The present invention relates to a charger device (100) comprising: a sensor (10) which is configured to measure a differential current (DELTA_I) as a difference between a first current (I_POS) through a first battery portion (210) of a battery (200) and a second current (I_NEG) through a second battery portion (220) of the battery (200) and which is configured to provide a current difference signal (ΔI_meas) based on the measured differential current (DELTA_I); a compensator (20) which is configured to calculate a first current setpoint (I_SP_POS) used for the first battery portion (210) and a second current setpoint (I_SP_NEG) used for the second battery portion (220) based on the provided current difference signal (DELTA_I) and a battery current setpoint (I_SP); and a controller (30) which is configured to control charging and/or discharging of the first battery portion (210) based on the first current setpoint (I_SP_POS) and of the second battery portion (220) based on the second current setpoint (I_SP_NEG).