We claim the ornamental design for a cart power module, as shown and described.
FIG. 1 is a perspective view of a cart power module showing our new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a right side elevation view thereof;
FIG. 5 is a left side elevation view thereof;
FIG. 6 is a rear elevation view thereof; and,
FIG. 7 is a front elevation view thereof.
The broken lines showing portions of the cart power module are for the purpose of illustrating environmental structure and form no part of the claimed design.