bq20z90

Try sending command 0x0021 to address 0x00 (Manufacturer Access). This should force an OCV reading and update the Relative State of Charge. If it doesn't update it correctly, then you likely have something wrong with your settings. What is your pack configuration (number of series and parallel cells)? Do you have a GG file? Did you load the chemistry corresponding to your cells? Have you calibrated the device? Have you gone through the learning procedure? These are questions that will need to be answered if command 0x0021 doesn't correct the issue.