Question about Powerline 5 Pro - 434500

Hello, why is it not possible for me to fully charge all the batteries? have to recharge them every two days 😡 although I previously discharge them as described in the booklet: Discharge and later charge the batteries (+NIMH 4500 mAh-also all from Ansmann) in the respective only outermost compartments set to 1800 mA??. Who can help me further? Thanks in advance.