Portable charger

FIG. 1 is a top perspective view of an ornamental design for a portable charger;

FIG. 2 is a bottom perspective view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a bottom view thereof;

FIG. 5 is a first side view thereof;

FIG. 6 is a second side view thereof;

FIG. 7 is a front view thereof; and,

FIG. 8 is a rear view thereof.

The broken lines shown in FIGS. 1-8 , that are immediately adjacent to the shaded areas, and define unshaded regions, represent the bounds of the claimed design, while all other broken lines are directed to environment and are for illustrative purposes only; the broken lines form no part of the claimed design.