The ornamental design for a portable powercharger, as shown and described.
FIG. 1 is a front elevation view a portable power charger showing a new design;
FIG. 2 is a rear elevation view thereof;
FIG. 3 is a left side elevation view thereof;
FIG. 4 is a right side elevation view thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a bottom plan view thereof;
FIG. 7 is a front perspective view thereof; and,
FIG. 8 is a rear perspective view thereof.
The shade lines shown in the drawings indicate the character and contour of surfaces represented and should not be confused with surface ornamentation.