SmartShunt300A_wrong connection_history

The only way to reliably get the SOC correct is to perform a full charge where the controller reaches float and the SmartShunt synchronises to 100% or you set it to 100% mamually.

As you have made one of the two common mistakes, here is a link to the other, not setting the SmartShunt settings properly. Both ate covered in the manual.

And for completeness