I claim the ornamental design for water-charger for robotic air purifier, as shown and described.
FIG. 1 is a front/right-side/top perspective view of a water-charger for robotic air purifier showing our new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is a left side elevation view thereof;
FIG. 5 is a right side elevation view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof; and,
FIG. 8 is a front/right-side/top perspective view thereof showing three water bottles for charging robotic air purifier with water when the top cover is opened.
The features shown in broken lines depict environmental subject matter only and form no part of the claimed design.