I charged mine plugging into a usb wall block for the few days until my Nitecore charger arrived, no problem. I suspect Fuji's 'ambiguous specificity' 🤔 about charging is to protect themselves from liability for damage if someone plugs the camera into a cheap charging block and something bad happens. I think it's wise to charge the battery outside the camera in any case, and it is kind of lame of Fuji not to include a charger (as do Canon, Nikon et al....).