At Midnight my batteries were reading 49%, previous day had produced little generation from solar panels. Then without any apparent reason the batteries discharged from 47 to 13% at 05:10 this morning. I have no idea why as none of the settings on the battery had been changed and discharging power from the battery into the grid is not something we ever do.
BrianNWakely did they discharge (send power to home or grid), or did the reported SoC just drop?
It is not uncommon for the reported SoC to spontaneously change. The BMS has trouble tracking the true SoC, and, particularly when the battery idles for a while, or when you discharge at high power, it realises it was storing less energy than it thought.
This happens particularly if you don't regularly charge to full and discharge to empty, which allows BMS to update its estimates.
There's a video on the official YouTube channel encouraging users to exercise their battery from time to time.
Thanks DD for your response. The battery spontaneously discharged yesterday evening and again early this morning, with a break between. As far as we can tell it did not discharge into the house or grid so we assume it just dropped. The battery is now at 6% so we intend to charge overnight to see if this resolves the problem.