The ornamental design for a batterypack, as shown and described.
FIG. 1 is a front perspective view of a battery pack according to our design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is a front perspective view of the battery pack with a main battery pack shown in broken lines. The main battery pack is environmental only and forms no part of the claimed design.
The broken lines in the drawings illustrate environmental subject matter only and form no part of the claimed design.