If you have some idea about electronics and has a correspondingly fine soldering iron, the replacement of toothbrushes batteries is not a problem.
The two batteries are ordered as described. The measured capacitance is even slightly higher than printed. After previously 3 charge cycles our toothbrushes hold finally a whole week at two-time usage per day.
Absolute buy recommendation. It should be noted only that the battery (4 / 5A) will only fit into the big, expensive toothbrush models. The smaller à la popular toothbrush, 500, 550, 600 and so need a smaller 4 / 5AA battery because they have a slightly different battery compartment.
