The learning cycle process consists of charge – relaxation – discharge – relaxation – charge while certain data memory parameters are set in the gauge, enabling the gauge to begin the cycle and accurately recognize when state changes have occurred over the charge/discharge process. Through the course of the learning cycle, the [LStatus] register updates as different states are achieved, marking three points in the progression of the learning cycle.

The first [LStatus] update goes from 0x00 to 0x04 when the gauge has had the Impedance Track bit enabled, allowing the learning cycle to begin. [LStatus] goes from 0x04 to 0x05 when the post-charge relaxation has allowed the battery to relax enough so that the change in voltage is very low (dV/dt < 1 µV/s). The [REST] flag will be set indicating that the battery has adequately relaxed. The final [LStatus] update to 0x06 happens after the second discharge when the change in voltage is very low.

For more details on the register updates and flags set at each point in the learning cycle, see the Learning Cycle Procedure section of the Achieving the Successful Learning Cycle.

For more details on the learning cycle registers, refer to the BQ27Z855 Technical Reference Manual.