Despite Refresh and although the (old Eneloop) battery charger really loud were still good, I decided after 3 years to an exchange. Gut feeling ... And yes, the Gigaset S44 handsets have significantly more stamina again.
A device that inexplicably Fully charged should always be neither abschaltete running smoothly again.
My tip: Often (every 3 years?) Times change the batteries. The Eneloops. Other Batteries I do not buy for a long time!