@spicedreams I will check when I install my Quattro inverters and will report back to you.
With my Sunny Islands it has been working great for a few years, but I had lead acid batteries. So charge current would decrease gradually and frequency increase gradualy too.
Now with my lithium batteries the Sunny Island has a software bug that when generator is off, it will set the charge voltage 1V less than what it receives from CAN bus from the BMS. So it will start throttling my PV inverters quite soon when my betteries hit 51V instead of 52V. So, being fixed at 51V charge current also starts to decrease gradualy. This is how my frequency looked for today for example (PV throttling starts at 51Hz as in the graph above)
When I have my new inverters installed should be able to charge to 52V at a constant current, so I imagine it will be more abrupt when I reach 52V and switches to float voltage. So will update here on how frequency and dump loads behave, but I still think it should work ok
Edit: I get these graphs polling through Modbus every 5 seconds. I do not remember how often VRM polling is. So maybe it is just a lack of resolution