Sudden Battery Discharge CATL
Hi,
Since the batteries have been installed (added to the inverter) mid December 2022, the slave battery has twice suddenly fully discharged for no apparent reason. The first time this happened was on the 2nd January 2023 (4am) and the battery temperature had dropped slightly below 12 degrees. The issue was reported to Sunsynk Technical support and they updated the firmware for the batteries. Since then, all has been good, until Thursday evening (7pm) on the 16th February 2023, when the slave battery fully discharged again (temperature was above 12 degrees). Firstly, where does the power go? Secondly, why is this battery doing this? At the time of both discharges, the load was less than 200w. The battery level was 30% the first time and 23% the second time.
For reference, when this occurs, the alarm in the inverter activates and the slave battery then automatically charges from the grid. The batteries are not in parallel due to the master having 23% and the charging is for both. I have noticed now, that when I grid charge to 100%, the slave will requires a continuous charge of double what is required to be full. In layman’s terms, once the master reached 100%, the slave was approx 77%. So this would normally be another 2.3kw to fully charge, yet, it takes double this, as the inverter will keep supplying about 2kw from the grid, yet in one hour, it will only increase 10%. The batteries also never appear to reach 100%. On very sunny days, the solar will just keep going to the batteries on 99%, yet it will not go to 100%. The solar will also not divert to the grid.
My inverter timer settings are mapped around Octopus Agile, meaning when the power is cheap, the inverter will not take power from the batteries and when the power is expensive (normal price), the inverter will use the batteries to power the house.
looking for guidance here, as Sunsynk technical support are either unwilling or unable to tell me why these events are occurring. Frustratingly, I have been looking after the batteries in terms of not fully discharging (the most I have taken them down to is 20%) to prolong the life, yet the one seems to want to not ‘live long and prosper’!
Any guidance would be welcome👍