The disclosure presents a method and a hearing aid with an improved method for updating a discharge charging profile of a battery. The method comprises following steps; receiving during a first discharge step of the plurality of discharge steps a first primary battery voltage from a voltage monitor unit, receiving during the first discharge step a first primary charge from a charge monitor unit or a storing unit, determining a first secondary charge, where the first secondary charge is one or more discharge steps lower than the first primary charge, determining a first secondary battery voltage difference to be equal to a secondary battery voltage difference of a plurality of secondary battery voltage differences relative to the first secondary charge, wherein the plurality of secondary battery voltage differences is stored in the storing unit, determining a first secondary battery voltage to be equal to a secondary battery voltage of the plurality of secondary battery voltages relative to the first secondary charge, determining a first primary battery voltage difference between the first secondary battery voltage and the first primary battery voltage, determining a new battery voltage difference based on a first weight of the first primary battery voltage difference and a second weight of the first secondary battery voltage difference, and updating the discharge battery profile with the new battery voltage difference.