SOC drop - battery calibration issue?

[JustOnePanel]

This happened last night, what can possibly cause this SOC drop from 29% to 0%?

6000XP with 2 x EG4-LLs. Battery comms in-place and working, threshold to start charging the battery at 25%, back to grid threshold at 20%. System worked as planned, I didn't even know this happened till this morning. Just wondering what would cause this.

 

[sunshine_eggo]

That's likely cell imbalance. A single cell has hit low cut off, so it cuts to 0%.

Your batteries are likely imbalanced and only capable of delivering part of their total capacity. They need to spend extended periods of time at 100% to give the BMS time to top balance the cells.

 

[JustOnePanel]

That's likely cell imbalance. A single cell has hit low cut off, so it cuts to 0%.

Your batteries are likely imbalanced and only capable of delivering part of their total capacity. They need to spend extended periods of time at 100% to give the BMS time to top balance the cells.

thanks for the quick reply! Will top them off, with the winter low solar yield they spend very little time at 100% currently

 

[sunshine_eggo]

thanks for the quick reply! Will top them off, with the winter low solar yield they spend very little time at 100% currently

Very common for new/new-ish batteries that have never been deliberately top balanced to exhibit imbalance behavior in this situation.