If the state of charge – also called SoC – does not reach zero when the battery is discharged, it is because the battery has not been able to perform cell balancing over a period of time. Under normal circumstances, cell balancing (also known as "calibration") happens automatically if the battery is charged to 100% using power from the solar panels or if a full charge has been manually completed. However, if there are only a few hours of sunlight, such as in winter, the battery may not become fully charged. In that case, cell balancing may not occur.
If the issue persists, please contact ServiceX support at support@servicex.dk or by calling +45 35 153 123, followed by 2. Remember to provide the support agent with your device ID, also known as the SCR number.