We claim the ornamental design for a storage battery, as shown and described.
FIG. 1 is a front elevational view of a storage battery showing the present design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a left side elevational view thereof; and,
FIG. 5 is a perspective view thereof.
Note that a rear elevational view is omitted since it is symmetrical to a front elevational view. Also note that the part illustrated by solid lines is directed to the article of the present invention. The broken line showing is for illustrative purposes only and forms no part of the claimed design.