Battery cage

1. 1The ornamental design for a battery cage, as shown and described.

FIG. 1 is a perspective view for an embodiment of a battery cage;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a back elevation view thereof;
FIG. 4 is a left elevation view thereof;
FIG. 5 is a right elevation view thereof;
FIG. 6 is a top elevation view thereof;
FIG. 7 is a bottom elevation view thereof;
FIG. 8 is a perspective view for another embodiment of a battery cage;
FIG. 9 is a front elevation view thereof;
FIG. 10 is a back elevation view thereof;
FIG. 11 is a left elevation view thereof;
FIG. 12 is a right elevation view thereof;
FIG. 13 is a top elevation view thereof; and,
FIG. 14 is a bottom elevation view thereof.
The dashed lines in the drawings illustrate portions of the battery cage that form no part of the claimed design.
The surface shading and contour lines (including any CAD or wire frame lines) in the drawings is a drawing convention to represent character and contour; it does not illustrate material, surface ornamentations, or surface decoration and forms no part of the claimed design.