I wanted to mount by Bauer Battery Chargers to a French Cleat in my shop.  There is another mount available but you need to get specific screws.  I had difficulty finding them so I designed a simple box/case/mount.  It uses more filament (108g), but I think it would be cheaper than getting the new screws/bolts.

Printed with PLA, 20%infill, supports used to support the window to see the battery light indicator (you may be able to print without them.