Question about Ansmann Energy 16 Plus

No capacity is specified for the current unit.
It is important that the batteries are designed for the charging current of the unit.
The following charging currents are specified for the current unit:
400 mA Micro AAA
1000 mA Mignon AA, Baby C, Mono D
60 mA 9V block

In general, the battery capacity should be at least large enough so that the C rate is NOT higher than 0.5 C when charging. Otherwise there is a risk that the battery will be damaged by the excessive charging current (less is better here, but it takes longer).
Calculation example:
Battery with 1000mAh is charged with a charging current of 1000mA --> C-rate = 1.0 --> not good, capacity too low
Battery with 2000mAh is charged with a charging current of 1000mA --> C-rate = 0.5 --> minimum capacity

Batteries can be charged up to a C-rate of 0.1 without any problems - charging then simply takes much longer.
In the case of AA batteries, this would mean that batteries with capacities of up to 10,000 mAh can be charged without any problems - there are no such batteries on the market.

As a comparison:
The PREVIOUS MODEL (Ansmann Energy 16) had the following capacities (whereby the minimum capacity should be higher in my opinion because the C-rate is sometimes even higher than 1.0 and this is not good for the battery):
Micro AAA 180-3700 mAh (charging current 300mA)
Mignon AA 500-8500 mAh (charging current 700mA)
Baby C 1200-14000 mAh (charging current 1000mA)
Mono D 1200-14000 mAh (charging current 1000mA)
9V Block 100-400 mAh (charging current 70mA)