CCCV is the standard Constant Current to Constant Voltage control, while CCCV_WRM inserts a very short ‘relax’ period between CC period and CV period. During relax time, system current output drops to almost 0, and the corresponding load voltage drop will be measured by the system. Then an Internal Resistance value is calculated by IR = voltage drop / Current drop. This IR value is used for CV stage voltage control (current based PID control). Advantage of CCCV_WRM: It provides the latest IR value for best Voltage control, it also eliminates the need of adding an IR step before voltage control. The disadvantage of CCCV_WRM: There is an extra current drop in relax period which does not exist in standard CCCV. Also, the IR value calculated may be less accurate if the CC value is too small to create an effective voltage drop.