Yes, the 2500 mAh specification refers to the storage capacity of the battery. With this device, you can select the charging current yourself in reasonable steps; this only influences the charging time and (scholars argue about this) also the service life. In addition, there is also a "test" function with which you can determine the charge.
I bought this device especially for charging large 7000 mAh D batteries and am fully satisfied with it, except that the display is too small and some information can only be read with a magnifying glass.