is a firmware bug, I suppose. And I could not get any help from the seller than telling me "top charge it and then set SOC to 100% again". But I already did exactly this 2 or 3 days ago as it was way off and capped at 49% for some reason by then.
I feel Daly's BMS's software side (also they cannot read current blow 2A) is not polished and just a "fancy look" product. I then ordered some QUCC BMS and they arrived today and I set it up earlier on my other battery pack and they work nicely (amps reading can be as low as 0.5A). I haven't figured out is how to set the SOC on QUCC BMS yet, as it is late in China now, I will ask the QUCC seller tomorrow. (Their tech support, or the seller, is also much better)
From the software config page it feels the Daly system is doing very stupid amps monitoring and calculate the SOC solely based on that. It considers nothing with your voltage change. The QUCC BMS seems doing it more "smartly" or what I feel is the standard way of estimating SOC - you combile amps reading and battery voltage reading.