Hi. I have read this with interest.
I'm getting very similar with the Growatt GBLI6532 battery. Tonight, no PV input, the load was largely consistent; SoC was at 20%, turned on the toaster which immediately added a large load and immediately SoC dropped to 9%. Not the first time I have seen this. I don't think there is a correlation with a large load being added, but the last two times it has happened a load was added. I'm going to investigate with my installer but would be really interested with any updates you might have. Thanks.