The ornamental design for a battery for head mounted display device, as shown and described.
FIG. 1 is a perspective view of a battery for head mounted display device showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof;
FIG. 8 is a reference view thereof showing the way of the subject design being attached to the head mounted display device; and,
FIG. 9 is a reference view thereof showing an example of the usage of the subject design.
The evenly broken lines depict portions of the battery for head mounted display device that form no part of the claimed design. The long dash short dash lines in FIG. 9 depict environment that forms no part of the claimed design.