SLUUC54C February 2020 – March 2024 BQ27Z558 , BQ27Z561 , BQ27Z561-R2
Because temperature changes significantly during the course of a discharge, the algorithm needs to be able to predict the future temperature. This is required for temperature correction of battery impedance during voltage simulation near the end of discharge. To achieve this, the algorithm collects temperature-time dependence data during discharge. This data is used to update parameters of a simple thermal model, including a heat exchange coefficient, temp k, and a thermal time constant, temp k. These parameters are updated at the same time as resistances. The algorithm also records the outside temperature during relaxation periods. These parameters are used to define a temperature function T(t, T_start) that calculates a temperature profile starting from the present temperature, T_start, and continuing until the end of discharge in the simulation calculation.