I claim the ornamental design for a battery charger, as shown and described.
FIG. 1 is a front perspective view of the battery charger showing my design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a top view thereof;
FIG. 5 is a right side elevational view thereof;
FIG. 6 is a left side elevational view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is a rear view of the battery charger with the electrical plug shown in the rear view turned to extend outward from the rear and with a cable attached for use therewith.
The cable shown in FIG. 8 is shown for illustrative purposes only and forms no part of the claimed design.
The broken line showings in the figures are for illustrative purposes only and forms no part of the claimed design.