We claim the ornamental design for an interface of a battery pack, as shown and described.
FIG. 1 is a front perspective view of an interface of a battery pack, showing our new design;
FIG. 2 is a rear perspective view of the interface of the battery pack shown in FIG. 1.
FIG. 3 is another rear perspective view of the interface of the battery pack shown in FIG. 1.
FIG. 4 is a first side view of the interface of the battery pack shown in FIG. 1.
FIG. 5 is a second side view of the interface of the battery pack shown in FIG. 1; and,
FIG. 6 is a rear view of the interface of the battery pack shown in FIG. 1.
The broken lines represent unclaimed subject matter and form no part of the claimed design. The dash-dot broken lines represent boundary lines. The dash-dot broken lines themselves form no part of the claimed design.